So our first plan; our first item on the agenda was to have us all go around and introduce ourselves. But seeing as they're still 131 people logged in, we probably shouldn't do that if we want to be able to leave today.
Forget the first item on the agenda. So new rule, the first time you say something, just introduce yourself who you are, where you come from.
Hi! I'm Sarah Minson. I'm from the U.S. Geological
Survey in Moffett Field/Menlo Park; wherever we are currently in the move. And your moderators for this evening are Keith and Greg.
Say, "hi" Keith and Greg.
Sarah and Greg.
Okay.
You want an introduction?
Oh, just say Hi!
Okay. So I'm Greg Beroza. I'm a professor at Stanford, currently at an Air Force tactical meeting in Florida.
I'm also co-director of SCEC.
And I'm gonna help Sarah out. I'm Keith Knudsen.
I'm the emeritus of the Northern California Coordinator for the Earthquake Hazards Program.
Thank you, Keith. And so what brings us together today is the expansion of SCEC from Southern California into Northern California and beyond, and this is the Northern California Earthquake Hazards Workshop.
So let's talk community activities in Northern California and the SCEC expansion.
So let's start by talking about the SCEC expansion.
Yuhuda, would you like to talk about that?
Yeah, thank you very much, Sarah. And can I show screen?
You see my screen?
Almost. Yes, we see a fish.
Just a second. I don't. I don't see it.
Okay, let me make it make me let me expand it.
Okay, yeah, so, so thank you. I will present very briefly, rather rapidly, three slides.
The first two slides, and to provide context for the planned expansion of SCEC to statewide coverage, and then the third slide will actually begin to move into next
items on the agenda. The third slide
we list examples of key topics that can lead to productive collaborations amongst statewide researchers.
So on April 22, SCEC submitted an NSF
proposal to develop the next earthquake center with the statewide coverage. The proposal had five key questions that begin with, listed on the left here. It begins with,
"How do geodynamic and other processes load the San Andreas Fault System across various locations and space-time scale?"
Then the next question is, "How do fault zones in the bulk of the crust respond to the loading at different locations, depths, and times?"
Question 3 is, "How does the active fault network in California evolve on different timescales?"
And then "How do the evolving properties in turn exert control on the continuous deformation and ground motion?
Question four is, "How can data analysis and simulations improve the predictability of strong ground motion?
And the last question is, "How can system level modeling and observation improve large earthquake forecasting?"
To address these questions we propose four research thrust
with 12 subtopics in total. The first thrust focus is on observation, and in particular, closing critical data gaps.
And here there is a focus on new fault studies, the dynamics of the shallow crust
using machine learning AI techniques of the type we heard earlier today
and then integrating all of these results to multi-scale community models.
The second thrust is developing rheologies that bridge the multitude of scales and condition both for fault zones and the crust as a whole.
Then the third trust is developing at one's modeling frameworks
the queues, the constituent laws, and constraints based on the community models to perform simulations.
Simulations for integrated tectonic modeling, coupled evolution of earthquakes and faults,
and then an improved estimates of seismic hazard in California. And finally, the last thrust is on improving
predictive analysis of seismicity with various subtopics.
So the fault system in southern California was the focus of SCEC for decades, but with notable exceptions, statewide exceptions that include the community fault model,
UCERF, focusing activities such as REALM and CSEP, and also see CEO activities among others.
These statewide exceptions that have been going on for a long time now
actually, they provide examples of models. How can we develop statewide activities in other topics?
The Statewide extent of the research provides a considerable more and better opportunities, and for the [indiscernible] by just studying portions of the system separately.
Very briefly we know that the San Andreas System as a whole exhibit significant diversity of properties, both geometrical properties of faults, geological properties of faults, starting with mixed affinity, oxide styles changing to continental affinity, and then changing again to
oceanic affinity in the north, and also a diversity of behaviors such as great earthquakes, such as with creeping, such as with [indiscernible] and transitions between all of these sections, so the diversity of these properties and behaviors in the entire system improves the
possibilities to which deeper and broader understanding of earthquake behavior in all parts of the system. Some key hazard related questions
we would like to focus on, together with, collaborators from the USGS and other institutions in northern California, how? What are the probabilities of large earthquakes and damaging strong ground motion in different parts of the plate boundary?
Second general question is, what evolving conditions, and processes of multiple space-time scales allow large earthquakes to occur? And how these evolving conditions are manifested by diverse observable data.
This is obvious relation to focusing. The second question is, what fraction
of the cumulative elastic time energy is released seismically in different areas? We know that there's more creeping in the north,
but there's also something in the south. There's also awful deformation, and we would like to quantify all of those issues better in the next center, together again, with a statewide collaborators.
[white screen, technical issue] So in aspiring, in considering statewide extent, we aspire to give out the understanding of the earthquake system in the plate boundary in California, together with statewide researchers from the USGS
and other institutions. Example of our productive collaborative goals include our first developing improved statewide AI based desktop and focal mechanism catalogs.
We have two great talks about this today from Greg Beroza just now and earlier, [indiscernible] focal mechanisms.
There are some in addition to just the work, there's some important outstanding questions we should consider together as a community.
It can actually open up the questions, how do we test, compare, and rank the different catalogs?
It's not obvious. There's no solution for this at present.
The next topic is extending the following, the example, with the CFM.
Which would be developed further, extending also the same CVM.
CGM to statewide to enable uniform physics based seismic hazard studies.
So here they are like in all other topics. I won't get into too many details, but there are different categories of challenges.
One category is we need to agree on information technology.
That is modern, and flexible, and allow accessibility and visualization.
So there are many issues here, and we also should figure out ways that we can benefit from all existing velocity models and try to develop manage multi-scale models.
This topics will be, I'll say a little bit more about this in the workshop on February 14 for Team's, so I'll leave it at that for now.
Then we want to develop other statewide community models as feasible.
So this includes community stress model, community temperature model, community rheology model, and community paleo-seismic models.
I will develop to different extent in different regions, and that would be a great topics for joint collaborative work.
Now, next, if we have these community models, the next challenge would be very important.
Would be to use community models in different regions to get Digital Twins for regions that we have well developed models and then use the Digital Twins for simulations of both tectonic deformations, ruptures and ground motion. This is very important because some models inherently, are
going to remain incomplete because they're dealing with data that are unobserved or very difficult to observe
such as space and temperature. And if we have validated simulation with Digital Twins, we can, of course, use those results to update a community model, community displacement or temperature models then creatively engage in productive positive feedback.
Next, we want to pursue physics and AI best earthquake focusing using improved catalogues that aim to perform
ETAS and this of course would be accompanied by CSEP testing.
We would like to develop, there's a whole big topic that will require collaborations with everyone who is capable and willing. We want to develop, import physics-based earthquake simulators.
So there are two parts here; one is, it will be important to extend the ask
to become statewide. This is already to some extent in progress, and is doing well.
The next simulator that we want to develop is next generation asks simulators
that accounts for coupled evolution of earthquakes and faults.
That is the fault properties post geometry and material, are evolving as part of the deformation, and we studied the whole system as one dynamical,
the whole behavior in evolution is one dynamical system.
We want to develop also improved physics based probabilities, seismic
hazards, using the updated CyberShake and updated multi-scale community velocity models.
And the last topic I list here before I open it up for discussion or
other topics is we want to work together on community workshops, meetings, and trainings; and good examples that we have to continue our
workshop from dynamic rupture that were very helpful in benchmarking calls.
The recent workshop that we had tag actually is that we had on strip strength of validation and workshop and training on ground motion modeling.
So I have more, but I'll stop here and open it up for bringing it back to the moderator.
Bring it up for discussions.
Okay.
Excellent. Thank you so much, Yehuda, and I will just say, don't worry to the audience, don't
worry quite yet about understanding all the CXMs. Up next, we have Noah and Scott to talk about them in more detail, but perhaps they can now ask Greg to entertain questions on everything else.
Sure. So questions from the group about the proposal.
Looking in the chat. There's specific questions, but nothing really focus on the proposal I'm finding yet.
Oh, I'll ask a quick question. This is um, I'll
turn on my video I'm Jonathan Dolphin, a system
professor Purdue University. It look like you guys are really focusing on the transform deformation.
Are there plans to kind of leave the subduction related area out of this proposal?
We plan to collaborate with the parallel initiative that was developed to study the subduction zone. So we are not.
We don't intend to leave it altogether.
No, The answer is, no, but we do plan to focus on the transform plate boundaries and in the region which overlaps with the subduction to do research.
Most in our center, as well as to collaborate with the other centers.
Got it. Thank you. Go ahead.
Yeah, the boundaries are as as mentioned, as Jay mentions in the chat.
The boundaries are not black and white, so it would be a natural point of collaboration between people studying seduction zones.
And this more transform focused center to collaborate because the systems should interact.
Yeah, and I also want to add to this. So we have always had global activities actually, it was never limited to the focus nature [indiscernible]
but there are clear differences, the tectonic differences, you know, between the transform and the subduction.
So we will study this as well. We study that as well, but it will be focused for another center
Probably.
Okay, perfect. Thank you.
Thank you. So other questions or comments.
So there's one from Alex Hatem. How will the seismic hazard stress overlap with USGS efforts? Collaborative?
Or with SCEC? Or will SCEC lead a more research oriented effort.
Hear that. You want to speak to that?
Yeah, so, I will speak to this briefly. So the short answer is, Alex, we don't know.
We have not worked out the details as we would like to collaborate.
Of course, and working on all of the topics that I listed will have to be worked out by multiple [indiscernible] working on that.
We will decide together what is the best approach to address any or any and all of those topics.
So I'm not giving you a direct answer, because there is no clear plan, it is
all flexible and we will need to work on all of this together.
Cool. Thank you.
So Mike Oskin points out in the chat, Mike, you want to unmute and make your point.
Sure. I just wanted to add on to Yuhuda's point about collaborating at the boundary with the subduction system, that the Triple Junction region is an important area for understanding how the transform plate boundary evolves.
It's essentially the template for what's happening further to
the southeast.
Yeah, right.
Thanks.
There was a question in the chat if the proposal was already submitted.
The answer to this is yes. It was submitted in April 2022,
This is Zia Zafir which I had a question. So already submitted,
which means you already have submitted what you are planning to do, so, you know what you're gonna do, are you going to lead, you're gonna collaborate,
So all of those things are already submitted.
So I think you have a good answer right now. Right? You can answer those.
No, we submitted for propose research, proposed studies, but we did not,
and we have been collaborative from the beginning, and we plan to continue to be collaborative.
But we did not work out all the details of the collaboration ahead of time, so...
And let me just add that we, you know there are limitations in the USGS
ability to be involved in proposal development for another Federal agency.
So we had to work around those.
Okay.
But we certainly wish to collaborate simply from the fact that the problems are very difficult, very deep, and we need, you know, the best available data, the best available people.
Oh, precisely, we will collaborate remains to be worked out and we will be open to suggestion of productive mode of collaborations.
Right, and I would add that people from the USGS have been deeply, and including people from northern California who are on this call have been deeply involved in SCEC leadership, and we imagine that will continue.
We hope it will continue.
Well, I personally think these questions about you know how should this collaboration work, and what should the plan be going forward
is the single, most important question, and it is on our agenda as the last item on the agenda, so perhaps you should move along so that we have the proper time to answer that important question.
Fair enough.
So to that end can I bring up Laurent Montesi and Scott Marshall to talk a little bit about the SCEC community models.
Sure. Let me share my screen and get stuff going if I'm allowed, I am allowed. Yay.
Okay, that's not the first side. That's the first side.
Okay, so what everybody can hear and see, right? Yeah. Okay, good.
So what Lauren and I are gonna do is we're going to cover,
Give you an overview of what the community models have currently and a little bit on some of the methodologies.
But keep in mind that as co-leaders of the community modeling group, our task is basically to assist these different developers with, you know, disseminating their models and getting them out to the public, so we don't actually build all of these ourselves. So first thing,
you should know is all the community models fall under the CXM.
umbrella where X means anything, community fill in the blank model, right?
So these are all available at the URL, right there. The SCEC.org/research/CXM, and you can click on them and browse and look through all this stuff.
I mentioned the umbrella. Here's the literal incantation of that, if you will. Under the CXM umbrella, we have a fault model, a geodetic model, a rheology, model, a paleoseismic database which breaks the pattern but
that's okay. A stress model, a thermal model, a velocity model,
And then a software platform that integrates lots of velocity models.
So we have a lot of different community models. All of them are at various stages of development.
Some of them have been around for almost 20 years. Almost?
They've been around almost 35 years.
So, I'm gonna start with the community fault model first, and I'm gonna talk about some of these, and then Laurent will take over and he'll discuss some of them.
Just so we're on the same page. The community fault model is different from UCERF,
it's different from the USGS Q faults, and not plotted here.
It's different from the national seismic hazard
update the 2023 model. It's different from all of those things.
The community fault model is fully 3 dimensional. It's as complex as the geologic and geophysical data dictate.
So when you see a simple model in the community fault model, you know that that fault has very little data constraining it.
But these models are all different, but in some ways they all are sort of based on each other, and are built off of each other.
So default model right now is in version 5.3, although version 6.0 is finished.
We're just working on some of the IT stuff to get it released.
That is the result of a community evaluation for something like 30 SCEC participants evaluated the model and the highest ranked
faults became CFM 6. This is the figure at
the right over here shows you what the CFM looks like in 3D.
However, you have to have specialized software to see this. So what we did is we developed a set of web-based tools that allows the user to browse a map-based interface
that's interactive sort of like a Google map and you can browse and download the model individually,
you can see seismicity, or you can actually click on individuals fault and hit the plot option and actually look at the faults in 3D without having any specialized software.
So that's pretty cool. I would encourage you to go see the CFM
homepage and then there is a link to the the download and viewer tools.
I think one of the topics we wanted to talk about is how these models are built.
So I figured I would talk about the CFM.
The CFM is not built using a uniform methodology because the data is not uniform.
The data that we have for constructing fault models is extremely diverse.
So, for example, this is the Ventura fault model, Pitas Point fault from Judith Hubbard and others.
paper that fault geometry is based on several cross sections of seismic reflection data, oil industry,
well data, stratigraphy, surface trace locations, field mapping, everything!
And we put this into three-dimensional CAD software.
And we basically fit a three-dimensional surface to the data.
So this kind of method is how most of the faults in the CFM
are built. Unfortunately, when you build faults by hand like this, it's not possible to automate, and you can't put an error bar on these things because a lot of these things are interpretational.
But I think this is still a good way to build fault services, because it integrates the most different kinds of data.
There are cases where we can automate this at least semi-automate it Reisner et al. wrote a paper in 2017, where they showed, if you have a system that has a lot of seismicity and focal mechanisms, there is a semiautomated method for
producing faults. So the Ridgecrest sequence was used to develop the community fault model representation of the Ridgecrest fault system, which is quite complicated, and this is objective
and it's based on a semi-automated method.
However, to use this method, you need a lot of seismicity and a lot of focal mechanisms.
So this kind of method really is only possible in areas with a lot of seismicity.
We also have Community Velocity Models, I think the official Community Velocity Models are the CVM-H,
for Harvard and the CVM-S4.26.
But there are actually a lot of really smaller scale models with high resolution
if you see the basins over here, and here's sort of a map figure showing the different CVM and where they are spatially.
So what the UCVM platform does is it allows a user to integrate all of these models into a single velocity model, using various smoothing platforms.
And so the velocity models are available through the SCEC web pages. And so is the UCVM software platform, which is very powerful.
We have a new Paleoseismic database coming this year.
It's getting close to being done. The source data for it is basically the National Seismic Hazard Map update in 2023.
So Alex, you heard asking some questions. So it's myself, Akciz,
and Alex Hatem actually sorry I said his name wrong, Alex and we're putting this together.
And the idea is basically to have as new studies come out, we want a place for this to live.
So it's interactive and new studies can be added to it easily.
So this will contain slip rate estimates and event chronologies.
We also have a geodetic model. Here's a box showing basically what the geodetic model covers.
Although Mike Floyd tells me that for GNSS data, I think basically all of California is not covered.
That's mostly automated. But the cool thing about the geodetic model is the integration of InSAR for version 2 that's planned to be released this year
I think. The group basically took a bunch of different InSAR tracks from sentinel data and used all kinds of different methods and then sort of average them.
And what they found is this dramatically decreased the errors and made the data much more robust.
So CGM-2 is really quite the thing. And I think when it comes out everybody will be happy to use it.
The GNSS data, though, there's several different processing centers that where you can get GNSS data for basically all of California.
CGM, has a web page on that web page we try to do with most of our SCEC products is package them in a DOI,
So it's citable. So we're typically using Zenodo.
So version 1 of CGM is available through Zenodo and so is the Community Fault Model.
And so is the Rheology Model. So if you go to these home pages you'll see them there
please reference them, it's our way to sort of give people credit for putting the time into the developing
these models. Okay, Laurent's gonna take over and you can share your screen, or I can just switch the slide when you say next. If you want.
I just ask you to switch the slide. I think it's gonna be faster that way.
Okay.
Yeah. I'm Laurent Montessi from the University of Maryland, and I will be talking to you a little bit about the various components of the CXM that have maybe a little bit further from data, and now more like interpretation and kind of models in that sense.
And the first one probably is the most complex of models we have, which is the CSM, that's stands for the Community Stress
Model. And this one is actually a collection of various estimates of the stress field or the stressing rate field in California, in southern California, you see, we have 6 stress models, 7 stress same rate models.
All of them are based on different data sets and different assumptions, on different theories, etc.
They are just been put together on a consistent format and grid, and are all available individually on the SCEC websites that have been mentioned earlier.
What I'm showing there essentially is an average of those various models of auto replaces
if you want to have that kind of one vision of those various components,
all of them are available through the SCEC website. Next, please.
Then, we're gonna move towards what we call the Community of Rheology Model, and that one is essentially built on the top of several models.
Like, I said, we're going further and further in the abstraction level.
One of the things that the CM is built on is what we call a geological framework.
Sometimes it's like GFM, the one that doesn't actually fit the actual templates.
As you can see, the way it is done there is that it's a structural representation of the structure of southern California, where they have been 23 lethal tectonic provinces that have been defined over the region. For each one of them
we have a column stratographic column through the entire lithosphere,
so it's a fairly natural, you know, very broad scope type of story we're not looking at the details of the stratigraphy, as has been mentioned earlier today, but in our case we're looking at the broad, the strategies at various level of the crust and in the
mantle. You can see there to the kind of columns for some of those models, some of those blocks and the colors correspond to certain rock types or the lithology which are defined just by assemblage of minerals. Next please. The next element
there is the Community Thermal Model which has been developed largely by Wayne Thatcher and Vic Chapman, which is very similar to this geological framework,
but thinking about temperature structures. So they define 14 regions of constant heat flow, and for each one of them they have developed a geotherm that is kind of a representation of that place.
Most of them are at steady state when a few of cases there are some transient thermal processes that are included. We actually distributed an alternative version that was developed by Billy Shinevar, which is more an interpolation is not really block based,
like the CTM is, but, on the other hand, only includes thirty-state profiles,
so it may be less realistic in some locations, but smoother throughout the entire region.
Next, please. And on top of those two you can see... the next slide
please.
So on top of those two we have what we call the CRM, the Community of Rheology Model.
At this stage, it's essentially providing an estimates of the ductile flow,
the ductile rheology at each place over the study area. The ductile rheology is obtained by mixing mineral specific lab-derived flows, for various minerals, and they are assembled to make the rock types that are forming the geological framework and if you take the temperature from the
CTM and a strain rate or stress estimate
then you could calculate viscosities. So we have there, for example, views of the rheologies, temperatures, and discussed here are different
depths 2424 meters.
The parts on the right kind of shows blocks that have similar properties.
If you start to think about share localization and things like that.
Next, please.
[noise] I think there's a delay.
Now some of the plans that we are some of the current developments are include reconciling some of the definitions we've heard, for example, earlier on northern California, how they have some different instance of comparison about velocity and a structural models.
We are also looking here other various blocks and definitions.
CTM and so GFM can we become by them.
We can start to use some of this rheology to compare the predictions in viscosity from those rheology models with information such as processing deformations that the 4 panels you see on the right. And kind of use this to develop a new stress model that could be added or
combined, or evaluated against the CSM
that I've mentioned earlier. Next. I think this is my last slide, which kind of emphasizes something that Scott already mentioned earlier, is that most of those models are available, not just the data set itself, but also to some viewers you mentioned.
The CFM one default models is our snapshots of 2 other viewers on the left for that geological framework that I mentioned.
There is a blog that is highlighted here, and you also have like two little markers and of course you cannot see it.
But at the bottom of the screen cannot read it, but at the bottom of the screen you have, which rock type is there? What temperature?
Web velocity, etc. On the right we have a snapshot of the community
the modern velocity viewers which can be using 3D.
You can make cross-sections, and all of those things.
So we've actually worked on trying to make the model easily accessible.
And today can be acquired also through those interfaces, so that they can be reaching out to the [indiscernible]
populations, in range of scientists as possible. I think that's what the last slide.
Thank you.
Thanks, Laurent.
Thank you. So I think we should go straight on into Keith with the help of Roland, was pretty neat
the big picture how all the models across the State look together! So maybe we should just go straight to that, Keith, if you want to take it away.
Okay, I'm not great at sharing screen in zoom, but I'm gonna do that right here.
So you should see a table. Is that correct? Okay, great. Okay.
So we're heading into the less formal part of this.
And hopefully this, I put together with a number of others, will help trigger discussion on the theme that was really in the chat.
As the SCEC representatives were speaking, and that question is, well, how are we going to integrate or unify or work together
essentially with the existing models in the North, and the existing miles in the South, and so 24 hours ago, I started this table and shared it with a number of others who have collaborated on trying to populate it.
And it seems like we need something like this to understand what's going on in the opposite part of the state from each of us.
So, we could do a variety of things
now we could spend time just trying to populate this. I think that might be a little bit awkward, although people could certainly put things in the chat.
The first question on the agenda, after my little slot on the agenda was about continuity of methods between North-South Community models.
So if we wanted to focus on a discussion topic, we could try to populate that column in this table.
I'm willing to serve as a scribe, and I'm sure others who have access to this Google sheet would be willing to do the same if people want to put things into the chat about suggestions for what goes in different boxes and again, what's in this
is very fresh, and certainly needs lots of eyes looking at it, and and the corrections made.
But I thought this would be a start to the, to the framework of the question, well, how are we gonna have integrated models and can we have integrated models?
And what happens at the boundaries? And that sort of thing, and in fact,
what do we have in the North and in the South? So got a variety of different,
we start off with models, but I realized, as we were proceeding through this, over the little bit, we started including databases, too.
So there are 3D velocity models or faults. In the North,
I think we have done a lot to try to characterize creeping faults, and we have data around those.
There are a variety of different seismicity databases essentially.
There are, I think, multiple databases of repeating earthquakes in the North.
We just heard a little bit about the the paleoseismic and slip database it was developed for the National Hazard Model, and sounds like that's already being turned into a SCEC CXM model.
We heard about the rheology model, which I don't think we have an equivalent to in the North.
I think we both have geology models. In the South,
there are rapid fault association being made. I think there are a variety of different crustal velocity and geodetic models in the North and the South.
Ones I tend to think about are the ones that the national side of the hazard model relies on for
It's work in both areas. We have basin sets.
We just heard about the stress model
in southern California. I'm not aware of an equivalent model in the North, not aware of a thermal model in the North.
I think that SCEC has with all these computer science and IT professionals has developed great sets of tools for visualization and querying.
And we don't have that really in the North. The geologic slip rate, compilations. I think
Alex added this in and I'm not sure who added the geodetic deformation models.
There are a range of them, but I think we need to operationalize them.
And then one area where southern Californians are really ahead of us is with hats.
Well, I think we need to come up to speed on that
category. So,
well, it really depends on what people want to do.
We could try to correct errors in this, we could populate it.
We could talk about the continuity question.
This is my contribution to this meeting.
So, Keith can you clarify the continuity you said continuity of methods?
Is this really what you mean? Continuity of methods is this what you really mean? or continuities of data, sets of models?
That's a great question, I guess it's probably both, Yahuda.
I think, yeah, I think it's both.
So.
But, the obvious question is, there are boundary faults between the models in the north and the models in the south
in most cases, and is that due to different methodologies?
Is it due to different platforms? Is it simply resolved by just shifting
geologic boundaries on a geologic map, for example.
So I'll just say, I see Davis is in.
I'll just make one quick comment. I won't solve the problem right now, but it's also in part result with the results of different data coverage actually, which would produce these natural boundaries.
And I think one of the topics we would like to work on together.
We should work on is first improving locally at each place the existing models, led by the people working on this before, so this should continue, and then we should address the continuity problem by developing methodology to merge models.
That is, eliminate the boundaries. That's what I mean by merging, but this is quite complicated, and probably will require machine learning techniques.
So I will not continue. But it's a great research topic, actually.
And, then I want to say that all of the models in different regions and the merge models must be validated.
So we need to validate. We need to develop this iterative loop of developing improving models.
Locally validating, locally merging and validating, you know, etc.
It's a spiral. Hopefully.
Yeah, merging models ain't that easy, right?
Even just with 3D velocity models,
There are atomographic models, and their are geology-based models.
3D-geology based models, and even in northern California we have parallel sets of those two kinds of models, and getting those merged is a challenge, so merging what is primarily a 3D
geology-based model in the North with what is primarily a tomographic base model in the South is...
Yeah, I'm not sure you can just merge those.
So we need to develop techniques to link, to test, and rank models based on their performance.
All models are developed with best intentions,
but how do we know that they actually perform? We need to validate.
Yeah, and test, it also would apply to the catalogs.
There are many, many catalogues now for the [indiscernible], for example,
Greg talked a little bit about this. How do we know, so we don't know.
We don't. These are our open questions, but I think it should be part of the research platform to test, validate.
compare, rank and then make decisions. You know what to keep and and how to merge.
Yeah, it's a good,
it's a rich question, it's an important question, not just for for SCEC, not just for California, but globally
there are people working on merging models. So we we have a couple of hands up.
I'd like to call on Dave Jackson.
Yes, thanks. Can you hear me?
Yes, we can hear you.
Okay. Good. I think it's true that by, I think all of our agreement that the real target for all of this work is a scientific approach to estimating seismic hazard and risk.
And so turning all these things into a kind of earthquake forecast, it's on different time scale, and you know some different geography are really important, and I think it's well worth looking at
what happens in the UCERF3, and you know what's now becoming an extension of that, because they made a very concerted effort with a lot of talent
to accomplish this job of turning, you know the kind of information we have about earthquakes and stress and everything else
into earthquake forecast, and they've done a lot to try to bridge the boundaries between northern and southern California. So, I think it's kind of a review of how it worked and what have been the real successes and what have been some of the problems.
And I think some of the problems are complexity things that took a lot of duct tape to paste together.
But nevertheless it's, I think, a really monumental prospect, and certainly, you know, we've heard the UCERF3
results quoted many, many times already in the last two days.
So that's my recommendation to spend some time looking at how that worked.
Like I can comment on that. The UCERF3, the fault model used in UCERF3 is lacking in northern California.
It started with the CFM, and that was migrated into a state FM,
and then northern California, or I've talked to Andreas and others about this at nauseam
really. The same level of attention needs to be devoted to the fault model
in northern California.
Yeah, so, in the chat Russ Graymer says the point that we should use the information, emphasize the information that's most reliable,
where it's most reliable. So you know, if we had the model and their uncertainties, we can sort of combine information in the Bayesian framework, or something like that, either formally or informally. Scott I think you've had your hand up for a while.
Yeah, thanks. So, SCEC is an interesting organization, right? Because it's investigator driven.
So a lot of these things that are on the spreadsheet in front of us that are, you know, termed southern California, may actually have proposals in for all of California.
I know, for example, I have a proposal in that involves expanding one of the community models to all of California.
Actually two, but those are all pending right now, so we don't know.
But with the last year, the bridge funding at SCEC, we had some flexibility to look to the future and expand.
So at least a few of the CXM models in California have pending proposals to expand statewide. And Keith,
we do have a statewide Community Fault Model, that is included in our proposal to actually formalize it.
And the the tricky part of the Community Fault Model is, once you build the fault, then you have to have all of the data structure stuff like all the metadata, all the everything has to be tidy and neat, or else none of the tools work so the model itself is actually already built through
collaboration with this group and others, but formalizing it and getting into a product that's publicly released is gonna take the effort
and that's what the proposal focuses on.
Well good luck with your proposals, Scott. If you need help identifying people to collaborate with in northern California, I'm sure there are many people in this meeting that would jump at the chance.
Yeah, we have routine, the Community Fault Model group has probably a couple of times a year,
we meet with the UCERF group, people that we think are concerned, and some people have reached out to us to encourage meetings, and we've done that.
So we know that there will be, that whatever we release for the version, one of northern California will just be a starting point, you know that the first thing about a Community Model is just get it out there
So people can improve it. No Community Model is ever finished.
Yeah, so that's an important point. And another important point you brought up was the investigator
driven nature of the SCEC enterprise. And so all these things that we're contemplating are gonna require champions like Scott and Laurent for the Community Models to do the work and carry them forward. Laurent.
Like in the chat, for example, Hal was mentioning an attenuation model, why don't we have one?
Maybe because nobody wanted or proposed to do one at this stage, and there's something that can be added.
Also, I want to point out that a lot of those models we described have alternative versions embedded into them.
For example, you know the velocity models have some of them of the basins, some of them don't.
There's several variations. And I think that's important, because I think you mentioned that [indiscernible] spaces
you will have better constraint for one approach compared to another approach.
Whatever model you're looking at, and that's exactly why we have an alternative realization of a lot of those models.
And so that's brings up the idea that we try to be flexible.
And when we say Community Model, we don't try to get like one answer for everybody, at least less and less
we try to get to that one. And so for everybody, but more like the collection of answers that should be helpful for everybody.
Yeah. And then that probably better represents a true state of knowledge.
So we have. Ian Pierce.
Yup!
Hey? Can you hear me? Okay, it's so. My name is Ian Pierce.
I'm currently a postdoc in Oxford, in the UK.
I'm in Santa Cruz right now, actually.
I wanted to say, I think this is a really good opportunity with SCEC expanding to northern California, to kind and this is based off some conversations with other from the paleoseismology and an earthquake geology community and building off of what Chris Madrugo brought up
in his talk yesterday about, you know there's some some data priorities for specific faults, but I think one of the things from that paleoseismology perspective would be to try to organize maybe a workshop early on in this new SCEC to identify exactly what priorities we have
for either, you know, updating work that's been done with new methods, or where we have big data holes and seeing what those priorities would be.
Because, you know, looking at the impressive, really impressive amount of work that's been done all over the State.
But in southern California we know a lot more about a lot of faults than we do in northern California, and I think that's a good opportunity to expand that.
Yeah, that's a good point, I think,
and Yuhuda can correct me if I'm wrong.
I think there's an explicit effort in the proposal to fill observational data gaps as part of SCEC's strategy.
So that would be one type of gap.
Yeah.
Yeah, I think that gets into the thrust objectives.
So, yes. And let me just say that this table that we see the spreadsheet that we see, I mean, I fully agree with you.
Yeah, we will need sets of workshops...
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