WEBVTT/Users/garcia/Desktop/2023 ESC Seminars/20230531

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Hello, everybody can you all hear me okay
through the Poly?

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Yep.

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OK.

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So welcome to the last 

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ESC seminar of the month of
May. Umm.

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Before we start, I'm just
going to give some brief

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announcements. First,

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remember to take care of
yourself.

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as tomorrow is June 1st.  National
Safety Month. USGS offers

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Employee Assistance

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Program resources and can take a look at

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Link, which I'll post later in
the chat. There is the 2023

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Earthquake Country Alliance Bay Area Spring

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Workshop at the Belmont Sport
Complex on June 15th from 9 to

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noon and our very own Max
Schneider will be giving the

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"Quake Break."

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So the workshop is free, so
please register.

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Building 19 residents
electrical power will be turned

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off on Monday,

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June 5th from 6:00 AM to 6:00
PM, so please make other work

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arrangements on that day.

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GMEG seminar on June 8th 
is gonna be given by Owen

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Callahan on "Fault Studies,
Heterogeneity, Healing, and Hot

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Springs." Also please say
"hi" to the new ESC AO Kristina

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Hearn, who's sitting at Moffett
Field in Trudy's old office.

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And finally. Evan and I officially are no

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longer going to be the seminar
chairs after today. although

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Evan is on vacation, so he
signed off 2 weeks ago.

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So today I'm going to be signing
off and passing the torch on to

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Curtis Baton and Max Schneider.

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So for future seminar 

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recommendations 

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please send them an email and I
will also go on to introduce

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today's seminar speaker, Victor
Tsai from Brown.

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Victor got his Bachelors in
geophysics from Caltech and his

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Masters and PhD, both from
Harvard, where he was advised by

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Jim Rice. From 2009 to 2011 

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he was a Mendenhall

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Post Doc at the USGS Geologic
Hazards Science Center in

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Golden.

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And then returned to Caltech,
where he served as a professor

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in the  lab for Seismo Lab
nearly a decade before joining

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the faculty at Brown.

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Throughout his career, Victor
has applied creative approaches

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on a very large range of topics
in seismology ranging from

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glaciers, ambient noise
tomography, ground motion,

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debris flow and most recently,
earthquake complexity, which is

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apparently the topic of today's
talk.

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He has been recognized by an AGU
KGR Young Scientist Award and SSA

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Charles Rector Award and an NSF
career grant.

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He's also been incredible
mentor, always giving insightful

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advice about both scientific and
professional questions.

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And most recently he is also a new
dad.

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So we really appreciate him
taking time off 

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from what probably amounts to a
second full-time job to give

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the

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talk today.

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So without further ado Victo Tsai.

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Thanks, Shanna for that nice
introduction.

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Indeed, I was just doing baby
care this morning. [laugh

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So umm. Anyway it's great
to be here and I'm glad all of

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you could make it to this talk
before I get started on the

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talk.

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I just wanted to mention my
coauthors, so this has been done

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in collaboration with Greg
Hearth from Brown, Daniel

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Trackman from the University of
Nevada, Reno.

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Yours truly, Shanna. Shanna Chu,
as a postdoc with me who did a

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lot of the work shown
here and then I have a new

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student, Jaeseok Lee, who has been
following up on some of this

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more recently.

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So what am I going to talk about
today?

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Well, today I'm really going to
talk about trying to understand

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earthquake, ground motions and
to some extent this is different

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from just I I'm trying to
determine empirical

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relationships, but really trying
to understand the fundamental

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reasons that ground motions look
the way that they do and also to

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try to be able to predict what
those ground motions are for

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different places.

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So and also before I go on, feel
free to ask questions during the

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talk.

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I assume Shannon can relay those
to me.

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If you have questions or I can
take questions at the end.

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OK, so sorry, did someone say
something?

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No.

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OK, so today I'm going to focus
on trying to understand high

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frequency ground motions and
particularly because these are

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the ground motions that are
often the ones that damage

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buildings and contribute to
fatalities.

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So as probably everyone in the
audience here knows, there are

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multiple causes or multiple
things that affect the high

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frequency ground motions.

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In particular, on there are
paths and site terms that

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contribute to what those ground
motions are, but fundamentally

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the reason that there are high
frequency ground motions in the

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1st place are because of the
earthquake source, and that's

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the part that I'm going to focus
this talk on today.

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And here I just have one example
of an earthquake.

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This is the Loma Prieta
earthquake from 1989 that I'm

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sure a lot of you know very
well.

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And this is a very near field
record.

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So this is from 18 kilometers
away from the away from the

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heat, the center.

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And this is just showing the
acceleration as a function of

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time during the earthquake.

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And as you can see, there's
quite a bit of high frequency

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ground motion and part of the I
what I'm trying to explain today

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is let's say, why is there this
high frequency ground motion and

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how would this high frequency
ground motion be different for

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different earthquakes?

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So is the Loma Prieta earthquake
usual unusual?

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Are there things that we can
predict about its location or

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about the high frequency ground
motions based on its location or

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based on other characteristics?

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So that's what I'm going to
spend most of today talking

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about.

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And this trying to understand
these high frequency ground

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motions is a bit in contrast to
trying to understand low

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frequency ground motions.

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So here I just have an example
of how we actually understand

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extremely well the low frequency
ground motions from earthquakes,

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and this is just one example.

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But this is showing that moment
tensor models generally explain

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low frequency ground motions
incredibly well.

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This is from one of the most
complex earthquakes that

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occurred in the recorded
history, so this is the Sumatra

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2004 Sumatra earthquake.

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But if you only look at the
relatively low frequencies and

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here I forget exactly what the
the frequency band is, but it's

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00:06:57.421 --> 00:07:02.846
it's in the maybe 20 to 32nd and
longer period range here and you

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1417-3
00:07:02.846 --> 00:07:07.696
can see compared the the data in
in black for the vertical

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1417-4
00:07:07.696 --> 00:07:12.299
longitudinal and transverse
components of ground motion

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1417-5
00:07:12.299 --> 00:07:15.093
compared with synthetics in
Gray.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1436-0
00:07:15.443 --> 00:07:20.111
And these synthetics are due to
a relatively simple five point

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1436-1
00:07:20.111 --> 00:07:23.593
source moment tensor model for
the earthquake.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1460-0
00:07:24.013 --> 00:07:28.581
And as I hope you can see, the
synthetics do a remarkable job

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1460-1
00:07:28.581 --> 00:07:32.853
in matching the data at these
relatively low frequencies.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1510-0
00:07:32.913 --> 00:07:37.048
So almost every single wiggle in
the vertical, longitudinal and

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1510-1
00:07:37.048 --> 00:07:41.118
transverse components of ground
motion at these relatively low

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1510-2
00:07:41.118 --> 00:07:44.607
frequencies, even for a
relatively complex earthquake

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1510-3
00:07:44.607 --> 00:07:48.742
like the Sumatra earthquake, we
can predict to a high degree of

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1510-4
00:07:48.742 --> 00:07:49.323
accuracy.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1535-0
00:07:50.063 --> 00:07:53.226
And this is true not just for
this one station, but this is

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1535-1
00:07:53.226 --> 00:07:56.493
true basically for all of the
stations in the global network.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1560-0
00:07:57.483 --> 00:08:01.098
So this is in contrast to what
I'm going to talk about today,

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1560-1
00:08:01.098 --> 00:08:04.013
which is about the high
frequency ground motions.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1562-0
00:08:04.083 --> 00:08:05.053
So unfortunately.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1566-0
00:08:05.783 --> 00:08:06.223
Umm.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1577-0
00:08:06.803 --> 00:08:09.523
High frequency ground motions
are not so easily understood.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1579-0
00:08:10.243 --> 00:08:10.693
Umm.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1628-0
00:08:10.903 --> 00:08:14.940
Meaning that for example, the
ground motion models that people

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1628-1
00:08:14.940 --> 00:08:18.976
use to try to predict what the
ground motions are at different

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1628-2
00:08:18.976 --> 00:08:22.115
sites that we have generally
have a very limited

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1628-3
00:08:22.115 --> 00:08:26.151
understanding of what causes the
interevent variability that's

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1628-4
00:08:26.151 --> 00:08:28.713
observed from earthquake to
earthquake.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1650-0
00:08:29.043 --> 00:08:33.523
So in the typical ground motion
models, there are various terms

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1650-1
00:08:33.523 --> 00:08:35.553
that have a source component.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1665-0
00:08:35.563 --> 00:08:39.119
For example, the faulting style
and how that affects ground

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1665-1
00:08:39.119 --> 00:08:39.593
motions.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1710-0
00:08:40.373 --> 00:08:44.137
But generally these empirical
correlations are not very well

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1710-1
00:08:44.137 --> 00:08:47.962
understood in terms of why they
exist in the 1st place and if

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1710-2
00:08:47.962 --> 00:08:51.602
they can do a good job and
explaining why different events

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1710-3
00:08:51.602 --> 00:08:55.673
have different amounts of ground
motions at the high frequencies.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1723-0
00:08:57.133 --> 00:09:00.053
So this is the problem that I'm
going to talk about today.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1728-0
00:09:00.663 --> 00:09:01.133
Umm.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1808-0
00:09:01.423 --> 00:09:06.676
If we can try to explain what
causes these high frequency

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1808-1
00:09:06.676 --> 00:09:12.200
ground motions and I'm going to
spend pretty much the entire

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1808-2
00:09:12.200 --> 00:09:17.995
talk showing or sorry, OK before
I go to that, I it in addition

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1808-3
00:09:17.995 --> 00:09:23.610
to the ground motion models not
doing a not understanding the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1808-4
00:09:23.610 --> 00:09:29.224
cause of these high frequency
ground motions, umm simulations

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1808-5
00:09:29.224 --> 00:09:34.567
also do not do a great job in
explaining what those ground

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1808-6
00:09:34.567 --> 00:09:35.653
motions are.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1844-0
00:09:35.923 --> 00:09:39.827
And so I'm gonna show just one
example of what those what those

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1844-1
00:09:39.827 --> 00:09:43.182
simulations look like for the
sort of state of the art

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1844-2
00:09:43.182 --> 00:09:46.293
simulations that are people have
been doing today.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1858-0
00:09:46.943 --> 00:09:50.433
This is just one example from
Eric Dunham's group up at

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1858-1
00:09:50.433 --> 00:09:50.993
Stanford.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1913-0
00:09:51.383 --> 00:09:55.948
But this is one example showing
that if you put in a semi

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1913-1
00:09:55.948 --> 00:10:00.591
realistic kind of rough adult
and you do a dynamic rupture

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1913-2
00:10:00.591 --> 00:10:05.627
simulations on this rough fault,
then you can get what appeared

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1913-3
00:10:05.627 --> 00:10:10.034
to be quite complex ground
motions with this wave field

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1913-4
00:10:10.034 --> 00:10:13.103
being depicted in this plot over
here.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/1920-0
00:10:13.203 --> 00:10:14.253
I'm with the.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2004-0
00:10:14.643 --> 00:10:19.619
You can see the the S wave being
radiated outward in this reddish

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2004-1
00:10:19.619 --> 00:10:23.991
color, and you can see the
complexity in terms of how the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2004-2
00:10:23.991 --> 00:10:28.589
these colors sort of oscillate
in space, and so these models

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2004-3
00:10:28.589 --> 00:10:32.811
have been getting better and
better, and they're at the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2004-4
00:10:32.811 --> 00:10:37.032
bottom of my slide is just a
list of some of the recent

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2004-5
00:10:37.032 --> 00:10:41.857
simulations that try to get into
more and more realism in terms

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2004-6
00:10:41.857 --> 00:10:45.173
of how to think about these
ground motions.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2019-0
00:10:45.643 --> 00:10:49.177
But one of the challenges is
that they don't actually predict

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2019-1
00:10:49.177 --> 00:10:50.773
the observed ground motions.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2046-0
00:10:50.783 --> 00:10:55.028
All that well, this is a plot on
the lower left, lower right here

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2046-1
00:10:55.028 --> 00:10:58.630
of the acceleration spectral
amplitude as a function of

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2046-2
00:10:58.630 --> 00:10:59.273
frequency.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2098-0
00:11:00.073 --> 00:11:04.171
So taking the taking this
snapshot of the ground motions

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2098-1
00:11:04.171 --> 00:11:08.412
and converting it into the
frequency domain and as you can

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2098-2
00:11:08.412 --> 00:11:13.012
see here, there's differences in
how much of the high frequency

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2098-3
00:11:13.012 --> 00:11:16.822
ground motions are excited
depending on what kind of

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2098-4
00:11:16.822 --> 00:11:18.403
roughness they put in.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2182-0
00:11:18.413 --> 00:11:22.654
So if they put in a flat non
rough fault, they have less high

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2182-1
00:11:22.654 --> 00:11:26.964
frequency ground motions and if
they put in a realistic amount

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2182-2
00:11:26.964 --> 00:11:31.000
of roughness this sort of 10 to
the minus three roughness,

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2182-3
00:11:31.000 --> 00:11:35.172
meaning that the amplitude of
the roughness is approximately

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2182-4
00:11:35.172 --> 00:11:39.481
10 to the minus three times the
length scale or the wavelength

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2182-5
00:11:39.481 --> 00:11:43.654
of that roughness, then you get
this sort of prediction here

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2182-6
00:11:43.654 --> 00:11:47.895
where this reddish color shows
the predictions for that 10 to

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2182-7
00:11:47.895 --> 00:11:49.673
the minus three roughness.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2242-0
00:11:50.303 --> 00:11:54.606
Unfortunately, what's actually
observed, and I'm not going to

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2242-1
00:11:54.606 --> 00:11:58.771
show why this is the case, but
if you take that Loma Prieta

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2242-2
00:11:58.771 --> 00:12:02.588
example, for example, you find
that at the at the high

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2242-3
00:12:02.588 --> 00:12:06.891
frequencies, if you're in the
near field, I'm where the waves

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2242-4
00:12:06.891 --> 00:12:08.903
have not yet attenuated away.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2257-0
00:12:09.033 --> 00:12:12.350
What's generally observed is
that the acceleration spectrum

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2257-1
00:12:12.350 --> 00:12:15.003
is relatively flat across this
frequency range.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2292-0
00:12:15.553 --> 00:12:19.995
So what's observed is that the,
umm, that there's not much decay

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2292-1
00:12:19.995 --> 00:12:23.753
in terms of the energy from low
frequencies up to high

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2292-2
00:12:23.753 --> 00:12:26.623
frequencies through this
frequency range.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2316-0
00:12:27.073 --> 00:12:31.185
But what these models predict is
still with realistic roughness,

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2316-1
00:12:31.185 --> 00:12:35.233
that there's a significant decay
of energy at high frequencies.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2381-0
00:12:36.593 --> 00:12:41.930
And so today I'm going to try to
talk about why I'm whether we

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2327-0
00:12:36.873 --> 00:12:37.133
So.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2381-1
00:12:41.930 --> 00:12:47.437
can understand what causes that
additional high frequency ground

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2381-2
00:12:47.437 --> 00:12:52.265
motion that is not being
captured, for example, in these

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2381-3
00:12:52.265 --> 00:12:57.856
state of the art simulations and
what I'm going to focus on today

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2381-4
00:12:57.856 --> 00:13:03.193
is that the potential cause that
complex geometries within the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2381-5
00:13:03.193 --> 00:13:04.463
fault zone can.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2447-0
00:13:05.863 --> 00:13:09.419
How that can result in
additional components to the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2447-1
00:13:09.419 --> 00:13:13.044
ground motions and the
motivation for this is really

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2447-2
00:13:13.044 --> 00:13:17.078
that, uh, basically all the
field observations that people

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2447-3
00:13:17.078 --> 00:13:21.318
have made from around the world
in different fault zones have

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2447-4
00:13:21.318 --> 00:13:25.285
shown that fault zones are
indeed quite complex and these

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2447-5
00:13:25.285 --> 00:13:28.293
are just a few examples of that
complexity.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2546-0
00:13:28.703 --> 00:13:33.069
So here on the upper left I have
an example at the sort of 500

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2546-1
00:13:33.069 --> 00:13:37.295
meter or kilometer scale where
you can see quite significant

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2546-2
00:13:37.295 --> 00:13:41.522
amount of fault zone complexity
and one of the things that I

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2546-3
00:13:41.522 --> 00:13:45.333
wanted to point out in this
figure is that these fault

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2546-4
00:13:45.333 --> 00:13:49.421
zones, I'm not only is there
complexity along single fault

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2546-5
00:13:49.421 --> 00:13:53.717
strands, but there is a lot of
additional complexity in terms

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2546-6
00:13:53.717 --> 00:13:57.459
of these additional fault
strands that are in related

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2546-7
00:13:57.459 --> 00:14:01.824
areas, let's say within the zone
that people might think of as

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2546-8
00:14:01.824 --> 00:14:02.863
the fault zone.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2577-0
00:14:03.093 --> 00:14:07.625
So at the sort of kilometer
scale or 500 meter scale, there

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2577-1
00:14:07.625 --> 00:14:11.778
are all of these different
structures that potentially

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2577-2
00:14:11.778 --> 00:14:14.043
interact during an earthquake.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2590-0
00:14:14.693 --> 00:14:18.023
And this is true at the a
smaller scale as well.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2594-0
00:14:18.413 --> 00:14:19.593
And so they're not.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2617-0
00:14:19.603 --> 00:14:22.375
Maybe not as many good
observations that these smaller

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2617-1
00:14:22.375 --> 00:14:24.743
scales, but there are these at
least a couple.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2635-0
00:14:25.093 --> 00:14:28.545
These are a couple of
observations from Mark Swanson

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2635-1
00:14:28.545 --> 00:14:30.433
for an exhume fault in Maine.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2693-0
00:14:30.443 --> 00:14:34.768
Actually the the fault that was
on my title slide, which since

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2693-1
00:14:34.768 --> 00:14:38.612
the time that it was seismogenic
it has had very little

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2693-2
00:14:38.612 --> 00:14:42.730
deformation and so one can see
almost perfectly intact what

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2693-3
00:14:42.730 --> 00:14:46.986
these fault structures looked
like when it was seismogenic at

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2693-4
00:14:46.986 --> 00:14:48.633
7 or 8 kilometers depth.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2799-0
00:14:49.133 --> 00:14:53.389
And what you can see here is
again at this relatively small

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2799-1
00:14:53.389 --> 00:14:57.431
scale now at a either 2 meter
scale or at the four meter

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2799-2
00:14:57.431 --> 00:15:01.899
scale, you can again see this
significant amount of fault zone

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2799-3
00:15:01.899 --> 00:15:06.012
complexity that really you can
see all of these different

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2799-4
00:15:06.012 --> 00:15:10.125
structures and you can even
trace the amount of slip that

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2799-5
00:15:10.125 --> 00:15:14.451
was on each of these different
structures at the meter scale

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2799-6
00:15:14.451 --> 00:15:18.919
and yeah, so basically all of
the different field observations

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2799-7
00:15:18.919 --> 00:15:23.032
that we've had show that
basically everywhere we've gone,

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2799-8
00:15:23.032 --> 00:15:26.932
there's some amount of
geometrical complexity of these

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2799-9
00:15:26.932 --> 00:15:27.783
fault zones.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2816-0
00:15:28.773 --> 00:15:32.957
And in fact, this is even true
of fault zones that are

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2816-1
00:15:32.957 --> 00:15:35.543
notoriously thought of as
simple.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2830-0
00:15:36.133 --> 00:15:39.103
So this is one example from the
Punch Bowl fault.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2878-0
00:15:39.143 --> 00:15:43.843
The Punch Bowl fault is maybe
the fault that people think of

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2878-1
00:15:43.843 --> 00:15:47.618
as being the most
stereotypically simple, with a

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2878-2
00:15:47.618 --> 00:15:52.241
very clean knife edge, principal
slip surface, which people

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2878-3
00:15:52.241 --> 00:15:56.093
interpret that a lot of the slip
has occurred on.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2901-0
00:15:56.443 --> 00:16:00.791
But even a fault as simple as
the Punch Bowl fault has quite

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2901-1
00:16:00.791 --> 00:16:04.853
significant geometrical
complexity at a range of scales.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2951-0
00:16:05.003 --> 00:16:09.157
So both at the five kilometer
scale here where you can see a

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2951-1
00:16:09.157 --> 00:16:13.242
lot of different structures
where slip could be partitioned

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2951-2
00:16:13.242 --> 00:16:17.191
between let's say and also at
this relatively small scale

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2951-3
00:16:17.191 --> 00:16:21.003
where you see the principal slip
surface in the middle.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2988-0
00:16:21.543 --> 00:16:25.266
But at the centimeter scale, you
can also see quite a lot of

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2988-1
00:16:25.266 --> 00:16:28.806
complexity of what the fault
zone actually looks like and

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/2988-2
00:16:28.806 --> 00:16:32.223
potentially where slip might
have occurred in the past.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3061-0
00:16:34.153 --> 00:16:39.654
Even for these relatively simple
faults so with that motivation.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3061-1
00:16:39.654 --> 00:16:44.900
I'm going to spend really the
rest of this talk talking about

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3061-2
00:16:44.900 --> 00:16:50.231
the potential role that these
let's say this. This geometrical

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3061-3
00:16:50.231 --> 00:16:55.139
complexity of fault zones could
have on earthquake ground

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3061-4
00:16:55.139 --> 00:17:00.470
motions and I'm going to take
now a step back and really think

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3061-5
00:17:00.470 --> 00:17:04.023
about this thought experiment
about well?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3071-0
00:17:04.033 --> 00:17:09.135
What happens when an earthquake
nucleates within a nominally

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3071-1
00:17:09.135 --> 00:17:10.723
complex fault zone?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3089-0
00:17:11.393 --> 00:17:14.701
What do we expect should happen,
and are there predictions that

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3089-1
00:17:14.701 --> 00:17:16.303
we can make about what happens?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3111-0
00:17:16.513 --> 00:17:20.535
So in this thought experiment
I'm I'm I'm going to envision

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3111-1
00:17:20.535 --> 00:17:22.813
there being a complex fault
zone.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3123-0
00:17:23.153 --> 00:17:27.432
I'm and we're just gonna assume
that this complex fault zone

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3123-1
00:17:27.432 --> 00:17:27.923
exists.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3148-0
00:17:28.293 --> 00:17:32.592
So for example, there are all of
these possible black lines which

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3148-1
00:17:32.592 --> 00:17:35.783
are fault structures within a
larger fault zone.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3181-0
00:17:36.163 --> 00:17:41.499
And let's say that an earthquake
starts along what we call this

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3181-1
00:17:41.499 --> 00:17:46.502
principle slip surface in green
and an earthquake starts to

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3181-2
00:17:46.502 --> 00:17:50.003
propagate on this principle slip
surface.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3206-0
00:17:51.073 --> 00:17:54.995
But the question that I'm asking
here and that hopefully I can

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3206-1
00:17:54.995 --> 00:17:58.543
lead you through today, is well,
what what happens next?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3235-0
00:17:58.933 --> 00:18:04.001
What happens when this slip
tries to continue to propagate

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3235-1
00:18:04.001 --> 00:18:08.896
as an earthquake, and what
happens explicitly due to the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3235-2
00:18:08.896 --> 00:18:12.503
geometrical complexity of the
fault zone?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3287-0
00:18:13.273 --> 00:18:18.240
Well, perhaps the thing that I
want you to notice is that just

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3287-1
00:18:18.240 --> 00:18:22.654
like people study step overs and
compressional dens and

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3287-2
00:18:22.654 --> 00:18:27.147
extensional dens at a larger
scale within the fault zone

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3287-3
00:18:27.147 --> 00:18:31.404
scale, we also see that there
are these compressional

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3287-4
00:18:31.404 --> 00:18:32.113
segments.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3295-0
00:18:32.123 --> 00:18:34.953
For example, there's one of them
right here.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3305-0
00:18:35.543 --> 00:18:37.233
You might think of this as a
compressional.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3310-0
00:18:37.243 --> 00:18:37.813
Step over.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3371-0
00:18:37.823 --> 00:18:42.463
If it were at a larger scale,
and there's extensional step

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3371-1
00:18:42.463 --> 00:18:47.260
overs at in other places, like
over there, and so one of the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3371-2
00:18:47.260 --> 00:18:51.979
questions then is, well, if a
slip really tries to tries to

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3371-3
00:18:51.979 --> 00:18:56.304
occur at a scale that's larger
than the scale of these

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3371-4
00:18:56.304 --> 00:19:00.943
structures, then something has
to happen at each of these.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3377-0
00:19:01.233 --> 00:19:02.443
Step over points.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3399-0
00:19:02.893 --> 00:19:06.458
In particular, if you think
about what happens at this

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3399-1
00:19:06.458 --> 00:19:09.503
compressional compressional bend
in the fault.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3449-0
00:19:10.073 --> 00:19:14.070
Basically the stresses get
loaded to a very high amount and

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3449-1
00:19:14.070 --> 00:19:18.067
there's a question then about
what happens next with one of

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3449-2
00:19:18.067 --> 00:19:22.330
the options being that slip gets
transferred until one of those

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3449-3
00:19:22.330 --> 00:19:25.593
subsidiary faults that is
assumed to exist here.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3462-0
00:19:26.123 --> 00:19:29.363
So if I were to draw what might
happen?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3468-0
00:19:29.803 --> 00:19:31.913
I'm at one of these.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3471-0
00:19:30.643 --> 00:19:30.803
Yes.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3475-0
00:19:32.143 --> 00:19:33.273
Step over points.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3487-0
00:19:33.683 --> 00:19:37.713
One of the options when slip
tries to occur at this.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3525-0
00:19:37.923 --> 00:19:42.591
At this point is that you could
have slip transferred from what

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3525-1
00:19:42.591 --> 00:19:46.822
was the green fault to this blue
fault, or you could have

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3514-0
00:19:46.063 --> 00:19:46.263
Easy.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3525-2
00:19:46.822 --> 00:19:50.979
transferred from this green
fault to this red fault over

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3525-3
00:19:50.979 --> 00:19:51.343
here.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3587-0
00:19:52.643 --> 00:19:57.546
And one way of thinking about
what happens there is that as

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3587-1
00:19:57.546 --> 00:20:02.285
slip occurs, there is this
geometrical incompatibility at

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3587-2
00:20:02.285 --> 00:20:07.025
each of these points, which
results in elastic loading of

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3587-3
00:20:07.025 --> 00:20:11.601
that point, and if the slip
transfers on to a different

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3587-4
00:20:11.601 --> 00:20:16.422
strand, then there is unloading
of stress at each of those

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3587-5
00:20:16.422 --> 00:20:16.993
points.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3604-0
00:20:17.803 --> 00:20:21.113
So this is a sort of qualitative
way of thinking about it.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3668-0
00:20:21.183 --> 00:20:25.152
But I think it's a very useful
one because one can now think

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3668-1
00:20:25.152 --> 00:20:28.926
about it in terms of the
structures in between the faults

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3668-2
00:20:28.926 --> 00:20:32.960
and what happens if you, for
example, consider this structure

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3668-3
00:20:32.960 --> 00:20:37.124
over in the upper left is that
it was originally moving towards

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3668-4
00:20:37.124 --> 00:20:41.223
the right because of this right
lateral shear that was imposed

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3668-5
00:20:41.223 --> 00:20:41.613
on it.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3702-0
00:20:42.003 --> 00:20:46.043
But after the slip transfers to
the to the blue fault, then that

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3702-1
00:20:46.043 --> 00:20:49.958
structure would have would now
be moving to the left or mostly

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3701-0
00:20:47.853 --> 00:20:48.453
So inside.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3702-2
00:20:49.958 --> 00:20:50.703
to the left.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3706-0
00:20:50.803 --> 00:20:51.483
Not exactly.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3708-0
00:20:51.493 --> 00:20:51.853
To the left.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3712-0
00:20:52.543 --> 00:20:52.973
Umm.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3724-0
00:20:53.083 --> 00:20:56.413
So if you think about then what
happens to that structure?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3742-0
00:20:56.703 --> 00:20:59.661
It was originally moving to the
right, and now it's moving

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3742-1
00:20:59.661 --> 00:21:00.613
mostly to the left.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3785-0
00:21:01.003 --> 00:21:05.845
And what really occurred during
that transition is that there

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3785-1
00:21:05.845 --> 00:21:10.608
was a change in momentum of this
little structure within the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3785-2
00:21:10.608 --> 00:21:15.605
fault zone that transferred its
momentum from from going to the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3785-3
00:21:15.605 --> 00:21:17.713
right to going to the left.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3803-0
00:21:18.303 --> 00:21:21.952
And so that is the type of
behavior that I'm going to talk

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3803-1
00:21:21.952 --> 00:21:22.693
about today.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3834-0
00:21:23.673 --> 00:21:27.753
And the way that I'm going to
think about each of these slip

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3834-1
00:21:27.753 --> 00:21:31.633
transfer events is really in
terms of these structures in

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3834-2
00:21:31.633 --> 00:21:32.903
between the faults.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3885-0
00:21:33.013 --> 00:21:36.802
And it's a different way than
most people usually think about

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3885-1
00:21:36.802 --> 00:21:40.467
it, but if you, if you think
about it now in terms of those

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3885-2
00:21:40.467 --> 00:21:44.072
structures that change in
momentum from going to the right

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3885-3
00:21:44.072 --> 00:21:47.677
to going to the left can be
really thought of as an impact

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3885-4
00:21:47.677 --> 00:21:48.043
event.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3917-0
00:21:48.633 --> 00:21:52.993
Even though this structure is
highly confined within the fault

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3917-1
00:21:52.993 --> 00:21:57.075
zone, umm, and it's not like a
traditional impact like you

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3917-2
00:21:57.075 --> 00:22:00.673
might think of as a ball hitting
the table surface.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3964-0
00:22:01.443 --> 00:22:05.546
So it's not unconfined like
that, but it has some of the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3964-1
00:22:05.546 --> 00:22:09.792
same physics as an unconfined
impact in the sense that the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3964-2
00:22:09.792 --> 00:22:14.326
momentum change is important,
and that in this momentum change

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3964-3
00:22:14.326 --> 00:22:18.860
the most important physics is
actually the elastic compression

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/3964-4
00:22:18.860 --> 00:22:19.723
and elastic.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4042-0
00:22:20.013 --> 00:22:24.434
Umm, the elastic loading and
unloading that occurs during

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4042-1
00:22:24.434 --> 00:22:29.312
that change in momentum and one
of the interesting consequences

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4042-2
00:22:29.312 --> 00:22:34.114
of thinking about it in this way
is that actually to 1st order

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4042-3
00:22:34.114 --> 00:22:38.383
the prediction of this kind of
impact model is that the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4042-4
00:22:38.383 --> 00:22:43.413
momentum transfer that occurs or
in other words, the contribution

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4042-5
00:22:43.413 --> 00:22:47.834
to ground motion that this
additional slip transfer event

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4042-6
00:22:47.834 --> 00:22:51.873
caused is actually somewhat
independent of friction.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4048-0
00:22:52.883 --> 00:22:55.793
And that's a interesting
consequence.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4072-0
00:22:56.743 --> 00:23:01.216
But it's really because friction
only comes into second order in

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4072-1
00:23:01.216 --> 00:23:04.793
thinking about what is happening
to that structure.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4097-0
00:23:05.343 --> 00:23:08.051
It's true that if you were to
include friction, you would get

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4097-1
00:23:08.051 --> 00:23:09.273
a slightly different answer.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4197-0
00:23:09.683 --> 00:23:14.399
But if friction is relatively
low in the less than one type of

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4197-1
00:23:14.399 --> 00:23:18.891
number, then then the typically
the contribution due to the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4197-2
00:23:18.891 --> 00:23:23.607
friction is relatively small to
that and and the other thing I

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4197-3
00:23:23.607 --> 00:23:28.173
wanted to focus on was that in
terms of thinking about these

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4197-4
00:23:28.173 --> 00:23:32.964
impact events, the time scale of
these impact events can really

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4197-5
00:23:32.964 --> 00:23:37.680
be thought of just like the time
scale of a ball bouncing on a

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4197-6
00:23:37.680 --> 00:23:42.171
table in terms of the amount of
elastic compression and the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4197-7
00:23:42.171 --> 00:23:46.962
amount of umm, elastic loading
and unloading that has to happen

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4197-8
00:23:46.962 --> 00:23:48.983
during one of these events.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4200-0
00:23:49.593 --> 00:23:52.223
I'm and what?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4208-0
00:23:52.433 --> 00:23:53.983
There's a question, then, of
what?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4218-0
00:23:53.993 --> 00:23:57.243
What causes that time scale, or
the spectral contribution?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4240-0
00:23:57.633 --> 00:24:03.327
And it's really the size and the
geometry of these objects that

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4240-1
00:24:03.327 --> 00:24:05.283
causes the time scale.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4253-0
00:24:05.533 --> 00:24:10.930
Or in other words, causes the
frequency contribution to each

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4253-1
00:24:10.930 --> 00:24:13.053
of these impact defense.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4312-0
00:24:13.553 --> 00:24:17.330
So in other words, if you know
something about the size and the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4312-1
00:24:17.330 --> 00:24:20.871
structures of each of these
fault zone pieces, then you can

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4312-2
00:24:20.871 --> 00:24:24.471
make a prediction in terms of
what is the time scale or what

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4312-3
00:24:24.471 --> 00:24:27.776
is the frequency content that
you would expect of these

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4312-4
00:24:27.776 --> 00:24:30.313
additional contributions to
ground motion.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4328-0
00:24:30.663 --> 00:24:34.589
Beyond having this overall,
let's say write lateral share

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4328-1
00:24:34.589 --> 00:24:36.483
superimposed on top of that?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4356-0
00:24:38.003 --> 00:24:42.330
Umm, something that I'm not
going to really have time to get

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4356-1
00:24:42.330 --> 00:24:46.231
into is that you can make a
prediction for the for the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4356-2
00:24:46.231 --> 00:24:47.223
Spectra given.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4383-0
00:24:47.993 --> 00:24:52.208
Uh known statistics of the size
and the geometry of these of

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4383-1
00:24:52.208 --> 00:24:55.593
these structures, or of the
faults between them?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4387-0
00:24:56.363 --> 00:24:56.793
Umm.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4447-0
00:24:57.123 --> 00:25:01.573
And I'm not going to get into
exactly how how we do that, but

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4447-1
00:25:01.573 --> 00:25:06.023
the nice thing is that we don't
need to know everything about

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4447-2
00:25:06.023 --> 00:25:10.544
all of these structures as long
as we know something about the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4447-3
00:25:10.544 --> 00:25:15.137
statistics of them, then we can
make some predictions about the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4447-4
00:25:15.137 --> 00:25:19.443
expected time scales or the
expected frequency content, OK?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4449-0
00:25:19.633 --> 00:25:20.623
And I'm.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4507-0
00:25:20.633 --> 00:25:24.600
I'm just going to spend 1 slide
talking about some of the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4507-1
00:25:24.600 --> 00:25:28.908
details of the model because I
think it's important to to show

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4507-2
00:25:28.908 --> 00:25:33.148
really how relatively simple on
this model is because it's an

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4507-3
00:25:33.148 --> 00:25:37.046
elastic impact model where
elasticity is really the only

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4507-4
00:25:37.046 --> 00:25:40.123
ingredient that is important to
first order.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4548-0
00:25:40.873 --> 00:25:45.652
Then we have a relatively simple
theory for understanding how

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4548-1
00:25:45.652 --> 00:25:50.199
these impacts cause ground
motions, and in particular with

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4548-2
00:25:50.199 --> 00:25:54.977
a focus on the time scale of the
additional forcings that are

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4548-3
00:25:54.977 --> 00:25:55.593
created.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4564-0
00:25:56.313 --> 00:25:59.951
And this theory goes back to
Hertz from more than 100 years

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4564-1
00:25:59.951 --> 00:26:00.193
ago.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4567-0
00:26:00.753 --> 00:26:01.193
Umm.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4621-0
00:26:01.673 --> 00:26:06.051
As a side note, Hertz was
actually interested in trying to

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4621-1
00:26:06.051 --> 00:26:10.502
understand the elastic loading
of glass plates as they were

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4621-2
00:26:10.502 --> 00:26:15.102
compressed together, but the
same theory can explain the time

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4621-3
00:26:15.102 --> 00:26:18.143
scales of a ball bouncing on on
a table.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4697-0
00:26:18.473 --> 00:26:22.027
For example, trying to
understand how long is the ball

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4697-1
00:26:22.027 --> 00:26:25.838
actually in contact with the
surface of the table and that

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4697-2
00:26:25.838 --> 00:26:29.456
time scale is very much
important to understanding what

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4697-3
00:26:29.456 --> 00:26:33.655
time scale of a ground motion is
produced from that impact event

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4697-4
00:26:33.655 --> 00:26:37.725
and in the same way we can think
about the time scale of these

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4697-5
00:26:37.725 --> 00:26:41.730
structures and how they interact
with each other in the fault

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4697-6
00:26:41.730 --> 00:26:42.053
zone.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4729-0
00:26:42.673 --> 00:26:45.633
And I'm not going to get really
into the details here, but we

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4729-1
00:26:45.633 --> 00:26:48.640
have a prediction, a very simple
prediction, that goes back to

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4729-2
00:26:48.640 --> 00:26:50.453
Hertzian theory about the time
scale.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4752-0
00:26:51.083 --> 00:26:54.576
This is the contact time scale
and how the contact time skills

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4752-1
00:26:54.576 --> 00:26:57.513
related to different properties
of those structures.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4765-0
00:26:58.023 --> 00:26:59.743
So it's related to the mass of
each of the.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4823-0
00:27:00.753 --> 00:27:05.789
So the particles related to the
radius of curvature related to

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4823-1
00:27:05.789 --> 00:27:10.744
the elastic modulus and related
to the velocity of impact and

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4823-2
00:27:10.744 --> 00:27:16.020
you can translate that into this
other equation where you can see

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4823-3
00:27:16.020 --> 00:27:21.135
that there's actually only two
parameters here that are two are

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4823-4
00:27:21.135 --> 00:27:22.893
relatively high power.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4841-0
00:27:23.453 --> 00:27:27.226
First of all, there's this
linear relationship between the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4841-1
00:27:27.226 --> 00:27:30.103
time scale and the size of these
structures.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4886-0
00:27:30.113 --> 00:27:34.096
Where R is the, let's say
average size of one of these

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4886-1
00:27:34.096 --> 00:27:38.585
structures, and then the only
other parameter here that has a

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4886-2
00:27:38.585 --> 00:27:43.147
significant dependence is this
on PC parameter which has to do

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4886-3
00:27:43.147 --> 00:27:45.753
with the geometry of the
structure.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4916-0
00:27:46.383 --> 00:27:52.110
So this has to do with the
aspect ratio of the structure

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4916-1
00:27:52.110 --> 00:27:57.333
and this the time scale goes as
C to the 4th power.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4987-0
00:27:57.343 --> 00:28:01.082
So a relatively high power,
whereas all of the other

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4987-1
00:28:01.082 --> 00:28:05.526
parameters on our scaling with a
relatively low power and what

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4987-2
00:28:05.526 --> 00:28:10.111
that implies is really that it's
really this geometric parameter

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4987-3
00:28:10.111 --> 00:28:14.696
and the size parameter that have
the biggest effect, the biggest

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4987-4
00:28:14.696 --> 00:28:18.928
predicted effect on what the
time scale of these impacts is

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/4987-5
00:28:18.928 --> 00:28:22.313
and hence what the frequency
content should be.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5015-0
00:28:23.363 --> 00:28:27.060
There are complexities due to
lots of different possible

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5015-1
00:28:27.060 --> 00:28:31.017
geometries that I'm not going to
get into, but this has some

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5015-2
00:28:31.017 --> 00:28:32.573
interesting conclusions.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5037-0
00:28:32.583 --> 00:28:36.612
If you if you believe this type
of model might explain some of

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5037-1
00:28:36.612 --> 00:28:40.193
the ground motions and I'll just
highlight two of them.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5096-0
00:28:41.113 --> 00:28:45.556
Which is that if you believe
that this is what is causing

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5096-1
00:28:45.556 --> 00:28:49.999
additional contributions to
ground motion beyond just the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5096-2
00:28:49.999 --> 00:28:54.901
large scale planar shear, then
there's this component of ground

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5096-3
00:28:54.901 --> 00:28:59.727
motions that is caused by the
geometry of these structures and

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5096-4
00:28:59.727 --> 00:29:03.863
really not caused by friction,
at least to 1st order.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5175-0
00:29:04.323 --> 00:29:08.284
Umm, there's a small frictional
component, but at least it's not

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5175-1
00:29:08.284 --> 00:29:12.000
important if you make a first
order prediction and so that's

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5175-2
00:29:12.000 --> 00:29:15.473
very much different from how
most people think about the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5175-3
00:29:15.473 --> 00:29:18.946
contributions to high frequency
ground motions where the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5175-4
00:29:18.946 --> 00:29:22.724
standard model would be saying
that, umm, there's a component

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5175-5
00:29:22.724 --> 00:29:26.684
of high frequency ground motions
that is due to very small scale

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5175-6
00:29:26.684 --> 00:29:29.913
slip on a planar surface or a
nearly planar surface.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5193-0
00:29:30.063 --> 00:29:33.821
Maybe with a little bit of
roughness and this model is

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5193-1
00:29:33.821 --> 00:29:36.963
claiming something quite
different from that.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5217-0
00:29:37.083 --> 00:29:41.882
That is really caused by the
geometry and the the size and

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5217-1
00:29:41.882 --> 00:29:45.705
the and the geometric
characteristics of those

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5217-2
00:29:45.705 --> 00:29:47.413
different structures.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5272-0
00:29:48.403 --> 00:29:52.503
The second implication that I
wanted to highlight today is

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5272-1
00:29:52.503 --> 00:29:56.742
that on if you were to make
stress drop inferences from high

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5272-2
00:29:56.742 --> 00:30:00.633
frequency corner corner
frequency measurements, umm and

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5272-3
00:30:00.633 --> 00:30:04.524
there is this additional
contribution to ground motions

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5272-4
00:30:04.524 --> 00:30:07.303
that's caused by these elastic
impacts.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5313-0
00:30:07.773 --> 00:30:11.976
Well then that means that the
model you should be using to

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5313-1
00:30:11.976 --> 00:30:15.680
interpret those corner
frequencies would need to be

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5313-2
00:30:15.680 --> 00:30:19.597
modified and would need to be
modified to include this

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5313-3
00:30:19.597 --> 00:30:22.303
component that's related to
geometry.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5351-0
00:30:22.633 --> 00:30:26.846
And so there's this implication
that potentially these

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5351-1
00:30:26.846 --> 00:30:31.213
seismological inferences of
stress drop may be biased by

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5351-2
00:30:31.213 --> 00:30:35.579
these contributions to high
frequency ground motion from

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5351-3
00:30:35.579 --> 00:30:37.953
these geometrical complexities.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5395-0
00:30:39.063 --> 00:30:39.503
OK.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5398-0
00:30:39.513 --> 00:30:43.620
So that's all I think I'm going
to say about the sort of

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5398-1
00:30:43.620 --> 00:30:47.871
predictions that we make from
from this sort of geometric,

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5398-2
00:30:47.871 --> 00:30:52.050
this fault fault, network
complexity model, and I'm going

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5398-3
00:30:52.050 --> 00:30:54.283
to spend the rest of this talk.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5446-0
00:30:55.483 --> 00:30:59.105
Talking about some of the
observational some of the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5446-1
00:30:59.105 --> 00:31:02.936
predicted observational
differences and how we can try

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5446-2
00:31:02.936 --> 00:31:07.185
to go about testing whether this
elastic impact model really

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5446-3
00:31:07.185 --> 00:31:11.363
let's say can explain some of
the observations that we see.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5477-0
00:31:12.703 --> 00:31:17.017
I think I'm only gonna have time
today to talk about this first

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5477-1
00:31:17.017 --> 00:31:21.196
one, but there are a series of
different types of predictions

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5477-2
00:31:21.196 --> 00:31:22.813
we make from this model.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5498-0
00:31:22.823 --> 00:31:26.418
So we make predictions in terms
of differences and what causes

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5498-1
00:31:26.418 --> 00:31:29.213
the variability of high
frequency ground motion.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5540-0
00:31:29.223 --> 00:31:32.508
That's stuff that I already
talked about, something that I

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5540-1
00:31:32.508 --> 00:31:36.182
didn't really talk about much is
that we also predict there to be

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5540-2
00:31:36.182 --> 00:31:39.021
differences in the high
frequency focal mechanisms

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5540-3
00:31:39.021 --> 00:31:41.693
compared to what standard models
would predict.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5557-0
00:31:42.333 --> 00:31:47.726
And we also predict differences
in the the ratios of PTOS wave

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5557-1
00:31:47.726 --> 00:31:48.753
energies at.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5591-0
00:31:49.833 --> 00:31:52.867
Especially at high frequencies,
but I'm really just gonna focus

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5591-1
00:31:52.867 --> 00:31:55.616
on this first one because I
think that's all I'm going to

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5591-2
00:31:55.616 --> 00:31:56.753
have time to talk about.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5627-0
00:31:57.903 --> 00:32:02.466
And as I mentioned previously,
these sort of standard rough

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5627-1
00:32:02.466 --> 00:32:06.952
fault frictional models predict
that and heterogeneity and

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5627-2
00:32:06.952 --> 00:32:11.439
stress drop, heterogeneous slip
and to some extent the off

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5627-3
00:32:11.439 --> 00:32:13.263
fault, umm viscoplastic.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5633-0
00:32:14.693 --> 00:32:15.483
Parameters.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5710-0
00:32:15.693 --> 00:32:19.955
So in terms of viscosity or some
of these other parameters that

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5710-1
00:32:19.955 --> 00:32:23.950
might apply off of the fault,
that's what these rough fault

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5710-2
00:32:23.950 --> 00:32:27.812
frictional models predict causes
the variability and high

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5710-3
00:32:27.812 --> 00:32:32.007
frequency ground motion, whereas
what I've shown today is that

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5710-4
00:32:32.007 --> 00:32:36.135
the elastic impact model, it's
the size of the structures and

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5710-5
00:32:36.135 --> 00:32:40.263
the geometry of those structures
that predicts what that high

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5710-6
00:32:40.263 --> 00:32:42.593
frequency ground motion should
be.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5758-0
00:32:43.893 --> 00:32:48.592
And so I'm going to talk about
this one observational study

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5758-1
00:32:48.592 --> 00:32:53.681
that actually was led by Shanna
Chu, where we tried to take that

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5758-2
00:32:53.681 --> 00:32:58.301
prediction and tried to see if
there was any observational

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5758-3
00:32:58.301 --> 00:33:02.999
evidence that the that the
impact model might be predicting

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5758-4
00:33:02.999 --> 00:33:04.643
something reasonable.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5817-0
00:33:05.233 --> 00:33:10.174
So what we did was we tried to
uh, first of all, we in order to

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5817-1
00:33:10.174 --> 00:33:14.806
do the study, we basically
needed to design these different

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5817-2
00:33:14.806 --> 00:33:19.669
metrics that corresponded to to
what we expected of the impact

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5817-3
00:33:19.669 --> 00:33:24.146
model in terms of what causes
these differences in ground

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5817-4
00:33:24.146 --> 00:33:24.763
motions.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5845-0
00:33:25.233 --> 00:33:28.542
And as I mentioned before,
there's this structural aspect

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5845-1
00:33:28.542 --> 00:33:32.080
ratio and the average size of
the structures that we think is

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5845-2
00:33:32.080 --> 00:33:33.163
the most important.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5876-0
00:33:33.533 --> 00:33:38.981
And so the first thing that we
did in this study was we defined

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5876-1
00:33:38.981 --> 00:33:43.918
these two metrics that we could
make using a known map of

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5876-2
00:33:43.918 --> 00:33:44.513
faults.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5898-0
00:33:45.033 --> 00:33:49.802
And so with a known map of
faults, we could measure what we

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5898-1
00:33:49.802 --> 00:33:54.013
call the misalignment to do with
how aligned versus.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5924-0
00:33:54.133 --> 00:33:57.652
Misaligned faults are within a
fault network, and this

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5924-1
00:33:57.652 --> 00:34:01.618
misalignment of faults is very
much related to the structural

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5924-2
00:34:01.618 --> 00:34:02.513
aspect ratios.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5943-0
00:34:03.483 --> 00:34:06.404
I just as an example of what
that misalignment would look

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/5943-1
00:34:06.404 --> 00:34:07.813
like in different scenarios.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6038-0
00:34:07.823 --> 00:34:12.365
If you think about these blue
lines as being nominal faults in

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6038-1
00:34:12.365 --> 00:34:17.050
some fault network, umm, if the
two if the faults in some region

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6038-2
00:34:17.050 --> 00:34:20.943
are relatively parallel to each
other, then the fault

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6038-3
00:34:20.943 --> 00:34:25.412
misalignment we would get is
basically zero and if the faults

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6038-4
00:34:25.412 --> 00:34:29.810
are very much misaligned with
respect to each other then the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6038-5
00:34:29.810 --> 00:34:34.135
misalignment ratio would be
relatively high with a bound of

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6038-6
00:34:34.135 --> 00:34:38.172
1 as being the highest number
that you can get and this

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6038-7
00:34:38.172 --> 00:34:41.343
example having a misalignment
ratio of 0.9.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6046-0
00:34:41.493 --> 00:34:43.873
So let's say a very high
misalignment.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6067-0
00:34:44.463 --> 00:34:48.003
I'm and everything in between
gives you fault misalignments

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6067-1
00:34:48.003 --> 00:34:50.303
that are in between those two
numbers.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6076-0
00:34:51.673 --> 00:34:57.183
And as I mentioned, you can take
this, uh metric of.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6094-0
00:34:58.103 --> 00:35:01.587
Fault network complexity that
has to do with misalignment and

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6094-1
00:35:01.587 --> 00:35:03.103
measure it for real faults.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6153-0
00:35:03.533 --> 00:35:09.082
So this is an example I'm going
to the COSO region of California

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6153-1
00:35:09.082 --> 00:35:14.630
and taking the USPS Fault Fault
Fault database and measuring the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6153-2
00:35:14.630 --> 00:35:20.179
misalignment ratio for this COSO
region and what we find is that

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6153-3
00:35:20.179 --> 00:35:24.873
in this region the misalignment
ratio is a value of 0.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6178-0
00:35:25.113 --> 00:35:29.446
MY29, this ends up being
actually a relatively low value

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6178-1
00:35:29.446 --> 00:35:34.083
compared to other regions in
Southern California, which have

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6178-2
00:35:34.083 --> 00:35:35.603
higher misalignment.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6185-0
00:35:35.883 --> 00:35:37.293
Umm, great.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6211-0
00:35:39.103 --> 00:35:42.339
And then the other thing that we
did was we came up with a metric

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6211-1
00:35:42.339 --> 00:35:44.593
that's related to the size of
the structures.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6243-0
00:35:44.603 --> 00:35:48.687
And this one is maybe more
straightforward, just related to

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6243-1
00:35:48.687 --> 00:35:52.703
the density of faults and the
density of fault is directly

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6243-2
00:35:52.703 --> 00:35:55.493
related to the average
structural sizes.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6277-0
00:35:55.873 --> 00:36:00.058
And the example here is below,
where maybe it's obvious that if

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6277-1
00:36:00.058 --> 00:36:04.308
there's very few faults then the
structures between those faults

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6277-2
00:36:04.308 --> 00:36:07.773
are relatively large, so the
fault density is small.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6342-0
00:36:08.333 --> 00:36:12.556
That corresponds to relatively
large structures, and when you

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6342-1
00:36:12.556 --> 00:36:16.643
have lots and lots of faults,
cross cutting through a fault

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6342-2
00:36:16.643 --> 00:36:20.661
network, then the average
structural sizes are quite small

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6342-3
00:36:20.661 --> 00:36:25.020
and this corresponds to a high
density density fault density of

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6342-4
00:36:25.020 --> 00:36:29.039
faults, and again one can make
this measurement on on real

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6342-5
00:36:29.039 --> 00:36:32.921
observed fault networks that we
have, including those in

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6342-6
00:36:32.921 --> 00:36:34.283
Southern California.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6357-0
00:36:35.703 --> 00:36:39.573
So a couple things to note about
these two different metrics.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6417-0
00:36:39.763 --> 00:36:43.608
The way that we constructed it,
we constructed this misalignment

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6417-1
00:36:43.608 --> 00:36:47.216
ratio to be scale independent
and what that means is that if

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6417-2
00:36:47.216 --> 00:36:50.646
you had a fractal network of
faults, then if you measured

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6417-3
00:36:50.646 --> 00:36:54.254
that misalignment ratio at a
large scale versus you measured

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6417-4
00:36:54.254 --> 00:36:57.743
it at a smaller scale, then you
would get the same number.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6419-0
00:36:58.423 --> 00:36:58.853
Umm.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6473-0
00:36:58.963 --> 00:37:03.362
And that's especially important
as we will see later because

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6473-1
00:37:03.362 --> 00:37:07.760
most of the fault maps that we
have are at relatively coarse

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6473-2
00:37:07.760 --> 00:37:12.087
resolution and the the, the
fault zones that we're thinking

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6473-3
00:37:12.087 --> 00:37:16.701
about are actually at relatively
high resolution and they're at

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6473-4
00:37:16.701 --> 00:37:19.513
higher resolution than we really
have.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6497-0
00:37:19.523 --> 00:37:23.414
Good fault maps for so some of
the implications of this work

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6497-1
00:37:23.414 --> 00:37:27.113
are important, that this be a
scale independent property.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6512-0
00:37:28.483 --> 00:37:31.293
Unfortunately, density is not
scale independent.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6551-0
00:37:31.563 --> 00:37:35.217
But if you have a fractal
network of faults, then we know

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6551-1
00:37:35.217 --> 00:37:39.123
how this density of fault number
would scale with the fractal

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6551-2
00:37:39.123 --> 00:37:42.336
dimension, and it scales
actually exactly with the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6551-3
00:37:42.336 --> 00:37:45.423
fractal dimension D if if you
know what that is.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6603-0
00:37:46.903 --> 00:37:51.315
OK, so with that background,
what we can do is then go to a

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6603-1
00:37:51.315 --> 00:37:56.020
place like Southern California,
which has measured or which has

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6603-2
00:37:56.020 --> 00:38:00.285
a relatively good fault maps and
also has relatively good

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6603-3
00:38:00.285 --> 00:38:04.696
measurements of earthquake
ground motions from a variety of

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6603-4
00:38:04.696 --> 00:38:06.313
different earthquakes.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6636-0
00:38:06.703 --> 00:38:11.650
And what we did in this study
that Channa Chu LED was that we

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6636-1
00:38:11.650 --> 00:38:16.516
tried to see if there was a
correlation between the measured

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6636-2
00:38:16.516 --> 00:38:17.553
stress drops.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6651-0
00:38:18.083 --> 00:38:20.635
So these measured stress drops
are actually from corner

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6651-1
00:38:20.635 --> 00:38:21.683
frequency measurements.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6663-0
00:38:22.333 --> 00:38:24.413
I'm and these corner frequency
measurements we think.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6712-0
00:38:25.393 --> 00:38:29.452
Correspond somewhat to how much
high frequency ground motion is

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6712-1
00:38:29.452 --> 00:38:32.876
observed in each of these
earthquakes, or at least it

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6712-2
00:38:32.876 --> 00:38:36.554
correlates with the high
frequency ground motions, and we

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6712-3
00:38:36.554 --> 00:38:40.549
tried to see whether these two
metrics this misalignment ratio

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6712-4
00:38:40.549 --> 00:38:41.563
and the density.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6753-0
00:38:42.033 --> 00:38:46.707
Ratio had any predictive power
over those and as you can see

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6753-1
00:38:46.707 --> 00:38:51.458
here, especially if you focus
just on the green dots which we

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6753-2
00:38:51.458 --> 00:38:55.748
have the most data for,
unfortunately the other regions

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6753-3
00:38:55.748 --> 00:38:57.893
we didn't have as much data.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6768-0
00:38:57.943 --> 00:39:01.833
So it's harder to draw a strong
conclusion based on that.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6853-0
00:39:01.883 --> 00:39:06.316
But just from this Southeast
region of Southern California,

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6853-1
00:39:06.316 --> 00:39:10.970
Umm, we took Peter Shears 2006
stress drop catalog for the for

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6853-2
00:39:10.970 --> 00:39:15.180
the Y axis here and our
measurements of the misalignment

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6853-3
00:39:15.180 --> 00:39:19.391
ratio on the X axis here and
what you can see with these

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6853-4
00:39:19.391 --> 00:39:24.192
green dots in particular is that
there's actually quite a bit of

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6853-5
00:39:24.192 --> 00:39:28.624
the scatter that we can explain
in in terms of the measured

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6853-6
00:39:28.624 --> 00:39:32.613
stress drops being related to
the misalignment ratio.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6857-0
00:39:33.813 --> 00:39:34.203
Umm.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6861-0
00:39:34.513 --> 00:39:35.423
In fact, it's a.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6889-0
00:39:35.433 --> 00:39:39.965
It's a relatively large number,
although the scatter is large,

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6889-1
00:39:39.965 --> 00:39:43.992
so there's approximately a
factor of 10 variability and

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6889-2
00:39:43.992 --> 00:39:46.653
stress drop or apparent stress
drop.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6915-0
00:39:47.973 --> 00:39:51.444
Related to the corner frequency
that we can explain due to the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6915-1
00:39:51.444 --> 00:39:54.583
misalignment ratio and that's a
relatively large number.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6972-0
00:39:54.593 --> 00:39:59.076
So stress drops vary by two or
three orders of magnitude, so

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6972-1
00:39:59.076 --> 00:40:03.853
we're definitely not explaining
all of the all of the deviations

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6972-2
00:40:03.853 --> 00:40:08.189
and stress drop, but we can
explain a significant fraction

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6972-3
00:40:08.189 --> 00:40:12.451
of that approximately this
factor of 10 in going from low

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6972-4
00:40:12.451 --> 00:40:16.713
misalignment ratio to relatively
high misalignment ratio.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6984-0
00:40:18.123 --> 00:40:21.537
Now it turns out that the
density umm also has a

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/6984-1
00:40:21.537 --> 00:40:22.373
correlation.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7018-0
00:40:22.563 --> 00:40:26.162
The correlation is not quite as
good, and actually some of this

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7018-1
00:40:26.162 --> 00:40:29.592
correlation with density we
think actually is because of the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7018-2
00:40:29.592 --> 00:40:32.853
misalignment ratio because they
correlate to some extent.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7044-0
00:40:33.363 --> 00:40:38.677
But there is also a degree to
which the measured stress drops

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7044-1
00:40:38.677 --> 00:40:43.733
correlate with the observed
density of faults in a region.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7073-0
00:40:44.193 --> 00:40:47.928
Unfortunately, this one a little
bit harder to do, partly because

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7073-1
00:40:47.928 --> 00:40:51.323
of what I mentioned before,
which is that, umm, this is not

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7073-2
00:40:51.323 --> 00:40:52.963
a scale independent property.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7111-0
00:40:53.353 --> 00:40:57.498
So if the observations are not
at the scale that we would like,

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7111-1
00:40:57.498 --> 00:41:01.642
then it's it's unclear that the
measurements we make are are as

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7111-2
00:41:01.642 --> 00:41:03.843
useful as the misalignment
ratio.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7155-0
00:41:04.513 --> 00:41:09.110
But in other in any case, we we
do explain a significant amount

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7155-1
00:41:09.110 --> 00:41:13.275
of this variability and so we
think that it's a promising

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7155-2
00:41:13.275 --> 00:41:17.153
thing in terms of the this
impact model having a some

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7155-3
00:41:17.153 --> 00:41:18.373
predictive power.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7186-0
00:41:20.033 --> 00:41:24.278
Umm, one thing that I just
wanted to briefly note is that

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7186-1
00:41:24.278 --> 00:41:28.669
my new student, JSOC Lee, is
doing some work extending this

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7186-2
00:41:28.669 --> 00:41:29.913
to other regions.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7200-0
00:41:29.993 --> 00:41:32.940
Of course, it might be
interesting to note how this

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7200-1
00:41:32.940 --> 00:41:34.583
trend looks in other regions.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7224-0
00:41:35.613 --> 00:41:38.878
Unfortunately, there's not very
many places around the world

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7224-1
00:41:38.878 --> 00:41:41.393
that have as good data as
Southern California.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7280-0
00:41:42.063 --> 00:41:46.565
Umm, but he has been looking at
Japan and Italy, where there are

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7280-1
00:41:46.565 --> 00:41:50.651
relatively good fault maps and
relatively good stress drop

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7280-2
00:41:50.651 --> 00:41:54.252
measurements, and his
preliminary findings are that

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7280-3
00:41:54.252 --> 00:41:58.061
again in these regions this
misalignment ratio can can

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7280-4
00:41:58.061 --> 00:42:02.147
explain a significant trend in
in both of those regions as

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7280-5
00:42:02.147 --> 00:42:02.493
well.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7285-0
00:42:03.223 --> 00:42:05.023
One of the maybe not so.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7311-0
00:42:06.983 --> 00:42:10.796
Optimistic findings is that he
finds that in in both of these

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7311-1
00:42:10.796 --> 00:42:14.485
regions the density of faults
does not have any explanatory

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7311-2
00:42:14.485 --> 00:42:14.853
power.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7315-0
00:42:15.513 --> 00:42:16.003
Umm.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7363-0
00:42:16.293 --> 00:42:19.928
Part of the reason might be
because the observations are

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7363-1
00:42:19.928 --> 00:42:23.434
simply not as good as Southern
California and Southern

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7363-2
00:42:23.434 --> 00:42:26.749
California is is already
probably on the cusp of of

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7363-3
00:42:26.749 --> 00:42:30.766
having the having the resolution
that we need to make a useful

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7363-4
00:42:30.766 --> 00:42:32.933
prediction for these
earthquakes.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7367-0
00:42:34.933 --> 00:42:35.443
OK.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7369-0
00:42:35.513 --> 00:42:36.483
So.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7399-0
00:42:37.093 --> 00:42:40.398
So yeah, so I I've shown that
actually I didn't really talk

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7399-1
00:42:40.398 --> 00:42:43.812
much about what the predictions
of the rough fault frictional

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7399-2
00:42:43.812 --> 00:42:45.023
model would have been.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7426-0
00:42:45.613 --> 00:42:49.733
But basically the rough
frictional model predicts that

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7426-1
00:42:49.733 --> 00:42:53.704
it's primarily due to
heterogeneous slip that causes

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7426-2
00:42:53.704 --> 00:42:57.823
these variabilities and high
frequency ground motions.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7460-0
00:42:58.293 --> 00:43:01.904
But one of the challenges of
using this in a predictive sense

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7460-1
00:43:01.904 --> 00:43:05.340
is that it's very difficult to
predict where there will be

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7460-2
00:43:05.340 --> 00:43:08.193
heterogeneous lip for any
particular earthquake.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7483-0
00:43:08.263 --> 00:43:11.740
Whereas for the elastic impact
model, we can actually quite

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7483-1
00:43:11.740 --> 00:43:15.332
easily observe the at least the
surface traces of these fault

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7483-2
00:43:15.332 --> 00:43:15.853
networks.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7521-0
00:43:16.143 --> 00:43:19.691
And of course, that's not a
perfect measurement of what the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7521-1
00:43:19.691 --> 00:43:23.121
fault networks are doing at
depth, and certainly that's a

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7521-2
00:43:23.121 --> 00:43:26.313
challenge that we need to deal
with in going forward.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7556-0
00:43:26.663 --> 00:43:29.829
But at least we can measure
something that we can then use

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7556-1
00:43:29.829 --> 00:43:32.780
to make predictions for
different regions and how that

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7556-2
00:43:32.780 --> 00:43:36.053
would result in high frequency
ground motion variability for

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7556-3
00:43:36.053 --> 00:43:38.843
different earthquakes from those
different regions.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7569-0
00:43:40.543 --> 00:43:43.163
OK, so I think I'm going to
summarize now.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7613-0
00:43:43.213 --> 00:43:46.782
So I've shown that frictional
models have difficulties

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7613-1
00:43:46.782 --> 00:43:50.351
explaining some of the
observations, in particular how

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7613-2
00:43:50.351 --> 00:43:54.244
high those high frequency ground
motions are, and that this

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7613-3
00:43:54.244 --> 00:43:58.008
geometrical geometrically
complex fault zone impact model

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7613-4
00:43:58.008 --> 00:44:00.473
can explain some of the
observations.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7643-0
00:44:01.383 --> 00:44:05.017
And finally, I just wanted to
leave you with this, that the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7643-1
00:44:05.017 --> 00:44:08.167
impact model has these
significant implications for

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7643-2
00:44:08.167 --> 00:44:11.680
interpreting seismological data
and predicting earthquake

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7643-3
00:44:11.680 --> 00:44:12.103
damage.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7695-0
00:44:12.393 --> 00:44:15.573
Of course, we're far from
knowing that this is the truth,

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7695-1
00:44:15.573 --> 00:44:18.808
but I think at least this
preliminary work shows that it's

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7695-2
00:44:18.808 --> 00:44:22.262
a promising direction to think
about and where we can actually

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7695-3
00:44:22.262 --> 00:44:25.058
have some degree of
predictability for some of the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7695-4
00:44:25.058 --> 00:44:26.483
earthquake ground motions.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7703-0
00:44:26.633 --> 00:44:28.313
Even at these relatively high
frequencies.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7715-0
00:44:29.373 --> 00:44:33.702
So with that, I will close it
and I will take questions.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7715-1
00:44:33.702 --> 00:44:34.233
Thanks.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7722-0
00:44:39.633 --> 00:44:40.533
If anyone still there.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7729-0
00:44:49.273 --> 00:44:50.073
I can't hear anybody.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7735-0
00:44:53.013 --> 00:44:53.633
You why?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7739-0
00:44:54.593 --> 00:44:56.013
OK, OK. Yeah.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7738-0
00:44:54.773 --> 00:44:54.963
Hi.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7749-0
00:45:00.433 --> 00:45:03.533
Hi, Victor, can you hear me
cool?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7753-0
00:45:01.973 --> 00:45:02.093
Yes.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7756-0
00:45:03.543 --> 00:45:04.573
I'm Austin Elliot.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7759-0
00:45:04.583 --> 00:45:05.023
Thanks for the.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7772-0
00:45:06.403 --> 00:45:08.893
Compelling conceptual model that
you presented here.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7797-0
00:45:08.903 --> 00:45:12.473
I'm wondering about sort of the
last stuff you showed the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7797-1
00:45:12.473 --> 00:45:16.289
relationships between calculated
misalignment and density and

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7797-2
00:45:16.289 --> 00:45:17.643
then stress drops the.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7807-0
00:45:17.683 --> 00:45:19.163
So you're looking at the.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7823-0
00:45:19.613 --> 00:45:23.566
Those parameters are calculated
for just the regional fault map

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7823-1
00:45:23.566 --> 00:45:26.283
around the events you're
considering right?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7873-0
00:45:26.333 --> 00:45:31.027
Rather than, so it's essentially
assuming that the event is

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7826-0
00:45:26.503 --> 00:45:26.703
Yeah.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7873-1
00:45:31.027 --> 00:45:35.330
involving the well that the that
the region contains a

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7873-2
00:45:35.330 --> 00:45:40.337
representative distribution of
faults that the event would have

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7873-3
00:45:40.337 --> 00:45:44.013
sort of taken advantage of or
involved, right?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7871-0
00:45:42.443 --> 00:45:42.673
Yes.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7888-0
00:45:44.023 --> 00:45:49.083
And so, have you looked at or
sort of challenge that

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7888-1
00:45:49.083 --> 00:45:50.133
assumption?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7891-0
00:45:50.143 --> 00:45:51.033
Have you looked at?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7903-0
00:45:51.163 --> 00:45:55.303
Maybe events that do have really
good rupture mapping.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7912-0
00:45:55.983 --> 00:45:56.283
Hmm.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7941-0
00:45:56.193 --> 00:45:59.119
Umm, obviously that's a much
more limited data set, but have

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7941-1
00:45:59.119 --> 00:46:02.189
you looked at this in terms of
like for actual events where you

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7929-0
00:45:59.253 --> 00:45:59.453
Yeah.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7941-2
00:46:02.189 --> 00:46:03.483
know which faults ruptured?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7957-0
00:46:03.793 --> 00:46:05.403
Do you see that same
correlation?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7945-0
00:46:03.963 --> 00:46:04.183
Yeah.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7947-0
00:46:06.013 --> 00:46:06.383
Yeah.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7953-0
00:46:06.393 --> 00:46:07.523
So that's a great question.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7987-0
00:46:07.693 --> 00:46:10.731
So first of all, you're you're
exactly right that you know

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7987-1
00:46:10.731 --> 00:46:14.025
we're we're taking these fault
network or these fault maps that

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/7987-2
00:46:14.025 --> 00:46:15.363
are at a very large scale.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8007-0
00:46:15.473 --> 00:46:20.498
So the USGS fault maps on the
resolution is maybe at the 10

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8007-1
00:46:20.498 --> 00:46:22.423
kilometer scale, right?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8028-0
00:46:22.733 --> 00:46:27.131
And the scales that I'm actually
thinking about in this model are

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8028-1
00:46:27.131 --> 00:46:29.463
in the sub kilometer scale,
right?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8056-0
00:46:29.473 --> 00:46:32.853
So maybe 100 meter scale in some
cases even smaller than 100

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8056-1
00:46:32.853 --> 00:46:35.679
meter scale, especially for
these relatively small

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8056-2
00:46:35.679 --> 00:46:36.343
earthquakes.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8060-0
00:46:36.983 --> 00:46:37.383
Umm.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8080-0
00:46:37.883 --> 00:46:43.105
And it's a good point in terms
of trying to get go to places

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8080-1
00:46:43.105 --> 00:46:45.673
that have better observations.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8103-0
00:46:45.883 --> 00:46:49.549
One thing that we have done, we
have looked at the Ridgecrest

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8103-1
00:46:49.549 --> 00:46:51.913
sequence and so in the
Ridgecrest area.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8109-0
00:46:52.623 --> 00:46:54.023
It does seem like this.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8170-0
00:46:54.913 --> 00:46:59.438
This correlation still stands
right, meaning that if you go to

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8170-1
00:46:59.438 --> 00:47:03.962
sub Ridgecrest scales and look
at regions that have regions of

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8170-2
00:47:03.962 --> 00:47:08.198
the Ridgecrest aftershock
sequence on that have relatively

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8170-3
00:47:08.198 --> 00:47:12.938
larger stress drops versus lower
stress drops, that they that the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8170-4
00:47:12.938 --> 00:47:16.672
higher stress drops occur in
regions that have more

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8170-5
00:47:16.672 --> 00:47:18.323
geometrical complexity.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8180-0
00:47:18.613 --> 00:47:20.603
I'm compared to to ones where
they do not.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8217-0
00:47:21.693 --> 00:47:25.864
But as you might have also
implied, there are a very small

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8217-1
00:47:25.864 --> 00:47:30.176
number of data sets where one
can even try to do this study,

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8217-2
00:47:30.176 --> 00:47:33.003
and we really need better
observations.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8241-0
00:47:33.533 --> 00:47:36.856
One of the possible future
directions here is thinking

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8241-1
00:47:36.856 --> 00:47:40.661
about trying to use seismicity
umm to try to constrain some of

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8241-2
00:47:40.661 --> 00:47:41.023
these.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8245-0
00:47:41.033 --> 00:47:41.583
Umm.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8267-0
00:47:42.023 --> 00:47:45.509
Let's say fault networks at
especially at depth, but that's

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8267-1
00:47:45.509 --> 00:47:48.703
still a direction that we
haven't gone into very much.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8271-0
00:47:50.893 --> 00:47:51.483
Well, thank you.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8272-0
00:47:52.063 --> 00:47:52.263
Sure.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8283-0
00:47:55.273 --> 00:47:57.093
Rob Graves, when I meet you.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8286-0
00:48:01.183 --> 00:48:01.693
Yeah.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8289-0
00:48:01.743 --> 00:48:02.253
OK.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8293-0
00:48:02.323 --> 00:48:03.713
I, victor.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8296-0
00:48:04.143 --> 00:48:04.833
Great talk.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8344-0
00:48:04.843 --> 00:48:08.606
Very interesting and I've seen
this a couple times and I'm I'm

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8344-1
00:48:08.606 --> 00:48:12.190
very intrigued by this and
actually what I I you know, I've

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8331-0
00:48:11.163 --> 00:48:11.323
Yeah.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8344-2
00:48:12.190 --> 00:48:15.773
kind of been thinking about well
can we model this somehow?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8377-0
00:48:15.823 --> 00:48:19.907
And I'm thinking kind of from a
kinematic standpoint, so maybe

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8377-1
00:48:19.907 --> 00:48:23.861
not trying to understand all
the, you know, physics, but you

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8364-0
00:48:20.033 --> 00:48:20.173
Right.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8377-2
00:48:23.861 --> 00:48:26.453
know this model that the the
phenomena.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8494-0
00:48:26.943 --> 00:48:31.308
So I'm curious if you have a
like you know, if you thought

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8494-1
00:48:31.308 --> 00:48:35.524
about maybe how you could
represent these using a moment

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8494-2
00:48:35.524 --> 00:48:40.036
tensor for example, you know
what, what would they look like

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8415-0
00:48:38.483 --> 00:48:38.643
Yeah.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8494-3
00:48:40.036 --> 00:48:44.622
and and then a related part or
related to that is you know as

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8494-4
00:48:44.622 --> 00:48:49.356
the say the rupture comes up and
it transfers along these small

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8494-5
00:48:49.356 --> 00:48:53.942
network of faults, would that
also maybe lead to starting and

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8494-6
00:48:53.942 --> 00:48:58.232
stopping of the rupture, you
know kind of on a very small

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8465-0
00:48:57.923 --> 00:48:58.453
Hmm.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8494-7
00:48:58.232 --> 00:49:02.670
scale, so the those those two
kind of questions on when are

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8482-0
00:48:58.623 --> 00:49:02.023
Yeah, yeah, yeah.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8494-8
00:49:02.670 --> 00:49:04.963
you have some thoughts? Thanks.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8490-0
00:49:04.693 --> 00:49:05.083
Yeah.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8496-0
00:49:05.093 --> 00:49:06.943
So both both are great
questions.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8534-0
00:49:07.193 --> 00:49:12.021
Let me try to start with the 1st
about how to include these in in

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8534-1
00:49:12.021 --> 00:49:16.775
a in a model kinematically it's
actually quite easy and it's not

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8534-2
00:49:16.775 --> 00:49:18.823
in terms of a moment tensor.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8577-0
00:49:19.213 --> 00:49:23.356
Each of these impact events is
really like a single force, and

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8577-1
00:49:23.356 --> 00:49:27.696
you could, in a kinematic model,
you know, just introduce a bunch

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8577-2
00:49:27.696 --> 00:49:31.970
of single forces that you would
think would nominally correspond

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8577-3
00:49:31.970 --> 00:49:33.613
with these impact events.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8631-0
00:49:34.043 --> 00:49:37.290
Every time one of these
structures moves from going to

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8631-1
00:49:37.290 --> 00:49:40.832
the right to going to the left,
that is one of these impact

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8631-2
00:49:40.832 --> 00:49:44.019
events and you can try to
include the variability and

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8631-3
00:49:44.019 --> 00:49:47.738
angle that you would expect from
a known geometry of a or some

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8631-4
00:49:47.738 --> 00:49:50.453
expected geometry of your of
your fault zone.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8688-0
00:49:51.063 --> 00:49:55.394
One of the things that I didn't
really mention earlier is that

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8688-1
00:49:55.394 --> 00:49:59.450
actually those angles end up
being quite large compared to

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8688-2
00:49:59.450 --> 00:50:03.849
the average angles of the faults
themselves, and that has to do

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8688-3
00:50:03.849 --> 00:50:07.699
with just how how you get an
impact angle from a from a

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8688-4
00:50:07.699 --> 00:50:09.073
geometry of a fault.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8711-0
00:50:09.293 --> 00:50:11.529
But that's an important thing
that it would need to be

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8711-1
00:50:11.529 --> 00:50:13.723
included if you wanted to
include that kinematically.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8730-0
00:50:14.393 --> 00:50:17.548
And I do think that that would
be a great direction to go

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8730-1
00:50:17.548 --> 00:50:20.103
because one can make those
predictions, right?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8742-0
00:50:20.113 --> 00:50:22.453
One could take a geometry of a
known fault.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8799-0
00:50:22.613 --> 00:50:25.758
One could estimate how
frequently you would expect

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8799-1
00:50:25.758 --> 00:50:28.902
these single forces to occur,
and then add that in

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8799-2
00:50:28.902 --> 00:50:32.847
kinematically to a model and one
of the things that you predict

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8799-3
00:50:32.847 --> 00:50:36.361
to be different from moment
denser model is that you get

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8799-4
00:50:36.361 --> 00:50:40.122
this difference in PTO S wave
energy because of these single

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8799-5
00:50:40.122 --> 00:50:40.553
forces.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8810-0
00:50:42.443 --> 00:50:44.653
So hopefully that answered that
question.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8808-0
00:50:43.313 --> 00:50:43.513
Right.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8832-0
00:50:47.463 --> 00:50:49.393
Remind me what your second
question was?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8822-0
00:50:49.663 --> 00:50:50.073
Yeah.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8827-0
00:50:50.083 --> 00:50:51.183
Sorry, sorry about that.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8843-0
00:50:51.193 --> 00:50:53.733
Yeah, I was just curious if you
had ideas.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8879-0
00:50:53.883 --> 00:50:57.896
Would there be like a starting
and stopping of the rupture at a

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8865-0
00:50:56.853 --> 00:50:59.063
Ah, yes, yeah.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8879-1
00:50:57.896 --> 00:51:01.407
very fine scale that might also
increase high frequency

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8879-2
00:51:01.407 --> 00:51:02.033
radiation?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8872-0
00:51:02.323 --> 00:51:02.953
Yeah.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8874-0
00:51:03.003 --> 00:51:03.313
Yeah.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8892-0
00:51:03.323 --> 00:51:06.218
So that's a great question about
whether this has implications

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8892-1
00:51:06.218 --> 00:51:08.193
for the dynamics of the
earthquake itself.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8951-0
00:51:10.903 --> 00:51:14.513
It's not something that I've
spent a whole lot of time

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8951-1
00:51:14.513 --> 00:51:18.254
thinking about yet, but I do
think it's a very important

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8951-2
00:51:18.254 --> 00:51:22.193
question, right in terms of
trying to understand whether it

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8951-3
00:51:22.193 --> 00:51:26.327
would, let's say as you said,
caused cause earthquakes to stop

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8951-4
00:51:26.327 --> 00:51:29.543
or start again and how best to
think about that.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8994-0
00:51:29.553 --> 00:51:32.361
So I'm not sure I have much
useful to say at this point,

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8994-1
00:51:32.361 --> 00:51:35.315
except that I would be very
interested in sort of following

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8994-2
00:51:35.315 --> 00:51:38.073
up on that to think about what
the consequences for the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/8994-3
00:51:38.073 --> 00:51:38.713
dynamics are.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9008-0
00:51:38.763 --> 00:51:41.412
Right now I've only really
thought about the consequences

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9008-1
00:51:41.412 --> 00:51:42.233
for ground motion.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9006-0
00:51:43.163 --> 00:51:43.573
Yeah.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9011-0
00:51:43.613 --> 00:51:44.373
OK, great.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9017-0
00:51:44.543 --> 00:51:45.083
Thanks, victor.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9015-0
00:51:45.583 --> 00:51:46.153
Yep.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9018-0
00:51:46.203 --> 00:51:46.563
Thank you.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9035-0
00:51:56.913 --> 00:51:59.973
Chris by you never hear me.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9041-0
00:52:01.163 --> 00:52:03.833
Hello that was a great talk,
victor.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9067-0
00:52:04.263 --> 00:52:08.526
So I was wondering about the
depth the the other, the third

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9050-0
00:52:04.693 --> 00:52:04.903
I.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9067-1
00:52:08.526 --> 00:52:10.373
dimension cause the model.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9073-0
00:52:09.473 --> 00:52:09.893
And yeah.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9087-0
00:52:10.383 --> 00:52:13.613
The model is a is a 2D model and
it's a really cool model.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9147-0
00:52:13.623 --> 00:52:16.987
I really enjoyed reading your
papers when they first came out

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9114-0
00:52:16.883 --> 00:52:17.473
Thanks.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9147-1
00:52:16.987 --> 00:52:20.242
and all the exciting work that's
been done on it, but I was

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9147-2
00:52:20.242 --> 00:52:23.172
wondering about the third
dimension because maybe the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9147-3
00:52:23.172 --> 00:52:26.373
there will be effects from
temperature, pressure, chemical

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9144-0
00:52:26.183 --> 00:52:27.183
Umm yes.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9147-4
00:52:26.373 --> 00:52:29.573
reactions, all sorts of things
that can happen with depth.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9163-0
00:52:29.583 --> 00:52:31.643
So I was wondering what you're
thinking about that, yes.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9164-0
00:52:32.543 --> 00:52:33.033
Yeah.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9166-0
00:52:33.083 --> 00:52:33.573
So.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9171-0
00:52:33.633 --> 00:52:34.723
So you're definitely right.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9175-0
00:52:35.343 --> 00:52:36.453
There's definitely.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9186-0
00:52:36.523 --> 00:52:39.513
They're definitely should be 1/3
dimension included.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9222-0
00:52:40.423 --> 00:52:45.147
I will say I haven't really
thought too much about exactly

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9222-1
00:52:45.147 --> 00:52:49.790
how to include the third
dimension in this, except to say

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9222-2
00:52:49.790 --> 00:52:54.913
that, uh, we know that there's
variability in other properties.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9266-0
00:52:55.223 --> 00:52:59.538
So for example, maybe some of
the things you were referring to

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9266-1
00:52:59.538 --> 00:53:03.716
is umm, you know, temperature is
changing with depth and you

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9266-2
00:53:03.716 --> 00:53:07.962
might expect the the how much
seismic genesis there is in the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9266-3
00:53:07.962 --> 00:53:10.153
1st place to be changing, right.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9298-0
00:53:10.163 --> 00:53:14.487
So there, there are all these
other physical properties and

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9298-1
00:53:14.487 --> 00:53:19.027
and you would want to include
the right physical properties in

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9298-2
00:53:19.027 --> 00:53:22.413
this in this model for these
other depths. Uh.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9304-0
00:53:24.723 --> 00:53:25.323
Yeah.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9326-0
00:53:25.333 --> 00:53:28.923
You know, again, I'm not sure I
have much else to say except

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9326-1
00:53:28.923 --> 00:53:32.453
that, umm, maybe I'll say one
thing about the observations.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9328-0
00:53:33.363 --> 00:53:33.803
So.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9331-0
00:53:35.133 --> 00:53:35.663
So what?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9382-0
00:53:35.673 --> 00:53:39.383
What I showed today in the
observational sense, the the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9382-1
00:53:39.383 --> 00:53:43.755
best correlations we can see for
these strike slip faults like in

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9382-2
00:53:43.755 --> 00:53:47.597
California and potentially one
of the reasons for that is

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9382-3
00:53:47.597 --> 00:53:51.703
because of that third dimension,
you know strike slip faults.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9420-0
00:53:51.933 --> 00:53:55.625
We have a a the best observed
constraints on what those

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9420-1
00:53:55.625 --> 00:53:59.843
geometries are in the direction
of slip, which we think are the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9420-2
00:53:59.843 --> 00:54:04.061
most important and unfortunately
for some of these other faults

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9420-3
00:54:04.061 --> 00:54:05.313
like thrust faults.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9478-0
00:54:05.943 --> 00:54:09.086
Umm, it's it's much more
difficult to use surface

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9478-1
00:54:09.086 --> 00:54:12.919
observations to constrain what
we think the right properties

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9478-2
00:54:12.919 --> 00:54:16.815
are at depth, and that's going
to be an important point going

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9478-3
00:54:16.815 --> 00:54:20.963
forward if especially if we want
to apply this model to all sorts

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9478-4
00:54:20.963 --> 00:54:24.293
of different faults and not just
strike slip faults.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9487-0
00:54:24.983 --> 00:54:27.903
But yeah, I guess that's that's
future work.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9490-0
00:54:31.883 --> 00:54:32.163
OK.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9493-0
00:54:32.173 --> 00:54:32.503
Thank you.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9494-0
00:54:33.323 --> 00:54:33.533
Yep.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9510-0
00:54:37.403 --> 00:54:41.393
Picture that was a a cool model
and a great presentation.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9519-0
00:54:42.023 --> 00:54:42.423
Thanks.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9514-0
00:54:42.103 --> 00:54:42.673
Give me.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9567-0
00:54:43.023 --> 00:54:47.896
A lot to think about, as you
mentioned at the outset of your

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9567-1
00:54:47.896 --> 00:54:53.087
presentation, the high frequency
ground motion in the near field

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9567-2
00:54:53.087 --> 00:54:57.880
and the far field is very can be
very effective both by the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9567-3
00:54:57.880 --> 00:55:01.633
source and by by the path and
heterogeneities.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9565-0
00:55:01.983 --> 00:55:02.193
Yeah.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9570-0
00:55:02.003 --> 00:55:03.453
I'll path.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9616-0
00:55:04.163 --> 00:55:09.266
Have you thought about ways in
which the perennial problem of

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9616-1
00:55:09.266 --> 00:55:13.957
separating those two out in
terms of identifying effects

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9592-0
00:55:11.903 --> 00:55:12.023
Yes.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9616-2
00:55:13.957 --> 00:55:19.060
that you could earmark to your
model as opposed to scattering

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9616-3
00:55:19.060 --> 00:55:21.693
effects that you don't consider?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9614-0
00:55:22.673 --> 00:55:23.403
Yeah.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9624-0
00:55:23.453 --> 00:55:24.743
So that's a great question.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9685-0
00:55:24.933 --> 00:55:28.704
In general, a very difficult
problem and maybe the only

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9685-1
00:55:28.704 --> 00:55:33.014
useful thing that I have to say
is that an obvious point, which

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9685-2
00:55:33.014 --> 00:55:37.054
is that if the the closer and
closer that we can get to the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9685-3
00:55:37.054 --> 00:55:41.162
source, the easier it is to
observe these source effects and

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9685-4
00:55:41.162 --> 00:55:44.933
to be convinced that they're not
related to, let's say,

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9685-5
00:55:44.933 --> 00:55:46.683
scattering along the path.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9742-0
00:55:47.233 --> 00:55:51.285
Maybe I'll just show very
briefly this part that I didn't

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9742-1
00:55:51.285 --> 00:55:55.056
get to, which was about the
focal mechanisms and this

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9742-2
00:55:55.056 --> 00:55:59.457
comparison of the observations
used this very dense network in

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9742-3
00:55:59.457 --> 00:56:03.648
Oklahoma, this lasso array that
I think the USGS was partly

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9742-4
00:56:03.648 --> 00:56:05.603
responsible for putting out.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9825-0
00:56:06.083 --> 00:56:09.928
But in any case, within this
lasso array we could see that

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9825-1
00:56:09.928 --> 00:56:14.032
there are these changes in the
high frequency focal mechanisms

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9825-2
00:56:14.032 --> 00:56:18.202
that changes quite dramatically
as you go from low frequency to

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9825-3
00:56:18.202 --> 00:56:22.502
high frequency and the one thing
that relates to your question is

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9825-4
00:56:22.502 --> 00:56:26.737
that for this array actually we
can be quite confident, at least

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9825-5
00:56:26.737 --> 00:56:30.907
for this very small array that
the that this transition and the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9825-6
00:56:30.907 --> 00:56:33.643
focal mechanism is not due to
scattering.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9868-0
00:56:33.893 --> 00:56:37.313
And that's because we can
correct for it using all the all

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9868-1
00:56:37.313 --> 00:56:40.964
of the information from all of
these thousands of sensors that

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9868-2
00:56:40.964 --> 00:56:44.325
we have, which is very, very
difficult to do if you don't

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9868-3
00:56:44.325 --> 00:56:46.643
have this kind of high quality
network.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9912-0
00:56:47.193 --> 00:56:50.743
So I'm not sure that's a real a
good answer to your question,

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9912-1
00:56:50.743 --> 00:56:54.178
but I think we really do need
these high these high density

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9912-2
00:56:54.178 --> 00:56:57.212
observations if we're going to
make some progress in

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9912-3
00:56:57.212 --> 00:57:00.303
distinguishing between
scattering and source effects.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9914-0
00:57:01.453 --> 00:57:01.813
Thanks.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9924-0
00:57:01.823 --> 00:57:03.943
I I think it's it's a very good
answer.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9927-0
00:57:05.353 --> 00:57:05.733
Thanks.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9941-0
00:57:07.133 --> 00:57:10.403
OK, so there's a question online
from Russell Gramer.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9964-0
00:57:10.413 --> 00:57:13.328
Have you looked at maps of
surface rupture to see if the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9964-1
00:57:13.328 --> 00:57:14.963
slip transfer onto branch false?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9985-0
00:57:14.973 --> 00:57:18.408
Does a current restraining steps
and if so, what proportion of

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/9985-1
00:57:18.408 --> 00:57:19.553
the slip is involved?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10001-0
00:57:19.563 --> 00:57:21.691
That is, how much of the
earthquake energy is in the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10001-1
00:57:21.691 --> 00:57:22.253
impact events.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10006-0
00:57:24.543 --> 00:57:25.413
Yeah, good question.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10032-0
00:57:25.423 --> 00:57:30.273
So, uh, have we looked at
different events and seeing how

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10032-1
00:57:30.273 --> 00:57:34.787
they how these potential slip
transfers relate to the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10032-2
00:57:34.787 --> 00:57:35.623
stepovers.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10035-0
00:57:38.303 --> 00:57:38.793
Yeah.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10058-0
00:57:38.803 --> 00:57:42.853
So I've only done a limited
amount of work trying to trying

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10058-1
00:57:42.853 --> 00:57:44.473
to go in this direction.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10072-0
00:57:44.703 --> 00:57:48.276
I I've mostly been motivated by
work that other people have

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10072-1
00:57:48.276 --> 00:57:48.573
done.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10126-0
00:57:48.583 --> 00:57:53.331
So for example, the work from
Mark Swanson, which actually

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10126-1
00:57:53.331 --> 00:57:57.998
very nicely shows that at
basically at every one of these

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10126-2
00:57:57.998 --> 00:58:03.067
uh compressional stepovers you
see a slip transfer that occurs

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10126-3
00:58:03.067 --> 00:58:07.976
during what's interpreted, at
least to be as during a single

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10126-4
00:58:07.976 --> 00:58:09.343
earthquake event.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10147-0
00:58:09.873 --> 00:58:13.122
And so, during a single
earthquake event, you definitely

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10147-1
00:58:13.122 --> 00:58:16.483
have these transitions happening
at this very small scale.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10200-0
00:58:17.433 --> 00:58:21.837
Maybe the question was really
asking about the larger scale

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10200-1
00:58:21.837 --> 00:58:26.313
and that's not a not really a
direction that I have tried to

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10200-2
00:58:26.313 --> 00:58:30.937
go into, but my understanding is
that the geologists do indeed

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10200-3
00:58:30.937 --> 00:58:35.633
see umm let's say uh complexity
and slip related to step overs.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10217-0
00:58:35.943 --> 00:58:39.243
I don't know exactly what the
fraction is that is explained

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10217-1
00:58:39.243 --> 00:58:41.223
with these geological
observations.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10229-0
00:58:49.463 --> 00:58:52.533
I see Tom Hanks has his hand up.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10238-0
00:58:55.793 --> 00:58:58.003
Yeah, let me unmute myself up.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10242-0
00:58:58.453 --> 00:58:59.813
Thank you, Shannon.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10254-0
00:58:59.823 --> 00:59:03.243
Thank you, Victor, for a very
interesting talk.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10297-0
00:59:03.333 --> 00:59:08.513
If we could go back to the very
first slide your your title

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10273-0
00:59:07.813 --> 00:59:08.093
Sure.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10297-1
00:59:08.513 --> 00:59:14.124
slide and and tell me about what
kind of rocks these are and you

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10297-2
00:59:14.124 --> 00:59:18.613
got some very you know fine and
thin wearing there.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10313-0
00:59:19.693 --> 00:59:25.580
Is that due to tectonic
stretching or thinning, or are

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10313-1
00:59:25.580 --> 00:59:29.753
those original sedimentary
structures?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10341-0
00:59:29.763 --> 00:59:33.825
If indeed their sedimentary
rocks, I'm not sure from working

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10341-1
00:59:33.825 --> 00:59:35.423
from here what they are.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10336-0
00:59:36.183 --> 00:59:36.643
Yeah.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10343-0
00:59:36.683 --> 00:59:37.723
So that's a great question.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10364-0
00:59:39.883 --> 00:59:42.454
I don't know a whole lot about
the geology, but I'll try to

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10364-1
00:59:42.454 --> 00:59:43.353
answer your question.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10385-0
00:59:43.563 --> 00:59:46.571
So first of all, the one thing
to note is that the the fault

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10385-1
00:59:46.571 --> 00:59:48.493
zone that I showed in the title
slide.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10394-0
00:59:48.503 --> 00:59:49.833
So this is work from Mark
Swanson.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10441-0
00:59:50.723 --> 00:59:55.824
Umm, there has been basically no
deformation of this fault zone

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10441-1
00:59:55.824 --> 01:00:00.766
since it was seismogenic, so it
was exhumed from depth almost

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10441-2
01:00:00.766 --> 01:00:04.831
entirely intact, and at least
marks Mark Swanson's

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10441-3
01:00:04.831 --> 01:00:08.975
interpretation of this
particular part of the fault

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10441-4
01:00:08.975 --> 01:00:09.373
zone.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10465-0
01:00:09.603 --> 01:00:13.971
Is that it was a single event,
maybe two events that occurred

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10465-1
01:00:13.971 --> 01:00:17.633
to produce all of the complexity
that was observed.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10475-0
01:00:17.803 --> 01:00:20.653
This geometrical complexity
within the fault zone that's

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10475-1
01:00:20.653 --> 01:00:21.103
observed.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10501-0
01:00:22.073 --> 01:00:29.160
Umm, in terms of the foliation,
I think part of it is related to

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10501-1
01:00:29.160 --> 01:00:33.193
it previously being a deeper
depths.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10523-0
01:00:33.683 --> 01:00:39.095
So there was some amount of some
amount of this foliation that's

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10523-1
01:00:39.095 --> 01:00:43.673
related to, let's say,
metamorphism in general, right?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10570-0
01:00:43.733 --> 01:00:48.179
So it's it's it's not all
primary in terms of why you see

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10570-1
01:00:48.179 --> 01:00:53.085
this very fine why you see this
sort of linear trends here, But

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10570-2
01:00:53.085 --> 01:00:57.454
basically all of the deformation
that you see here is is

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10570-3
01:00:57.454 --> 01:00:58.373
seismogenic.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10603-0
01:00:59.733 --> 01:01:02.900
So I'm not sure that explained
answered your question, but

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10603-1
01:01:02.900 --> 01:01:05.905
yeah, maybe I would refer you to
Mark's paper if you're

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10603-2
01:01:05.905 --> 01:01:07.353
interested in more details.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10653-0
01:01:08.043 --> 01:01:12.292
I thought you said that a lot of
the thinning here might have

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10653-1
01:01:12.292 --> 01:01:15.992
occurred at at deeper and
potentially aseismic depths

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10653-2
01:01:15.992 --> 01:01:19.624
where you're getting the
deformation, but you're not

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10629-0
01:01:17.523 --> 01:01:17.853
The.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10653-3
01:01:19.624 --> 01:01:23.736
getting earthquakes, but you are
getting the stretching and

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10653-4
01:01:23.736 --> 01:01:25.243
thinning of the rocks.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10649-0
01:01:25.843 --> 01:01:26.313
Yeah.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10675-0
01:01:26.423 --> 01:01:31.276
So none of the none of the fault
offsets that are observed here

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10675-1
01:01:31.276 --> 01:01:34.763
occurred a seismically, so
there's all these.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10680-0
01:01:35.803 --> 01:01:36.293
Umm.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10740-0
01:01:36.913 --> 01:01:41.694
For example, there's these melt
pseudo tachylyte inclusions that

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10740-1
01:01:41.694 --> 01:01:45.960
you can see related to this
false slip and so it's really

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10740-2
01:01:45.960 --> 01:01:49.491
thought that all of the
deformation within this

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10740-3
01:01:49.491 --> 01:01:53.683
relatively small area is
actually due to seismic events.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10764-0
01:01:53.993 --> 01:01:57.863
And it's just that some of the
earlier imprinting due to

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10764-1
01:01:57.863 --> 01:02:01.800
metamorphism is probably the
reason that you have some of

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10764-2
01:02:01.800 --> 01:02:04.243
this lineations in the first
place.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10762-0
01:02:05.043 --> 01:02:05.503
OK.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10767-0
01:02:05.513 --> 01:02:05.983
Thank you.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10769-0
01:02:06.613 --> 01:02:06.783
Sure.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10799-0
01:02:08.543 --> 01:02:12.724
So we are at time, I'm just
going to read one more question

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10799-1
01:02:12.724 --> 01:02:16.973
in the chat from Morgan Page and
then we stop the recording.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10825-0
01:02:17.693 --> 01:02:21.507
Morgan asked about your teasing
with respect to the last row of

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10825-1
01:02:21.507 --> 01:02:24.783
the observational differences
paid to US energy ratio.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10830-0
01:02:24.833 --> 01:02:26.693
What is the observation things?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10841-0
01:02:29.203 --> 01:02:30.743
Sorry, I'm not sure I caught
that, but what?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10851-0
01:02:30.753 --> 01:02:33.163
What was the observation about
the energy ratios?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10859-0
01:02:33.173 --> 01:02:34.913
The P to swive ratios.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10863-0
01:02:35.653 --> 01:02:35.833
Yeah.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10867-0
01:02:35.773 --> 01:02:38.613
Ah, that's a difficult one.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10891-0
01:02:39.733 --> 01:02:44.787
I'm not sure that there are
really any great observations of

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10891-1
01:02:44.787 --> 01:02:48.183
the unaltered P to S wave energy
ratios.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10895-0
01:02:48.853 --> 01:02:49.283
Umm.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10918-0
01:02:49.973 --> 01:02:53.650
And pertaining to, I think it
was Wayne Thatchers comment

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10918-1
01:02:53.650 --> 01:02:57.073
pertaining to whether scattering
did not play a role.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10971-0
01:02:58.203 --> 01:03:02.445
So pretty much all of the
observations that I know about

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10971-1
01:03:02.445 --> 01:03:06.463
or that people have analyzed,
scattering has played a

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10971-2
01:03:06.463 --> 01:03:11.077
significant role in determining
what the actual observed PT S

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10971-3
01:03:11.077 --> 01:03:15.542
wave energies are and what we
would want to look at is what

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10971-4
01:03:15.542 --> 01:03:19.113
the unaltered pita as wave
energies are before.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10979-0
01:03:19.163 --> 01:03:20.933
Let's say there were significant
scattering.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/10986-0
01:03:21.523 --> 01:03:22.593
It's a good question.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/11027-0
01:03:22.603 --> 01:03:27.478
As to you know what data set we
might want to look at, are there

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/11027-1
01:03:27.478 --> 01:03:32.353
any of these very dense 3D array
data sets that might might have

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/11027-2
01:03:32.353 --> 01:03:37.153
good observations of what those
unaltered PS wave energies are?

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/11042-0
01:03:37.703 --> 01:03:40.563
But that's and I would love to
talk to you about that.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/11047-0
01:03:40.573 --> 01:03:42.003
If you have any thoughts about
that.

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/11065-0
01:03:47.533 --> 01:03:50.163
Every speaker, another round of
applause, and we can't stop the

ba6b7c64-50b1-4dfb-9cf2-bc82dca251b2/11065-1
01:03:50.163 --> 01:03:50.573
recording.