Good afternoon, everyone, and thanks for hanging in to the last presentation
of the last session of our Earthquake Hazards Workshop.
I’m Keith Knudsen of the USGS, and I’m going to spend a little bit
of time talking about USGS earthquake response.
I’m going to cover really three main topics.
The first is the abundance of data that’s available in the seconds, minutes,
and hour or two after an event occurs. Secondly, given that all that information
is available, I believe our earthquake response has really changed over the
last decade or two and that our response now should be governed by trying to
answer questions about earthquake phenomenon – outstanding questions.
And I’ll go through some of those questions.
And then, third, I’ll talk a little bit about collaborating
and partnering and how to plan to collaborate.
So first, what are the goals of earthquake response for USGS?
The first is to provide situational awareness.
And we know that a wide range of audiences are interested in learning
what we can share about a recent earthquake.
Second is to collect perishable data to document
the earthquake effects and impacts.
Third is to better understand hazards and risks so that we make better
forecasts and products. Again, are there outstanding questions
about how earthquakes work, and can we design our post-earthquake
response investigations to try to answer those questions.
And the last goal of USGS earthquake response, which I think is often
not considered in decisions about how to respond, is giving our scientists
and technicians and others a chance to see what happens in an earthquake –
to have that experience. People work for decades in earthquake
science and may only be around for one or two big earthquakes.
I’m sure that many of you – probably all of you are familiar
with our event pages. This shows these events pages.
This one is for the recent Petrolia, California, earthquake.
And these event pages show the plethora of available data and analyses
that are available in the seconds, minutes, and hours following
an earthquake. From earthquake early warning to ShakeMaps, to PAGER,
to interactive maps showing seismicity before, during –
or, before and after an event. These red rectangles highlight three
of our newer products. There’s aftershock forecasts, which I hope
many of you are familiar with. There is ShakeAlert, which is a project
whereby we attempt to warn people that they will be shaking while
that shaking is going on elsewhere and headed their way, and last is
probabilistic maps of predictions of where liquefaction and
landsliding likely occurred given the magnitude and location.
And this figure, borrowed from Dave Wald, shows the timing with
which those various products are released, starting with probabilistic
seismic hazard assessments and development of scenarios in the
between-earthquake times, to ShakeAlert and our ENS
notification of location and magnitude of earthquakes,
to ShakeMap, which is one of the first sort of data-intensive products
to come out, all the way out to our aftershock forecasts and ground failure
predictions that typically come out within an hour or so.
And I think this is – this suite of products represents tremendous
progress we’ve made in recent years and over the last decade or so.
Given that this suite of products is available, I contend that our earthquake
response should have evolved from collecting the kind of information that
goes into those products to trying to answer outstanding questions about
earthquake processes and phenomena. And I’ve spoken with colleagues in
recent weeks to come up with a list of those outstanding questions,
and these next two slide, I – two slides will be used to
go through those outstanding questions.
So the first is, of course, how do different types of structures
respond to shaking. For example, a retrofitted building compared to
a non-retrofitted similar building, what’s the relative performance?
What was the shaking at sites where landslides or liquefaction
or building and other infrastructure damage occurred?
And can we characterize that shaking as a function of frequency?
What factors contributed to the fact that there were damaging ground motions?
Were there source effects or directivity –
path, site, basin, resonance, topographic, etc.?
And are these factors predictable?
How did people and react to and receive, or not, I suppose,
ShakeAlerts and our other products?
And relatedly, what caused the injuries that were –
that occurred, and deaths, for that matter?
The next question would be, how spatially variable are
ground motions in any one event, and why?
And then last on this slide – I’ll go into one more slide,
were there precursory signals or changes, like foreshocks or changes
in creep rate or other phenomenon that we might have identified
beforehand that would tell us that something big was about to happen?
And how do we go about identifying these potential
precursors and evaluating them?
And, if we do identify them, what do we say, and to whom do we say that?
Some more questions about earthquake processes in general that should guide
our earthquake response. What is the temporal distribution of slip?
I’ve got a number of bullets under this that I don’t have time to go through.
Relatedly, what is the spatial distribution of slip?
And by that, I mean both along-strike and perpendicular to strike.
And I’m talking about slip at the surface here.
Why do aftershocks occur, and where and when they do.
I’ll read that again. Why do aftershocks occur where and when they do?
And, relatedly, what might control triggering of additional large events?
Where do ruptures start and stop, and why?
This is a question that we try to answer with our UCERF project
and mode of analyses. And then, lastly, what is the extent
and magnitude of ground failure? And by ground failure, I mean
liquefaction and landsliding. You’ve probably seen me stand up
in meetings and urge people to collect and compile complete maps of where
ground failure did and did not occur because we need such maps for
validating and testing and calibrating our models.
Okay. The last part of this is planning for future earthquake response.
I think each of the regions in the USGS Earthquake Hazards Program
has some form of planning where they’ve got an org chart or a call-down
list or lists of people who they think will be involved, and this is – this is
our northern California earthquake response organization chart.
I’d be happy to share this with others, and I urge those of you who are
thinking that you’ll collaborate and partner with the USGS in future
events to contact those individuals. And you can use those individuals
who do related work to what you’re interested in doing.
And you can use this organization chart to go – to identify
who those people are now. This is sort of a moving target.
It’s always – the names in the boxes are always being changed.
And the colors of the names correspond to their location
within different offices of the USGS.
The top part of that shows sort of the liaison roles.
Some of you may represent agencies that our folks will be representing us
in conversations with you following the next earthquake.
And then these are the sort of investigative sub-disciplines.
We’ve got field operations on the left.
We’ve got collection of geospatial information in the light blue.
The green shows really the performance of different aspects
of our regional networks, collecting primarily seismic data.
We need administrative support, even more than normal, in the times
following an earthquake. And then the gray boxes in the right are the
kinds of scientific analyses typically we’re doing back in the office.
So, again, I’m happy to share this with anyone who would like to figure out
who they should be talking with to plan future response to earthquakes.
And then, last, this document, USGS Circular 1242, is a document
to guide our interactions with other NEHRP agencies,
and it was last written in 2003. You’ll be happy to know that there’s
a group of people actively writing the revision to this, and it will describe
the roles and responsibilities of the different NEHRP agencies.
So, with that, I’ll stop here and look forward to a lively discussion about
how we can all collaborate better on earthquake response. Thank you.