WEBVTT

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Regarded now.

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Good morning, if you're on the Pacific time zone, welcome back to our second session, which we are calling every Sunday at Brooded and Lay on the Floor, inconveniently close to the drawing room door.

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about Alquis peholazones, inconvenient fort locations, and liquefaction under cities and other places where it's not really helpful for them to be.

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So, a wonderful, wonderful moderator was for the session are going to be the

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excellent Tim Dawson and Keith Knudson, please take it away!

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Thanks for the introduction, Sarah. I hope we can be half as excellent as the prior set of

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moderators. Uh, that would be… that would please me. And for those of you who don't recognize the quote in the name of this session, both John and Sarah put links in the chat, so if you…

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Look in the chat, you can learn about why this session is named what it is.

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And the session is about, uh, primarily earthquake hazards with a little bit of a smattering at the end about…

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Um, how the city of Alameda is addressing some of these

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Uh, not, uh, well…

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liquefaction hazards, which is indeed an earthquake hazard, and the confluence of…

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Liquifaction hazard and rising sea levels, which a lot of people are talking about around the

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Bay margins. We have

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four speakers, all of whom are… each of whom are well-known to the…

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Bay Area Geologic community, and we're going to first hear from Austin Elliott, who's affiliate… I guess he's a large… no, a geologist at large.

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So, welcome, Austin. Thanks for being willing to talk with us.

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Good morning, everyone. Ora guten Abend from here in Berlin, Germany.

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Today, I'll talk about my work uncovering and updating what we know about one of the Bay Area's major urban faults.

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This work was conducted at the USGS in cooperation with the California Geological Survey, which is in charge of state fault zoning.

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This particular fault, named for the city that it runs through, is one of five major fault systems in the Bay Area Plate Boundary.

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It's a 20 kilometer long section at the southern end of a 400 kilometer structure that…

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includes the Green Valley and Bartlett Springs Faults to the north.

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At this latitude, it's the easternmost major strike-slip strand,

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But its relation to adjacent structures, including the calaveras and Greenville Fault to the south,

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remains somewhat ambiguous.

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Because of this potential connectivity with other stars, the National Seismic Hazard Model calculations suggest it has about a 16%

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probability of a man who did 6.7 or greater earthquake in a 3-decade window.

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exactly what sort of earthquake potential it has is complicated by the complex fault network,

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and a lack of information. Keeping your eyes on the figure at the far right, let me show you where geologic slip rates are.

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have been published.

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This map of published slip rates, compiled by Alex Hayden for the National Seismic Hazard Model

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update shows how relatively sparse observed long-term slip rates are, with tens to hundreds of kilometers in between.

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Which is easily enough to hide sizable and damaging ruptures, like, for example, the South Napa earthquake.

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2014.

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Uh, this, uh, complexity of the fault network and the relative dearth of

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observation points around it, uh, lead to a bunch of outstanding questions.

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how much can rupture lengths vary along the fault system?

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There are many different branch points, bends, and steps in the system where slip rates will sort of, uh, as kinematically required, need to change or vary along the strike of

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the faults. Um, so for these reasons, the plate boundary slip budget

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Distribution is not really precisely known along the length of each of these faults.

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Um, the Quaternity fault slip rates, as you see in this map, are only known at a handful of sites.

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Fault interactions may be quite complex,

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And, significantly, the seismic potential of any one of these faults depends on the fraction of aseismic slip.

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This last point is important because most of the faults within this system are known to slip away seismically.

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The region hosts some rather famous creep locales on the San Andreas, the Calaveras, and the Hayward Faults.

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And widespread regional monitoring has been conducted for decades.

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This map shows the statewide compilation of creep rates incorporated into the National Seismic Hazard Model.

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Among the salient knowledge about creep to date…

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We know that all major faults in the Bay Area exhibit creep at some level.

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We know that creep rates vary, uh, along the faults.

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It is increasingly observed that creep occurs in episodes or events.

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Not necessarily as a rule, but it's a quite common phenomenon the more data that we have.

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Uh, inner seismic creep, uh, in between Earthquakes is, of course, associated also with

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post-seismic creep in the immediate aftermath of an earthquake, which has implications for resiliency, rebuilding, recovery, all these things.

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Um, through all these new observations we have of how much coop there is in the world,

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We've come up with a lot of possible mechanisms or triggers of creep, but none of them yet appear universal, so there's a lot more study to be done.

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These results, about the creep rate around the entire state's fault system,

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are possible because of over half a century of monitoring and measurement.

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Since the 1960s, a seismically accumulating slip…

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Which is what we call fault creep.

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has been measured by surveys of local monuments spanning around 100 meter scales across fault systems.

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Across the vaults within the system.

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The collection of monument Arrays has been steadily expanded and monitored at least annually.

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since that time.

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More recently, remote geodetic imaging techniques have also continued to a fuller picture of interseismic ground velocity distributions and strain accumulation.

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These provide a compelling picture, but they also contain more noise and interference than well-sighted survey monuments.

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Recent projects employing low-altitude synthetic aperture radar instruments.

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flown on planes, essentially.

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uncrewed vehicles.

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have provided even greater spatial detail that helps resolve patterns in ground deformation.

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A few years ago, at this very meeting, Eric Fielding presented this image from that project.

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And the discontinuity at the Concord Fault, which I was beginning to study at the time,

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caught my eye.

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We zoom in to see a clear velocity discontinuity right along the trace of the fault.

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Or do we? When we look closely, uh, it emerges that the discontinuity is not

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co-located with the conventionally mapped

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ternary active fault trace.

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Uh, which inspired me to take a renewed look at the near-field fault zone.

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I'll take a moment here to explain what is known about the activity of the Concord Fault.

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Uh, it was neotectonically mapped in 1973, um, as essentially, uh, the effort around Eloquas Priolo fault zoning, because this was in an urban area.

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The northern half of the fault has been observed to creep. Uh, that's where downtown Concord is, and it's a bit of an older city, so Creep had already manifested in the urban environment.

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The southern half of the fault was inferred along the topographic

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break at the edge of the city with Lime Ridge.

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development and consulting trenches, uh, inferred the fault there, but did not conclude

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exclusively, positively identify the fault.

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in its, sort of, southern half.

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Given the mismatch between the UAV-SAR velocity discontinuity and the definitive quaternary fault mapping,

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I decided to go investigate, so I hopped on BART and took my bike out to Concord, where I conducted street-by-street reconnaissance,

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to inspect what we were seeing in the remote sensing imagery.

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Sure enough, I began to see exactly where I expected, uh, these little cracks and deflections in the curb lines.

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on every single street.

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So, I'll flip through a set of examples that demonstrate how each street that I visited

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Well, 28 out of 30 that crossed the fault at a high angle in its southern half.

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Uh, exhibited small right lateral offset or otherators of…

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strike slip folding. Um…

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pretty much exactly where the UAV SAR results indicated this discontinuity.

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Rather, as suspected, but over time, these tiny little curb offsets, as I went street by street, um, with

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more and more data gathering here, my confidence grew.

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that this was, in fact, the result of tectonic strike-slip faulting.

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Uh, here, just further examples, exhibiting the top…

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type of evidence that we see. Here, there are on echelon cracks in the asphalt in the street.

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The curb is deflected, and it's actually ponding water.

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Um, and then there's this disturbance in the bricks.

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These two streets, again, this is all very subtle, but you can see with foreshortening,

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the right lateral deflection of the curbs, just in front of the car on the left,

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And just at about the side of the car, on the right.

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Uh, in many cases, both sides of the streets exhibit, uh, these deflections.

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lending confidence that you're seeing something that's sort of a large-scale tectonic feature, rather than just

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Tree roots, or the settlement and whatever else is happening with sidewalks.

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Yet again, uh, examples of the deflections.

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Here in this instance on the right, there's actually a small bit of vertical deformation associated with it as well that's leading to this water being ponded against some little…

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zone of uplift, and maybe a corresponding zone of sustenance.

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Uh, like we see in natural mole tracks.

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Here, on the left, you can see, again, the deflection, backed by the garbage cans, um…

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Uh, it's, uh…

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In many cases, uh, there were discrete right lateral offsets that were measurable on the ground.

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However, they, uh, although they're high… at high angles to the fault, there was an obliquity that needed to be accounted for.

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And a further thing that we noticed was the long…

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the wider aperture of some of these

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deflections, so…

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The curbs were offset to the right, but over, uh, several, maybe even tens of meters distance,

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And so that required something a little more sophisticated than just measuring tapes.

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At the end of that reconnaissance, this is the map of locations where right lateral offsets and deflections of urban features were visible.

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You can see that they form a nice linear feature, parallel to, but up to half a kilometer away from the existing quaternary fault trace in orange.

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The black outline indicates the Algaspriolo Fault Special Studies Zone,

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Illustrating that updates are needed to account for this demonstrably active strand.

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In total, this newly mapped fault strand is 7 kilometers long, and entirely beneath the built-up area of suburban Concord and Walnut Creek.

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We were able to go further than just mapping the fault here.

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By surveying the offset features with high precision, we can measure the accumulated displacement at each street.

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On the right, you see our surveys of deflected curbs in map view, rotated into curb parallel coordinates and exaggerated in the orthogonal direction to illustrate the deflections.

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We used these measurements and trigonometry with the local fault trace orientation,

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To calculate magnitudes of offset along strike.

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Which range from 8 to 20 centimeters.

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The variability appeared to roughly correlate with street and housing tract age.

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Which means that we can go even a step further and use feature ages to estimate slip,

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creep rates. Danielle Madugo and I looked into county assessor parcel data to determine the ages of the subdivision tracts, assuming that these represent the ages when the curbs were originally installed.

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Most in this area date from the late 1970s and 80s.

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We put the values of subdivision age and offset magnitude together in the plots here.

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On the left, you see measured deflection versus maximum feature age.

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And see that all fall within a range representing 2 to 3 millimeters per year slip rate.

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If any sidewalks had been replaced, the observed offsets would have accumulated over less time,

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And thus represented higher rates.

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As we see in… so these rates represent minimum.

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As we see in the spatial view on the right,

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The rates we obtain, uh, using this method are relatively consistent with the precisely measured creep rates at alignment arrays to the north in downtown.

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And show no obvious spatial trend.

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To sum up, the active trace of the Conger Fault is not where it was previously inferred.

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But instead, 100 meters to 500 meters to the west,

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out in the built-up suburban subdivisions of Concord and Walnut Creek.

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Uh, the whole length of the fault is creeping, not just its northern portion.

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Uh, and the entire fault may undergo creep episodes. Uh, we know this to be the case where the alignment arrays are in the north.

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And we had anecdotal evidence from homeowners about, uh,

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the occasions of utility repairs.

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that suggests that perhaps in the South, the fault is also creeping episodically.

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Uh, there's further evidence from, uh…

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Katrina Timofieva, who looked at, um, INSAR…

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Results, and showed…

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creep events occurring across the whole fault zone. So, more study and observation is going to be needed in order to determine

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whether this is really happening in the South,

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And whether it happens consistently with

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the slip events…

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observed in the north.

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In downtown Concord, the fault has been observed.

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using alignment arrays, surveyed annually or subannually since 1979.

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You can see the results from those of accumulated slip over time in the plot to the right.

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Uh, these represent two different stations, and the accumulating slip. You can see that there's a…

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Of course, a long-term average rate of around 3…

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millimeters per year.

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Uh, it's actually… what it actually is comprised of is these little episodes of something around

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a centimeter, uh, every 3 point…

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8 years.

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Um, and then in between this lower rate of about a millimeter per year.

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So, the question is, is this same thing happening in the South? And we'll need more observations to determine that.

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finally, I'd like to wrap up by pointing out that, uh, this… if you would like more information,

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This work has been published in SRL last year.

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Uh, you can look at that paper for more details, maps, uh, detailed data sets showing where the offsets are.

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And the calculations that we've made.

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Uh, of course, for really robust creep measurements and ongoing monitoring, more work is going to need to be done.

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The California Geological Survey has already incorporated these results into the AP Fault Zone Review,

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And preliminary revision of the polygons is due to be released in May.

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Uh, you can contact Danielle Madugo or Judy Zachariason for more information on this.

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Uh, further questions that I was saying about this vault are, of course, how does creep vary in time?

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Uh, is it the same in the South as in the North? Does…

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pre-propagate along the fault? What are the duration of these episodes?

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Um, understanding whether two active traces actually exist at this latitude,

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And why are they partitioning slip? Is there a difference in frictional behavior? Has there been an evolution from one to the other?

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Uh, and then the outstanding question of

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Continuity and connectivity southward. Is there a right step, a left step? Is there both?

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How is creep transferred through this whole fault system?

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Thank you for your time.

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Right. Thank you, Austin, for that amazing talk.

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Um, just a reminder, we have a very active chat going on, so if you have questions, please put them in the chat, we'll get back to them if they're not answered.

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transparent. We, like, you know, this is a session about active faults, and we like to have an active…

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chat session going on as well.

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Um, for those of you who don't know me, I'm Tim Dawson, I'm at CGS as the program manager for Seismic Hazards, and it's my honor to, um, introduce the next speaker.

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And that will be Robert Sickler, who will be speaking about seismic imaging of wrench front

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faults on the San Francisco Peninsula in the city of San Carlos, a city that I've lived in.

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So, please…

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Press play, thank you.

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Hello and welcome. I am going to speak to you about a seismic imaging campaign conducted for the purpose of identifying buried traces of the Foothills Fault System.

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which runs along the eastern edge of the San Francisco Peninsula.

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This project was conducted in the central part of the city of San Carlos.

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So let's now look at an overview map to get us started.

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Alright, let's look at this inset map up here. Here's the state of California, San Francisco.

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the greater San Francisco Bay Area, showing the cities of San Francisco, San Jose, Palo Alto, San Carlos,

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This box here is, of course, the outline of this larger map.

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Here is the San Andreas Fault.

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very well mapped Holocene Active Seraphalt.

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The range front faults in the south, mostly hidden by alluvium. The city of San Carlos, outlined in blue.

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And this big red oval, where you notice there are no range front…

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faults mapped SAFER1, which I will get to later.

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And now let's go look at a close-up map of the field area.

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Alright, here is our topographic map of the city of San Carlos.

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Here are the streets of El Camino Real and Alameda de las Pulgas, for those familiar with the area geography.

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Here we conducted a high-resolution seismic imaging campaign along three suburban streets, as shown by these black outlines.

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along Eucalyptus Avenue, Howard Avenue, and Graceland.

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The eucalyptus Avenue did not have any seismic signal-absorbing underground utilities, which made it an excellent testbed for our methods.

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And please note this combined topographic high and bedrock knob

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Which will become important later.

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So let's look at some notes on the project's logistics next.

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Alright, for data acquisition, we deployed several hundred smart solo brand three-component standalone seismometers called nodes at the edge of the pavement along the three streets.

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The nodes and co-located seismic energy inputs for space to every 5 meters.

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Seismic energy was generated by several means. P waves were generated by multiple hits from a modified paving breaker machine striking an aluminum plate.

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S waves were generated by two methods.

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depending on… upon field conditions,

00:19:43.000 --> 00:19:48.000
Either an aluminum block weighted down by a person who was struck with a sledgehammer,

00:19:48.000 --> 00:19:56.000
or a hydraulically lifted ram was impulsively fired against a 45-degree angled block pinned to the pavement.

00:19:56.000 --> 00:19:59.000
From these data, we created VP, VS,

00:19:59.000 --> 00:20:07.000
BPVS and Poisson's ratio models and reflection profiles, which we will see next.

00:20:07.000 --> 00:20:12.000
Alright, here's a seismic profile of the eucalyptus P wave tomography.

00:20:12.000 --> 00:20:19.000
Uh, keep in mind, in all the profiles that we shall see, uh, that the depth is relative to sea level,

00:20:19.000 --> 00:20:22.000
Uh, cross streets are usually labeled

00:20:22.000 --> 00:20:31.000
The white contour line is the 1500 meter per second contour line, which we find from all our studies to be coincident with the top of the water table.

00:20:31.000 --> 00:20:34.000
So here in the P wave, here is the velocity

00:20:34.000 --> 00:20:38.000
scale, and in this particular model,

00:20:38.000 --> 00:20:45.000
Uh, we have velocities going from about 1,200 meters per second near the second to close to 4,000 at the bottom.

00:20:45.000 --> 00:20:49.000
Oh, and the inflection in the 1500 meter per second

00:20:49.000 --> 00:20:54.000
line is likely some sort of groundwater disruption. We find that quite common.

00:20:54.000 --> 00:21:00.000
Anyway, the main takeaway here is this big, of course, VP high in the middle of the model.

00:21:00.000 --> 00:21:06.000
And we find, from decades of work in the San Francisco Bay Area and Franciscan rocks, that

00:21:06.000 --> 00:21:11.000
a VP of greater than about 2,800 meters per second, so that means all this stuff.

00:21:11.000 --> 00:21:15.000
is some kind of Franciscan bedrock.

00:21:15.000 --> 00:21:20.000
Alright, let's move on to the next one.

00:21:20.000 --> 00:21:28.000
Alright, here's our Eucalyptus Avenue VS model. It's derived from the multi-channel analysis of surface waves.

00:21:28.000 --> 00:21:38.000
And the model ranges from about 200 meters per second at the surface to around 1600 meters per second at about 70 meters depth.

00:21:38.000 --> 00:21:47.000
There are some lateral changes in VS, one at about meter 80, and this very prominent one at around meter…

00:21:47.000 --> 00:21:54.000
260. And this one, especially at 260, we see is consistent for faulted, fractured

00:21:54.000 --> 00:21:56.000
uh, Franciscan rock.

00:21:56.000 --> 00:22:01.000
Alright, let's look at the next one.

00:22:01.000 --> 00:22:05.000
Here is the eucalyptus Avenue VPVS ratio model.

00:22:05.000 --> 00:22:11.000
VPVS ratios along the seismic profile range from about 2.5 to about 6.5.

00:22:11.000 --> 00:22:13.000
Unusually high ratios,

00:22:13.000 --> 00:22:18.000
greater than 5 are seen near the surface between about distance meters 40 and 120,

00:22:18.000 --> 00:22:24.000
And between distance meters 150 and 250, which are at about a depth of 20 to 30 meters.

00:22:24.000 --> 00:22:31.000
What does this mean, you ask? Well, as we have found in other Bay Area sites, many of them verified by fault trenching,

00:22:31.000 --> 00:22:35.000
High VPVS ratios often correspond to saturated fault zones.

00:22:35.000 --> 00:22:42.000
Therefore, the nerve surface extended zone of high VPVS ratios likely correlate with subsurface zones of ponded

00:22:42.000 --> 00:22:45.000
Water-saturated, unconsolidated sediments.

00:22:45.000 --> 00:22:50.000
The deeper extended zone of high VP-VS ratios between meters 150

00:22:50.000 --> 00:22:57.000
And 250 likely correlate with faulted rocks. So let's look at another model.

00:22:57.000 --> 00:23:00.000
Alright, here's the eucalyptus Avenue-Poisson's ratio model.

00:23:00.000 --> 00:23:03.000
Poisson's ratio relates to the presence or absence of fluids.

00:23:03.000 --> 00:23:08.000
In this model, Poisson's ratios range from about 0.4 to about .48.

00:23:08.000 --> 00:23:11.000
the profile in the upper 60 meters.

00:23:11.000 --> 00:23:14.000
Because fully saturated sediments typically have values around

00:23:14.000 --> 00:23:18.000
for 3, and Pure Fluid has a Poisson's ratio of 0.5.

00:23:18.000 --> 00:23:24.000
We suggest that the zones of height, Poissons ratios correlate with water-saturated zones in the subsurface.

00:23:24.000 --> 00:23:28.000
Broadwater generally flows from downslope, southwest.

00:23:28.000 --> 00:23:30.000
Northeast, or left to right in these images.

00:23:30.000 --> 00:23:33.000
And maybe impeded near barriers.

00:23:33.000 --> 00:23:35.000
My barriers are just meters of 125, and 2.

00:23:35.000 --> 00:23:44.000
60. These groundwater flow disruptions may mean that falls extend very close to the ground surface, say less than…

00:23:44.000 --> 00:23:49.000
So we have water-saturated near-surface sediments between zero…

00:23:49.000 --> 00:23:52.000
Major 125.

00:23:52.000 --> 00:23:57.000
And water-saturated and faulted, probably Franciscan rock between

00:23:57.000 --> 00:24:03.000
260. So let's put all of this information together.

00:24:03.000 --> 00:24:11.000
Alright, this is our combined model of the migrated reflection image with the VP model superimposed along Eucalyptus Avenue.

00:24:11.000 --> 00:24:17.000
The migrated reflection image shows collapsed fractions and vertically offset layers.

00:24:17.000 --> 00:24:23.000
Uh, which show a fault zone between meters 120 and 300. And some of

00:24:23.000 --> 00:24:27.000
But not all of the possible vault traces are shown by the red lines.

00:24:27.000 --> 00:24:32.000
The other models and this combined model suggest that water is being ponded in the alluvial mountainfront.

00:24:32.000 --> 00:24:38.000
apron between the higher bedrock to the west and the San Francisco Bay to the east. See the elevation profile.

00:24:38.000 --> 00:24:43.000
by near-surface faulting. So, do you remember that bedrock knob from the field map area?

00:24:43.000 --> 00:24:49.000
Let's go back and take a look at it with an important addition added.

00:24:49.000 --> 00:24:51.000
And here's our map again of…

00:24:51.000 --> 00:24:56.000
San Carlos, and remember that topographic high?

00:24:56.000 --> 00:24:59.000
And bedrock knob down here.

00:24:59.000 --> 00:25:06.000
Guess what's been mapped has been right through there? Oh, it's the Belmont Hill fault! Hey, hooray!

00:25:06.000 --> 00:25:14.000
So, uh, it's mapped as, uh, Franciscan bedrock. Oh, there's a surprise. Bisected by the Belmont Fault.

00:25:14.000 --> 00:25:20.000
Hey, it looks like our techniques work. Well, we've been doing this stuff for many years,

00:25:20.000 --> 00:25:23.000
And we have high confidence in our work,

00:25:23.000 --> 00:25:29.000
And so, this isn't really a surprise to us, but it's great to have this wonderful ground trut thing to show that

00:25:29.000 --> 00:25:34.000
you know, we still got it. So let's look at some more eye candy on some of these additional, uh…

00:25:34.000 --> 00:25:38.000
profile areas.

00:25:38.000 --> 00:25:46.000
Alright, here is our Howard Avenue VP model, the P-wave velocities range from about 1500 meters near the surface.

00:25:46.000 --> 00:25:48.000
Hmm, remember that value?

00:25:48.000 --> 00:25:53.000
to around 4,000 meters per second at around 50 to 75 meters below the ground surface.

00:25:53.000 --> 00:25:58.000
At 1,500 meter per second contour, which is usually the top of groundwater.

00:25:58.000 --> 00:26:00.000
is very close to the surface.

00:26:00.000 --> 00:26:05.000
A prominent high velocity, that is about 3,000 meters per second structure

00:26:05.000 --> 00:26:13.000
are present both between meters 200 and 450, and between meters 900 and 1400.

00:26:13.000 --> 00:26:19.000
We interpret most of the subsurface higher velocity material, that is, VP greater than around 3,000 meters per second,

00:26:19.000 --> 00:26:24.000
along this profile to consist with Franciscan rock.

00:26:24.000 --> 00:26:29.000
And bounding these relatively high zones are relatively low velocity zones between meters.

00:26:29.000 --> 00:26:32.000
60 and 200.

00:26:32.000 --> 00:26:35.000
500 and 625.

00:26:35.000 --> 00:26:37.000
And 800 and 850…

00:26:37.000 --> 00:26:42.000
1,050 and 1150, and 1,300 and 1500.

00:26:42.000 --> 00:26:45.000
excuse me, 1300 and 1350.

00:26:45.000 --> 00:26:50.000
And we interpret these lower velocity zones as potential zones of faulting.

00:26:50.000 --> 00:26:52.000
So let's look at the shear wave.

00:26:52.000 --> 00:26:57.000
profile for some more information on shearing.

00:26:57.000 --> 00:27:03.000
Here is the Howard Avenue shearwave model. VS ranges from around 200 meters per second.

00:27:03.000 --> 00:27:08.000
near the surface to about 1200 meters per second at about 80 meters depth.

00:27:08.000 --> 00:27:14.000
We interpret most of the subsurface material with VS greater than about 750 meters per second.

00:27:14.000 --> 00:27:16.000
to be Franciscan bedrock.

00:27:16.000 --> 00:27:21.000
Near-surface zones of reduced VS occur between meters 60 to 200, 500,

00:27:21.000 --> 00:27:24.000
625 and 800 and 850.

00:27:24.000 --> 00:27:27.000
We find these zones are often associated with faults.

00:27:27.000 --> 00:27:34.000
Some of these changes in VS become more pronounced near the base of the model, such as those between meters 300 to 400.

00:27:34.000 --> 00:27:38.000
1,000, 2,050, and 1,250 to 1350.

00:27:38.000 --> 00:27:41.000
Suggesting even greater reductions in VS at depth.

00:27:41.000 --> 00:27:45.000
So shearing during faulting faulting causes large reductions in VS.

00:27:45.000 --> 00:27:51.000
As a result, faulted and saturated rocks typically have unusually high VPVS ratios.

00:27:51.000 --> 00:27:53.000
So let us look at a VPVAS.

00:27:53.000 --> 00:27:57.000
model next.

00:27:57.000 --> 00:28:00.000
Alright, here is the Howard Avenue VPVS model.

00:28:00.000 --> 00:28:07.000
Unusually high VP ratios greater than 5 are seen near the surface between meters 0 and 75, and between

00:28:07.000 --> 00:28:09.000
meters 200 and 500.

00:28:09.000 --> 00:28:12.000
Uh, at about 20 meters depth.

00:28:12.000 --> 00:28:21.000
Southwest of meter 75, the ground surface slopes slightly southwest towards a swale. This area may represent a package of saturated sediment that thickens westward.

00:28:21.000 --> 00:28:34.000
an area of low VPVS ratios between meters 75 and 200 has higher VS and lower VP relative to the adjacent areas, suggesting an abrupt change in material composition or reduced saturation.

00:28:34.000 --> 00:28:36.000
This zone is also near the mountainfront.

00:28:36.000 --> 00:28:43.000
So we interpret this area as consisting of unsaturated bedrock near the surface and at deeper levels.

00:28:43.000 --> 00:28:49.000
Again, as seen in other locations in the Bay Area, high VPVS ratios are seen as saturated fault zones.

00:28:49.000 --> 00:28:52.000
east of meter 625.

00:28:52.000 --> 00:28:58.000
unusually high VPVS ratios extend from near the surface to about 50 meters in depth.

00:28:58.000 --> 00:29:02.000
At several locations, the high VP-VS ratios

00:29:02.000 --> 00:29:04.000
abruptly stopped downslope.

00:29:04.000 --> 00:29:10.000
Like, near meter 625 and 850, and likely result from disruptions of downed water.

00:29:10.000 --> 00:29:12.000
Downslope groundwater flow.

00:29:12.000 --> 00:29:18.000
These disruptions may mean that faults extend very close to the ground surface, probably less than 10 meters deep.

00:29:18.000 --> 00:29:30.000
The near surface extended zones of high PVS ratios east of meter 625 likely represent subsurface zones of ponded, water-saturated, unconsolidated sediments in the upper 25 meters of the profile.

00:29:30.000 --> 00:29:32.000
However, the deeper extended

00:29:32.000 --> 00:29:35.000
Zones of high VPVS ratios, like result.

00:29:35.000 --> 00:29:41.000
result from faulting within Bedrock. So let's move on.

00:29:41.000 --> 00:29:47.000
Alright, here's the combined migrated reflection image and VPVS model for Howard Avenue.

00:29:47.000 --> 00:29:51.000
Please note the topographic profile with topographic inflection points.

00:29:51.000 --> 00:30:00.000
The migrated image shows collapsed diffractions and vertically offset layering, which is indicative of faulting, centered in zones between meters 60 to 200,

00:30:00.000 --> 00:30:03.000
500 to 625.

00:30:03.000 --> 00:30:09.000
800 to $850, 1,050 to 1150, and 1,300… 1350.

00:30:09.000 --> 00:30:15.000
Some, but not all, fault traces are shown as near vertical red lines.

00:30:15.000 --> 00:30:19.000
The unsaturated bedrock is shown by the dark blue to teal colors.

00:30:19.000 --> 00:30:25.000
Overlying the bedrock is an eastward thickening mantle of layered sediments in the light green to red colors.

00:30:25.000 --> 00:30:32.000
As seen at other locations in the Bay Area, high VP-VS ratios are seen in saturated fault zones.

00:30:32.000 --> 00:30:37.000
east of meter 625, unusually high VPVS

00:30:37.000 --> 00:30:41.000
Ratios extend from near the surface to about a 50 meter depth.

00:30:41.000 --> 00:30:46.000
At several locations, the high VPVS zones abruptly stop downslope.

00:30:46.000 --> 00:30:49.000
C areas need major 625 and 850.

00:30:49.000 --> 00:30:53.000
And likely result from disruptions of downslope groundwater flow.

00:30:53.000 --> 00:31:01.000
The near-surface disruptions in the high VPVS zones may mean that the faults extend very close to the ground surface, that is, less than 10 meters depth.

00:31:01.000 --> 00:31:05.000
So let us continue.

00:31:05.000 --> 00:31:10.000
I'll briefly show this combined VPVS model and reflection image for Graceland Avenue.

00:31:10.000 --> 00:31:13.000
Once again, we find shallow faulting.

00:31:13.000 --> 00:31:19.000
So what do all these San Carlos profiles mean for the big picture?

00:31:19.000 --> 00:31:22.000
So, we have located the frontal fault system.

00:31:22.000 --> 00:31:28.000
Which is likely extension of the Pulgus Fault coming in from the south, as well as the Serra Fault coming in from the north.

00:31:28.000 --> 00:31:31.000
We found a trace of the Belmont Hill Fault,

00:31:31.000 --> 00:31:38.000
And what is probably an extension of the Stanford Fault in the city of San Carlos.

00:31:38.000 --> 00:31:43.000
And finally, this work would have been impossible without the help of other USGS employees,

00:31:43.000 --> 00:32:04.000
Student interns and volunteers. Thank you folks so, so much for all you did for us.

00:32:04.000 --> 00:32:11.000
Thank you, Robert, that was awesome, and you're getting lots of, uh, applause, or virtual applause.

00:32:11.000 --> 00:32:18.000
Um, and there's a lively discussion going on in the chat, so for those of you who don't have your chat turned on, I suggest you do that.

00:32:18.000 --> 00:32:20.000
Our next speaker is…

00:32:20.000 --> 00:32:26.000
Judy Zachariason from CGS, and she's going to tell us a little bit about, um,

00:32:26.000 --> 00:32:31.000
the QFAL database, how that's working, and its relationship to the…

00:32:31.000 --> 00:32:33.000
AP zones.

00:32:33.000 --> 00:32:47.000
Take it away, Judy.

00:32:47.000 --> 00:32:49.000
We've all seen this, I'm sure.

00:32:49.000 --> 00:32:54.000
Along with how utterly cool to have captured that on video, one of my first thoughts when I saw it was…

00:32:54.000 --> 00:32:58.000
Well, I bet they're thankful that wasn't 50 feet to my left.

00:32:58.000 --> 00:33:01.000
Because where faults are located matters.

00:33:01.000 --> 00:33:04.000
If your house is on the fault that ruptures.

00:33:04.000 --> 00:33:08.000
or not, can be the difference between this…

00:33:08.000 --> 00:33:12.000
And this.

00:33:12.000 --> 00:33:20.000
And Judy Zacharias, and I'm the supervisor of the Fault Zoning Unit within the Seismic Hazards Program at the California Geological Survey.

00:33:20.000 --> 00:33:30.000
The other geologists in our group include Carla Rosa, Danielle Madugo, Gordon Seitz, Mike DeFrisco, and Tyler Ledinsky, two of whom have given thunder talks that you've already heard.

00:33:30.000 --> 00:33:42.000
Bell Filibosian asked me if I would speak to the workshop about the group, specifically what our process is for adding, modifying, and removing faults from two fault databases that we develop and maintain.

00:33:42.000 --> 00:33:48.000
The Alquispriolo Earthquake fault zones, and the California Quaternary Fault Database.

00:33:48.000 --> 00:33:59.000
This annual workshop has a diverse audience of people from all walks of life for whom earthquakes and earthquake hazard matter, and I want to target this talk toward that diverse audience. So it's not going to be a technical talk,

00:33:59.000 --> 00:34:05.000
But rather, it will just be generally explanatory about what these datasets are, how they differ, and of course,

00:34:05.000 --> 00:34:10.000
How changes are implemented as requested.

00:34:10.000 --> 00:34:19.000
The question is, how are faults added to and removed from the quaternary fault database in Alquaolosomes? And in short, the answer is CGS,

00:34:19.000 --> 00:34:23.000
makes and revises earthquake fault zones in the AP program.

00:34:23.000 --> 00:34:31.000
Centered on likely Holocene faults using topographic data, existing mapping, and site-specific fault investigations.

00:34:31.000 --> 00:34:42.000
And the quaternary fault database, CGS evaluates and compiles published and unpublished mapping of quaternary faults produced and provided by investigators in the earthquake

00:34:42.000 --> 00:34:52.000
community, and we consider factors such as resolution, age scale, data sources, publication status, and regional applicability in deciding whether to include those.

00:34:52.000 --> 00:34:57.000
Yeah. So, we're done. That's the answer.

00:34:57.000 --> 00:35:00.000
But I guess I'll give you a little more.

00:35:00.000 --> 00:35:03.000
information than that.

00:35:03.000 --> 00:35:19.000
These are descriptions of the basis for the two datasets. The Alclus Priolo Earthquake Fault Zoning Act is meant to prevent structures for human occupancy being built over the traces of active faults that reach the ground surface to mitigate against collapse and catastrophic damage from surface rupture.

00:35:19.000 --> 00:35:24.000
The Q-Faults database, by contrast, is to provide information about quaternary faults.

00:35:24.000 --> 00:35:27.000
information for whatever purpose the user wants.

00:35:27.000 --> 00:35:37.000
First, the AP side of things. The AP Act requires that the state geologist, or CGS, develop zones around faults that are sufficiently active and well-defined.

00:35:37.000 --> 00:35:39.000
fuzzy term, if ever there was one.

00:35:39.000 --> 00:35:43.000
According to Special Publication 42,

00:35:43.000 --> 00:35:49.000
Sufficiently active means there is evidence of Holocene surface displacement along one or more of its segments or branches.

00:35:49.000 --> 00:35:55.000
And well-defined means its trace is clearly detectable by a trained geologist as a physical feature

00:35:55.000 --> 00:35:58.000
at or just below the ground surface.

00:35:58.000 --> 00:36:04.000
Development within an earthquake fault zone then requires a site-specific investigation prior to construction.

00:36:04.000 --> 00:36:10.000
To ensure no structures for human occupancy overlie active traces.

00:36:10.000 --> 00:36:17.000
Prioritizing which faults to zone or rezone first depends on a variety of criteria, including significance of the fault.

00:36:17.000 --> 00:36:25.000
rate, displacement, etc. Location, is it in urbanized or urbanizing area? Does it cross major lifelines?

00:36:25.000 --> 00:36:30.000
Practicality, do we have the data? Can we actually map the fault?

00:36:30.000 --> 00:36:37.000
In recent years, we've been focused on re-evaluating some of the high-hazard faults, such as the San Andreas-Hayward-Rogers Creek,

00:36:37.000 --> 00:36:42.000
As some sections of these fault zones are still the original zones defined in the 70s.

00:36:42.000 --> 00:36:50.000
But we are also evaluating currently unzoned vaults, where development is moving along. For example, the Bennett Valley Fault is in the works.

00:36:50.000 --> 00:36:55.000
The reason for evaluating currently unzoned faults for zoning in the first place seems obvious,

00:36:55.000 --> 00:37:02.000
The new Holocene Act defaults is identified, it needs to be evaluated, and a zone established if there is any chance of future development.

00:37:02.000 --> 00:37:05.000
The basis for re-evaluating or rezoning.

00:37:05.000 --> 00:37:08.000
is often because new and better data are available.

00:37:08.000 --> 00:37:13.000
New traces have been identified by the community, or someone in the user community has contacted us

00:37:13.000 --> 00:37:18.000
And provided a compelling argument for why a fault should be re-evaluated.

00:37:18.000 --> 00:37:28.000
In the first iteration of zoning, after the AP Act was passed, California Division of Mines and Geology just slapped zones around existing map traces of the major faults.

00:37:28.000 --> 00:37:34.000
Then faults were evaluated more carefully, using geomorphology found on topographic maps and aerial photographs.

00:37:34.000 --> 00:37:41.000
Now, we have LiDAR, INSAR GIS, new data, and new tools that allow us to do a still better job.

00:37:41.000 --> 00:37:45.000
And this drives some of our re-evaluation decisions.

00:37:45.000 --> 00:37:50.000
In this slide, I'll go over the AP zoning process. It's pretty straightforward.

00:37:50.000 --> 00:37:52.000
We use topographic data,

00:37:52.000 --> 00:37:59.000
imagery, existing mapping, and localized site investigations to identify likely Holocene fault traces.

00:37:59.000 --> 00:38:06.000
In the top panel, you can see multiple colored traces reflecting different people's previous mapping.

00:38:06.000 --> 00:38:08.000
And colored polygons.

00:38:08.000 --> 00:38:12.000
showing site investigations that either found or didn't find a fault.

00:38:12.000 --> 00:38:15.000
In the second panel,

00:38:15.000 --> 00:38:19.000
You see the zoner's fault mapping using these kinds of data sources.

00:38:19.000 --> 00:38:25.000
Showing fault traces and point geomorphic features, these little dots here.

00:38:25.000 --> 00:38:30.000
or fault exposures identified in the data.

00:38:30.000 --> 00:38:37.000
Once we've completed the mapping and identified those faults we consider sufficiently active and well-defined, we create zones around them.

00:38:37.000 --> 00:38:44.000
Using a default buffer of 500 feet on either side, which you can see in the bottom panel here.

00:38:44.000 --> 00:38:52.000
Although we may, and generally do, do our mapping at larger scales, we present the official maps at a scale of 1 to 24,000.

00:38:52.000 --> 00:39:00.000
Once official, these zones are regulated for development, requiring fault investigations for projects subject to the Act.

00:39:00.000 --> 00:39:05.000
rezoning includes evaluating whether to retain faults defining existing zones.

00:39:05.000 --> 00:39:11.000
Since fault investigations are required for development within zones, and the reports must be provided to CGS,

00:39:11.000 --> 00:39:14.000
We often have, during a re-evaluation,

00:39:14.000 --> 00:39:17.000
More subsurface information than was available the first time around.

00:39:17.000 --> 00:39:24.000
And we may find sufficient information to conclude that a zone fault does not actually meet the criteria for zone…

00:39:24.000 --> 00:39:29.000
A recent example is the re-evaluation of the San Andreas and the Woodside area by Gordon Seitz.

00:39:29.000 --> 00:39:32.000
In which he chose to remove the zone around the Kenyatta Fault.

00:39:32.000 --> 00:39:36.000
Given that geomorphic expressions weaker than elsewhere.

00:39:36.000 --> 00:39:41.000
And in numerous fault investigations, none had identified a Holocene fault.

00:39:41.000 --> 00:39:47.000
You can see in the right panel, the gray previous zone and the yellow revised zone.

00:39:47.000 --> 00:39:58.000
The critical element here is that for AP mapping, it is CGS geologists that map the faults and make the zones. They use other people's data to help, but they are doing their own mapping.

00:39:58.000 --> 00:40:05.000
It's also important to clarify that it is the zones, not the fault traces, that have regulatory implications.

00:40:05.000 --> 00:40:10.000
The fault traces as we have mapped them and show them, are actually secondary.

00:40:10.000 --> 00:40:13.000
We show them only to explain why the zones are there.

00:40:13.000 --> 00:40:16.000
So don't get fixated on the details of the traces.

00:40:16.000 --> 00:40:22.000
AP's owners don't locate the vaults at the parcel level, that is the consulting geologist's job.

00:40:22.000 --> 00:40:27.000
There's no fault found where the AP traces, that's not a problem with the AP mapping.

00:40:27.000 --> 00:40:29.000
It's just lucky for your client, they can build.

00:40:29.000 --> 00:40:31.000
The act is done what it was meant.

00:40:31.000 --> 00:40:34.000
to do.

00:40:34.000 --> 00:40:39.000
Final piece of information to share regarding the AP database is its location.

00:40:39.000 --> 00:40:45.000
It is located in the CGS Information Warehouse at the EQ zap tile outlined in red.

00:40:45.000 --> 00:40:54.000
The figure here on the right just shows the fault zones for Clarity, but this page also has seismic hazard zones for earthquake-induced landslide and liquefaction hazard.

00:40:54.000 --> 00:41:04.000
From this page, you can access the maps and the fault evaluation reports for the zones. You can access the GIS files from the maps and Reports tile in yellow,

00:41:04.000 --> 00:41:10.000
Note that we're doing some revision of this page in the coming months, so it may look a little different if you go to it.

00:41:10.000 --> 00:41:12.000
I think that explains how…

00:41:12.000 --> 00:41:17.000
Faults for AP zones are added to, modified, and removed from that database.

00:41:17.000 --> 00:41:22.000
The process and the products are pretty well defined.

00:41:22.000 --> 00:41:25.000
By contrast, we come to the red-headed stepchild.

00:41:25.000 --> 00:41:27.000
Quaternary fault database.

00:41:27.000 --> 00:41:34.000
This used to be managed by USGS directly with the help from the states, but is now managed by the states and provided to USGS.

00:41:34.000 --> 00:41:42.000
The California Q-Faults database was last updated in 2017, and it is well past time to do so again.

00:41:42.000 --> 00:41:47.000
The process of building this database and the product is different from the AP mapping.

00:41:47.000 --> 00:41:52.000
Most significantly, CGS geologists don't do the mapping for Q faults.

00:41:52.000 --> 00:41:59.000
We compile existing mapping that has been produced by other practitioners for a multitude of purposes.

00:41:59.000 --> 00:42:03.000
Research, consulting, regional mapping, fault evaluations,

00:42:03.000 --> 00:42:07.000
As such, rather than being at least somewhat uniform, like the AP maps,

00:42:07.000 --> 00:42:13.000
Q Faults is a hodgepodge of different authors' purposes, scales, dates, quality.

00:42:13.000 --> 00:42:21.000
And Bill Bryant put it together, he used pretty much all the existing data he could find, published vault maps, CDMG, CGS unpublished mapping.

00:42:21.000 --> 00:42:28.000
Consulting reports, knee hurt maps, theses, bedrock geologic maps, with a few traces mapped through the yellow stuff.

00:42:28.000 --> 00:42:36.000
And in some cases, revising that mapping based on his own evaluation of other information, like air photos and LIDAR.

00:42:36.000 --> 00:42:41.000
It was an epic effort, and there are some 60,000 unique line segments in his database.

00:42:41.000 --> 00:42:46.000
Given this, the process for modifying the database is very different than AP.

00:42:46.000 --> 00:42:54.000
I say this to clarify that in the update process, we are not comprehensively going through the entire state and redoing Bill's original work.

00:42:54.000 --> 00:42:59.000
We don't have the time or resources, and it doesn't need it, I don't think.

00:42:59.000 --> 00:43:09.000
It currently may not check all the boxes people want, but it's still pretty good if we consider how it is used by most end users, which is as a starting point, not a final product.

00:43:09.000 --> 00:43:18.000
So our approach is to add faults or revise faults if new mapping becomes available that we think improves on the existing mapping.

00:43:18.000 --> 00:43:21.000
Due to being based on better data,

00:43:21.000 --> 00:43:25.000
LiDAR, better resolution, better age control,

00:43:25.000 --> 00:43:30.000
And that will be on a case-by-case basis, evaluated by CGS.

00:43:30.000 --> 00:43:37.000
We will begin hosting the database in the information warehouse later this year, fingers crossed.

00:43:37.000 --> 00:43:43.000
Because CGS is just the compiler, we need people to provide their mapping in order to incorporate it.

00:43:43.000 --> 00:43:56.000
We will re-evaluate faults people ask us to reevaluate. We don't comb through all the literature to find every new fault map. If you have mapped a fall and think your mapping is an improvement, please let us know, and we will take a look.

00:43:56.000 --> 00:44:02.000
Similarly, if you've discovered and mapped a new, i.e. not previously identified fault.

00:44:02.000 --> 00:44:09.000
finally, if you have reason to believe a fault in the database doesn't just need revision, but removal,

00:44:09.000 --> 00:44:17.000
You should provide us with an evaluation laying out the basis for unmapping something somebody else has reported having seen and mapped.

00:44:17.000 --> 00:44:24.000
All contributions add, revise, remove. You should be prepared to support with documentation and peer review.

00:44:24.000 --> 00:44:28.000
We've created an upload portal, which the link…

00:44:28.000 --> 00:44:32.000
And QR code, you can see here.

00:44:32.000 --> 00:44:37.000
To facilitate users providing mapping for our consideration. You can always contact me as well.

00:44:37.000 --> 00:44:45.000
To have your mapping considered, you must provide GIS files. We are not digitizing from your PDF or hard copy scan.

00:44:45.000 --> 00:44:48.000
and reference documentation. Copy of the paper, the…

00:44:48.000 --> 00:44:51.000
thesis, report, whatever.

00:44:51.000 --> 00:45:00.000
Further, these here, you can't really see them, are the main fields we have in the database, and as many of those as you can provide, the better.

00:45:00.000 --> 00:45:11.000
We are only including quaternary faults. If you've met Bedrock and quaternary faults, you should remove the pre-quaternary faults. We don't want them, and you're the one who knows which is which.

00:45:11.000 --> 00:45:14.000
And if you can provide age information,

00:45:14.000 --> 00:45:18.000
Within the quaternary category, even better.

00:45:18.000 --> 00:45:28.000
Your map should be appropriate for a regional statewide fault map, and we need actual faults, not just dribs and drabs of lineum and scarpwoods, etc.

00:45:28.000 --> 00:45:33.000
It's better if you interpolate between the observed features to give us an actual fault trace.

00:45:33.000 --> 00:45:37.000
Keep the scale appropriate to a statewide database.

00:45:37.000 --> 00:45:40.000
We aren't looking for your single-family home parcel map.

00:45:40.000 --> 00:45:47.000
Further, in this day of GIS mapping, LIDAR, and drones, people are mapping at larger and larger scales.

00:45:47.000 --> 00:45:49.000
I'm waiting for one-to-one to come out.

00:45:49.000 --> 00:46:00.000
And that's great for all kinds of things, but it's not right for this database. So if you've been mapping it 1 to 10, and have thousands of 5 meter long segments, we will not be able to incorporate that.

00:46:00.000 --> 00:46:07.000
We would like to represent your mapping, but it will have to be downsampled for this database to maybe 1 to 5,000 or smaller.

00:46:07.000 --> 00:46:11.000
And it's better that you do that downsampling than we do.

00:46:11.000 --> 00:46:16.000
Finally, just because you give us your mapping doesn't guarantee we will include it, but we will consider.

00:46:16.000 --> 00:46:20.000
And evaluate it.

00:46:20.000 --> 00:46:27.000
I'm going to finish it up with going over what I've been saying about the two databases are, and how they differ. Here's the final comparison slide.

00:46:27.000 --> 00:46:29.000
For AP zones,

00:46:29.000 --> 00:46:37.000
They are legally mandated by the AP Act and have regulatory implications. They're focused on Holocene surface faulting.

00:46:37.000 --> 00:46:42.000
And again, it's the zones that are important more than the fault traces.

00:46:42.000 --> 00:46:47.000
It's at a set scale of 1 to 24,000, and CGS does the mapping.

00:46:47.000 --> 00:46:53.000
For the quaternary fault database, it's informational and has no regulatory implications.

00:46:53.000 --> 00:46:56.000
It's focused on quaternary faults.

00:46:56.000 --> 00:47:05.000
And it is available with variable scales of mapping, and the community does the mapping.

00:47:05.000 --> 00:47:13.000
reiterate the answers to the question, how are faults added to and removed from the quaternary fault database in Alquis Priola zones? Here they are again.

00:47:13.000 --> 00:47:16.000
Basically, CGS makes and revises the A…

00:47:16.000 --> 00:47:18.000
P faults, and zones.

00:47:18.000 --> 00:47:20.000
based on available data.

00:47:20.000 --> 00:47:29.000
And for the quaternary fault database, CGS evaluates and compiles mapping produced by other investigators.

00:47:29.000 --> 00:47:34.000
Thanks a lot.

00:47:34.000 --> 00:47:38.000
Okay, let's thank Judy.

00:47:38.000 --> 00:47:41.000
Wonderful talk.

00:47:41.000 --> 00:47:46.000
I see a lot of applause coming in. Alright, and then we'll move on to our…

00:47:46.000 --> 00:47:50.000
Final talk of this session before we go into the discussion.

00:47:50.000 --> 00:47:54.000
Um, our next speaker is Danielle Mueller.

00:47:54.000 --> 00:47:58.000
In the city of Alameda, who will be speaking about addressing sea level rise

00:47:58.000 --> 00:48:03.000
And liquefaction in areas of Bay Phil, so onto our… our…

00:48:03.000 --> 00:48:09.000
other favorite earthquake ground deformation hazards, so please hit play, and…

00:48:09.000 --> 00:48:12.000
Let's roll.

00:48:12.000 --> 00:48:24.000
Hi, my name is Danielle Mueller. I'm the Sustainability and Resilience Manager for the City of Alameda, and I'm going to be talking about how we're addressing sea level rise and liquefaction in areas of Bay Phil in Alameda.

00:48:24.000 --> 00:48:32.000
Alameda Shoreline has undergone significant transformation over the last century. Much of the current shoreline was made by filling tidal marshes,

00:48:32.000 --> 00:48:36.000
mudflats and even open water to create developable land.

00:48:36.000 --> 00:48:40.000
The fill was generally not compacted and has high liquefaction potential.

00:48:40.000 --> 00:48:46.000
Areas were also not filled to a high elevation, and are susceptible to inundation from rising seas.

00:48:46.000 --> 00:48:52.000
We are now in a place where we're about to undergo another period of shoreline transformation, and our shoreline will continue to evolve.

00:48:52.000 --> 00:48:59.000
As we discuss this evolution, it's important to consider not only what we have to do to address the urgent risks posed by sea level rise,

00:48:59.000 --> 00:49:07.000
But also to imagine what is possible, and how adaptation can bring opportunity for positive change on the shoreline.

00:49:07.000 --> 00:49:16.000
Constructing flood protection infrastructure may allow us to expand public access by connecting the Bay Trail and building new waterfront parks.

00:49:16.000 --> 00:49:21.000
We also have opportunities to construct nature-based features that reduce flood risk while increasing habitat.

00:49:21.000 --> 00:49:30.000
Implementing green infrastructure to manage stormwater flooding can also provide habitat and increase the beauty and comfort of our city.

00:49:30.000 --> 00:49:37.000
Sea levels are rising, groundwater tables are rising, and precipitation intensity is increasing as a result of climate change.

00:49:37.000 --> 00:49:41.000
These risks will increase over time as the impacts to our communities will also grow.

00:49:41.000 --> 00:49:50.000
Without adaptation, rising seas and coastal flooding can overtop shorelines, causing damage to low-lying neighborhoods and to the shoreline.

00:49:50.000 --> 00:49:55.000
Rising groundwater pushed to the surface by rising sea levels can also impact communities from below.

00:49:55.000 --> 00:50:01.000
The maps here show how surface flooding will affect our communities with different levels of sea level rise.

00:50:01.000 --> 00:50:06.000
Blue shaded areas represent coastal flooding, with sea level rise plus an extreme tide.

00:50:06.000 --> 00:50:10.000
Darker blue indicates deeper flood water, lighter blue, shallower flood water.

00:50:10.000 --> 00:50:15.000
purple shaded areas represent where groundwater emerges above the ground surface.

00:50:15.000 --> 00:50:20.000
The vulnerability of our shoreline depends on elevation and exposure to waves from the bay.

00:50:20.000 --> 00:50:26.000
The areas of the shoreline constructed on former Tidal marsh or mudflat are especially vulnerable to coastal flooding.

00:50:26.000 --> 00:50:30.000
These areas are also at risk from liquefaction in an earthquake.

00:50:30.000 --> 00:50:33.000
And soil contaminants are at risk of becoming mobilized with

00:50:33.000 --> 00:50:39.000
rising groundwater and stormwater management infrastructure may need to be adapted to coordinate

00:50:39.000 --> 00:50:44.000
With shoreline flood defense, and remain functional with rising tides.

00:50:44.000 --> 00:50:50.000
In Alameda, we're already seeing the impacts of climate change, with more severe storms and more frequent flooding events.

00:50:50.000 --> 00:50:57.000
The December 2024 atmospheric river was associated with a king tide event that gives us a glimpse into our future.

00:50:57.000 --> 00:51:02.000
Again, in January of this year, we experienced another king tide and storm event.

00:51:02.000 --> 00:51:10.000
And our shoreline experienced significant erosion from both events, and infrastructure was threatened.

00:51:10.000 --> 00:51:19.000
Our approach to this challenge is to bring everyone together to work collaboratively. We know that we are stronger together, and Sea Overrise does not respectional boundaries.

00:51:19.000 --> 00:51:25.000
Alameda formed, uh, the Oakland-Alameda Adaptation Committee, or OAK as we call it, in 2021.

00:51:25.000 --> 00:51:32.000
As a coalition of shoreline communities, agencies, and stakeholders coordinating flood and sea level rise adaptation projects,

00:51:32.000 --> 00:51:38.000
Protecting and restoring water quality, habitat, and community resilience for the Oakland and Alameda sub-region.

00:51:38.000 --> 00:51:45.000
We meet quarterly as a large group and have a steering committee and sub-area working groups focused on specific project areas.

00:51:45.000 --> 00:51:50.000
We've successfully obtained significant funding to date for our collaborative projects.

00:51:50.000 --> 00:51:54.000
Which would not have been possible without this model.

00:51:54.000 --> 00:52:00.000
The Oak Project partners include key agencies, our paid community partners to lead grassroots community engagement,

00:52:00.000 --> 00:52:10.000
And our expert consultant team of landscape architects, climate scientists, coastal engineers, ecologists, biologists, civil and geotechnical engineers, and funding experts.

00:52:10.000 --> 00:52:16.000
We have many more members in our General Oak membership, from individual residents to state and federal agencies.

00:52:16.000 --> 00:52:21.000
We want to bring everyone together to solve these complex challenges.

00:52:21.000 --> 00:52:26.000
We know that parts of our community, including the places that we love, are vulnerable to flooding.

00:52:26.000 --> 00:52:34.000
While we won't be able to keep things exactly the same, we do have opportunities to protect and preserve the places that are most important to the community.

00:52:34.000 --> 00:52:38.000
Some of our priorities that we've determined through our community engagement process.

00:52:38.000 --> 00:52:44.000
include preserving South Shore Beach, maintaining recreational opportunities and shoreline access,

00:52:44.000 --> 00:52:48.000
Protecting residential neighborhoods and historic buildings and cultural districts.

00:52:48.000 --> 00:52:51.000
Preserving maritime uses and habitat.

00:52:51.000 --> 00:52:57.000
We'll continue to refine the list over time with input from the community as we move through the process.

00:52:57.000 --> 00:53:00.000
Some things won't stay exactly the same, though.

00:53:00.000 --> 00:53:03.000
There will be challenging trade-offs to be made in our future.

00:53:03.000 --> 00:53:07.000
However, it also presents opportunities. Some examples of opportunity…

00:53:07.000 --> 00:53:11.000
for change include nature and natural, uh, features,

00:53:11.000 --> 00:53:17.000
Recreational amenities, flood protection, stormwater management, new waterfront public open space,

00:53:17.000 --> 00:53:20.000
And increased economic diversity and opportunity.

00:53:20.000 --> 00:53:30.000
Earthquakes also present an opportunity for significant change on the shoreline. The areas that are subject to liquefaction need significant redevelopment and restoration after an earthquake.

00:53:30.000 --> 00:53:38.000
Adaptation plans in place can help guide and accelerate the rebuilding process, and similarly, shoreline adaptation in the absence of an earthquake

00:53:38.000 --> 00:53:44.000
can stimulate remediation efforts that can help address the liquefaction risk along the shoreline.

00:53:44.000 --> 00:53:47.000
Adaptation won't happen everywhere at all at once.

00:53:47.000 --> 00:53:51.000
The city and other land stewards will continue to take

00:53:51.000 --> 00:53:56.000
Immediate actions to address urgent risks while planning for adaptation further into the future.

00:53:56.000 --> 00:54:01.000
Near-term actions prioritize reducing risk associated with 0 to 2 feet of sea level rise.

00:54:01.000 --> 00:54:05.000
Largely focused on the lowest portion of the shoreline.

00:54:05.000 --> 00:54:10.000
Midterm actions will prepare us for risks associated with 2 to 3.5 feet of sea level rise.

00:54:10.000 --> 00:54:15.000
And long-term actions will consider risks associated with 3.5 to 7 feet of sea level rise.

00:54:15.000 --> 00:54:20.000
Final decision-making about this mid- and long-term actions will be made by future generations.

00:54:20.000 --> 00:54:24.000
But the decisions we make today influence the options that they will have.

00:54:24.000 --> 00:54:32.000
Earthquakes may speed up the timing of these actions if area of the shoreline experienced significant damage from liquefaction.

00:54:32.000 --> 00:54:41.000
And adaptation projects that happened before an earthquake may help reduce the risk of an earthquake by helping to reduce damage from liquefaction along the shoreline.

00:54:41.000 --> 00:54:50.000
One thing that still needs to be thought out more carefully in this planning is how to also address liquefaction further from the shoreline as part of an adaptation strategy.

00:54:50.000 --> 00:54:55.000
In addition to adaptation projects, Alameda's also working on a shoreline adaptation plan.

00:54:55.000 --> 00:55:05.000
This plan will comply with new state requirements. We've been working on a coordinated plan with Oakland over the last two years, and we've just been awarded an SB1 grant from the Ocean Protection Council

00:55:05.000 --> 00:55:13.000
To continue that effort and meet the BCDC regional shoreline Adaptation Planning requirements over the next two years for the City of Alameda.

00:55:13.000 --> 00:55:16.000
You can see where we are in the process and what's coming next.

00:55:16.000 --> 00:55:21.000
is to develop community-supported shoreline adaptation strategies and priority areas

00:55:21.000 --> 00:55:26.000
Recommending land use and policy updates, funding and implementation pathways,

00:55:26.000 --> 00:55:30.000
And then approval of the plan by the City Council and submission to BCDC.

00:55:30.000 --> 00:55:35.000
The plan will continue to include a robust community engagement process.

00:55:35.000 --> 00:55:44.000
And community engagement has been a big part of this process to date. We've been working hard to educate the community about the risks and solutions with our community partners leading the way.

00:55:44.000 --> 00:55:50.000
But shown here is pictures from our sea level rise planning fair that we held in September of last year.

00:55:50.000 --> 00:56:00.000
Um, the interactive family event attracted more than 150 participants to learn about the shoreline and provide their input on the vision for the future.

00:56:00.000 --> 00:56:06.000
So thank you for your time. My contact information is here if you have any further questions or want to follow up.

00:56:06.000 --> 00:56:14.000
On our website, we have boards with a lot of detailed information that was provided during our Sea Level Rise Planning Fair.

00:56:14.000 --> 00:56:16.000
And also on our project webpage.

00:56:16.000 --> 00:56:23.000
Thank you so much for your time, and I look forward to, um, answering questions and discussion.

00:56:23.000 --> 00:56:27.000
Thank you, Danielle. Okay, um…

00:56:27.000 --> 00:56:32.000
Nice round of applause for all of our speakers.

00:56:32.000 --> 00:56:37.000
And if we could bring all of our speakers on screen…

00:56:37.000 --> 00:56:40.000
join in a group photo.

00:56:40.000 --> 00:56:43.000
That would be great, if you're here, so…

00:56:43.000 --> 00:56:47.000
Judy, Austin, Danielle…

00:56:47.000 --> 00:56:50.000
Robert?

00:56:50.000 --> 00:56:54.000
Don't be shy. And then we can open this up for questions.

00:56:54.000 --> 00:56:58.000
Um, and please raise your hand. Thank you, Keith, for demonstrating.

00:56:58.000 --> 00:57:03.000
Raised hand. Um, and we'll call on you one by one, but I think…

00:57:03.000 --> 00:57:06.000
I don't know if Danielle's here?

00:57:06.000 --> 00:57:10.000
Um, I did have a question for her.

00:57:10.000 --> 00:57:11.000
I'm here.

00:57:11.000 --> 00:57:20.000
Oh, great! Yeah, so I'll exercise my privileges being moderator, and just ask you a quick question. You touched on soil contaminants being mobilized.

00:57:20.000 --> 00:57:26.000
Is there any effort to identify these high-risk areas in Alameda?

00:57:26.000 --> 00:57:32.000
assumed there might be some because of the military history there, and… and how to mitigate

00:57:32.000 --> 00:57:35.000
Future mobilization of…

00:57:35.000 --> 00:57:38.000
groundwater contaminants?

00:57:38.000 --> 00:57:53.000
Yeah, I think… thanks. Um, I think at the… at the former Naval Air Station, there is, you know, a real concerted effort to address the cleanups, and that cleanup is happening by the Navy before the land is transferred to the city of Alameda.

00:57:53.000 --> 00:58:00.000
So that process is still ongoing, and we're still in the… I think it's been 20 years since the Navy.

00:58:00.000 --> 00:58:05.000
closed, and they've been in phases, um, cleaning up and then transferring.

00:58:05.000 --> 00:58:13.000
To the city, um, there are other small, kind of, contaminated sites, um, throughout the rest of the city that.

00:58:13.000 --> 00:58:19.000
Um, we have mapped many of them were determined not to be hazardous because they're above the groundwater.

00:58:19.000 --> 00:58:25.000
table, and they can't, you know, they're contained, but as groundwater rises.

00:58:25.000 --> 00:58:37.000
There's potential for those sites to now mobilize, um… And I think it was in 2020, I can put a link in the chat, we did a groundwater rise study that was led by Dr. Chris May.

00:58:37.000 --> 00:58:43.000
Um, and she identified some of those… those risks and… and solutions.

00:58:43.000 --> 00:58:50.000
So, I have a question for Danielle as well.

00:58:50.000 --> 00:58:51.000
Yeah, hi.

00:58:51.000 --> 00:58:57.000
Is Alameda, or are you aware of other cities that are identifying areas that are so risky

00:58:57.000 --> 00:59:01.000
Um, due to the rising sea level and…

00:59:01.000 --> 00:59:05.000
The pour fill we have around the margins of the Bay Area that…

00:59:05.000 --> 00:59:08.000
that there might be areas where we just shouldn't redevelop.

00:59:08.000 --> 00:59:18.000
And it's always struck me that we should identify those before we have the next earthquake, when there's going to be tremendous pressure to just go ahead and redevelop right away.

00:59:18.000 --> 00:59:23.000
Um, is anyone… are any communities identifying those areas and…

00:59:23.000 --> 00:59:26.000
putting it into some sort of formal…

00:59:26.000 --> 00:59:33.000
code or regulation saying these areas shall not be redeveloped after the next earthquake.

00:59:33.000 --> 00:59:39.000
I think that is the biggest question, and I think that's something I think about a lot, is that.

00:59:39.000 --> 00:59:44.000
the liquefaction event is going to be our opportunity to probably retreat.

00:59:44.000 --> 00:59:49.000
Um, and if there's significant damage to buildings on the shoreline.

00:59:49.000 --> 01:00:01.000
Um, identifying… I think there's a… it's a catch-22, because if we identify those areas and say today they will not be redeveloped, those property owners immediately lose.

01:00:01.000 --> 01:00:05.000
Value, and… the City of All… the city, any city.

01:00:05.000 --> 01:00:09.000
Can't… it's a, you know, it's considered… it's basically a taking. We're taking their property.

01:00:09.000 --> 01:00:16.000
We can't afford to… we certainly can't afford to buy out all those properties, which is essentially what you would have to do.

01:00:16.000 --> 01:00:23.000
After the earthquake, people are going to want to rebuild as quickly as possible, and we would still need to buy out the properties.

01:00:23.000 --> 01:00:30.000
After the earthquake, in order to prevent them from being redeveloped. Like, the property owner has to be compensated.

01:00:30.000 --> 01:00:40.000
Further loss of property somehow, so… I… I don't know the answer to that. I don't… I don't know, and I don't think that any city.

01:00:40.000 --> 01:00:51.000
can make that… that determination. Without bearing significant cost and liability.

01:00:51.000 --> 01:00:53.000
Thanks.

01:00:53.000 --> 01:00:56.000
Christy had her hand up, I don't know.

01:00:56.000 --> 01:01:01.000
Do you want to ask a question, Christy?

01:01:01.000 --> 01:01:04.000
Did you put it back down?

01:01:04.000 --> 01:01:08.000
I didn't have my hand up, but I'm really enjoying the discussion in the chat.

01:01:08.000 --> 01:01:16.000
Uh, there's, um, we mentioned that Incline Village School was closed on account of there was, like, a giant fault scarp

01:01:16.000 --> 01:01:20.000
Um, projected into the schoolyard and perhaps under one of the buildings.

01:01:20.000 --> 01:01:27.000
There's no requirements in Nevada at all about identifying or investigating for active faults before constructing anything.

01:01:27.000 --> 01:01:32.000
Um, so we're a long way behind on that, obviously. Um, but as a first step, we are…

01:01:32.000 --> 01:01:39.000
Uh, working on some of our fault mapping, which was also compiled off 1930s aerofodial liniments, and there, like, all kinds of…

01:01:39.000 --> 01:01:42.000
Dog's breakfast in the Q Faults map. So…

01:01:42.000 --> 01:01:49.000
Anyway, I've been in occasional contact with Judy. Obviously, she can't help us with Nevada, but, um, it's just really…

01:01:49.000 --> 01:01:54.000
important to start with a good fault map. Um, and there was actually…

01:01:54.000 --> 01:02:01.000
some of the faults that are in Nevada have been shifted over 200 or 300 meters during digitizing.

01:02:01.000 --> 01:02:06.000
So, even where there is adequate mapping, it's not properly available in the USGS, um,

01:02:06.000 --> 01:02:09.000
dynamic website, which is where all the consultants go, so…

01:02:09.000 --> 01:02:16.000
Anyway, just here picking up tips.

01:02:16.000 --> 01:02:19.000
I see in the chat there's a lot of, uh,

01:02:19.000 --> 01:02:24.000
questions about… that were really answered by Danielle Madugo in her talk.

01:02:24.000 --> 01:02:27.000
Earlier in this meeting about, um…

01:02:27.000 --> 01:02:29.000
the impacts of Austin's recent work.

01:02:29.000 --> 01:02:35.000
on AP zoning, and I wonder if Danielle might just provide us a…

01:02:35.000 --> 00:00:00.000
Paragraph summary of her talk from the other day in response to that question.

00:00:00.000 --> 00:00:30.000
No, no thank you.

01:02:42.000 --> 01:02:47.000
I'll post, uh, one of my figures.

01:02:47.000 --> 01:02:51.000
Thank you.

01:02:51.000 --> 01:02:56.000
So, I did see a question, um, maybe we'll do a little more scientific question, um, from Ruth.

01:02:56.000 --> 01:03:01.000
And I'm not sure, I flew by, and I'm not sure if it was answered by Austin, but…

01:03:01.000 --> 01:03:07.000
Um, so Ruth asked, what do you think about the depth extent of creep?

01:03:07.000 --> 01:03:20.000
Uh, yeah, so that's a really great and a really important question, especially given what I said about, you know, we're learning all these different processes, uh, the time dependence and spatial variability and propagation of creep and things like this, so…

01:03:20.000 --> 01:03:28.000
Um, my work, just mapping out this trace doesn't really address that. Um, we did talk a little in the chat, or as I mentioned,

01:03:28.000 --> 01:03:34.000
Um, a lot of the offsets, the deflections, are across sort of a 10 or 15 meter wide zone.

01:03:34.000 --> 01:03:44.000
That suggests that the creep is happening maybe, like, at least that deep down, and the overlying layer is bending.

01:03:44.000 --> 01:04:02.000
But at, uh… yeah, you would want to go to longer-scale measurements of the deflection over time, and I think, um, in satellite INSAR and UAV SAR, yeah, there's a great figure from Danielle Madugo that she just put in the chat,

01:04:02.000 --> 01:04:04.000
Um, showing the INSAR.

01:04:04.000 --> 01:04:08.000
um… offsets, and I think there's even a prof…

01:04:08.000 --> 01:04:11.000
Uh, no, not a profile on that one.

01:04:11.000 --> 01:04:14.000
Anyway, the, uh…

01:04:14.000 --> 01:04:21.000
There is… the data probably needs to be, like, processed and analyzed more, but as I recall, basically, there's a…

01:04:21.000 --> 01:04:25.000
pretty good, just simple step function across the fault.

01:04:25.000 --> 01:04:28.000
Um, that extends for several kilometers in either direction, like,

01:04:28.000 --> 01:04:33.000
flat, so that suggests that the creep… that the steady velocity differential is

01:04:33.000 --> 01:04:39.000
widespread and thus deep, um, across the fault.

01:04:39.000 --> 01:04:41.000
Thank you, Ashton. And I really liked your talk, too.

01:04:41.000 --> 01:04:45.000
And I liked all the other talks. I learned so much, yes, thank you.

01:04:45.000 --> 01:04:51.000
See, uh, Don Hoyerup from DWR has his hand up. Don, you wanna unmute yourself?

01:04:51.000 --> 01:04:52.000
Fire away.

01:04:52.000 --> 01:04:55.000
Yeah, hi, Don Hart with Department of Water Resources. Uh, question for Judy.

01:04:55.000 --> 01:05:01.000
Uh, Judy, if a AP zone map has been released or revised,

01:05:01.000 --> 01:05:11.000
say, one year, and a consultant goes out and does work, and other geologists verify their findings that there does not appear to be a trace of a fault.

01:05:11.000 --> 01:05:25.000
that has been mapped. How long until that map will be revised to reflect that new finding?

01:05:25.000 --> 01:05:26.000
Okay.

01:05:26.000 --> 01:05:32.000
That is undefined. It… you know, it's… it really depends on.

01:05:32.000 --> 01:05:38.000
That sort of set of priorities that we were… that I mentioned.

01:05:38.000 --> 01:05:46.000
in the talk that, you know, there's… is, you know, what is the implication.

01:05:46.000 --> 01:05:55.000
of the information. in terms of, is it a place where people are building houses? Is it a place where, you know.

01:05:55.000 --> 01:06:04.000
Development is… happening, or has happened, all those things go into how we prioritize. We don't really have.

01:06:04.000 --> 01:06:08.000
the staff to just, like, do all of the faults.

01:06:08.000 --> 01:06:14.000
at once. So, um… Yeah, we're, you know, picking and choosing.

01:06:14.000 --> 01:06:21.000
I also want to. clarify that, you know, doing one investigation in a zone.

01:06:21.000 --> 01:06:27.000
And not finding the fault. is not enough.

01:06:27.000 --> 01:06:35.000
for us to decide. to rezone it. The zones are… A thousand feet wide.

01:06:35.000 --> 01:06:42.000
centered on our best geomorphic mapping. for where the… the main fault is.

01:06:42.000 --> 01:06:48.000
Um, most investigations in that zone are not going to find a fault.

01:06:48.000 --> 01:06:55.000
So, it really has to be, like, a series of… like, I mentioned with.

01:06:55.000 --> 01:07:01.000
Gordon's, it was… You know, that had… that fault had been zoned.

01:07:01.000 --> 01:07:06.000
And so there were a lot of investigations, and none of them.

01:07:06.000 --> 01:07:14.000
found a fault. That was what drove him to say, I don't think this is a whole CNACI fault.

01:07:14.000 --> 01:07:23.000
So 1 isn't adequate to do it. We aren't saying, you know, if you go to where we've drawn our line.

01:07:23.000 --> 01:07:27.000
That that is exactly where the fault is. That's why.

01:07:27.000 --> 01:07:33.000
The consultants do the site-specific investigations, and they find out exactly where.

01:07:33.000 --> 01:07:43.000
the fault is, or isn't. Um… So, there has to be kind of a body of work.

01:07:43.000 --> 01:07:46.000
to support, um… prioritizing revising a zone.

01:07:46.000 --> 01:07:51.000
Okay, and just as a follow-up to that, Judy, that explains it well.

01:07:51.000 --> 01:07:56.000
Um, if it is determined by CGS, um,

01:07:56.000 --> 01:08:00.000
that the fault should be removed.

01:08:00.000 --> 01:08:05.000
Would a, um, a developer be able to check some database that says,

01:08:05.000 --> 01:08:14.000
Hey, I'm looking at a map that shows it in the zone, but very recently, it's been taken out, but the new maps haven't been released. You know, is there a way

01:08:14.000 --> 01:08:24.000
To find that out, or does someone just call yourself and say, hey, was this area taken out recently?

01:08:24.000 --> 01:08:29.000
So, even if you call me, I'm not going to say that until.

01:08:29.000 --> 01:08:30.000
Okay, yeah, very good.

01:08:30.000 --> 01:08:32.000
the maps come out. Um… yeah.

01:08:32.000 --> 01:08:34.000
Yeah.

01:08:34.000 --> 01:08:38.000
So they'll go out as preliminary maps for review.

01:08:38.000 --> 01:08:42.000
in, you know, in the spring, and then people can look at them.

01:08:42.000 --> 01:08:49.000
Um, and then they don't become official for 6 months later, till 6 months later.

01:08:49.000 --> 01:08:54.000
But yeah, until that review period is done and the official maps come out.

01:08:54.000 --> 01:08:57.000
I'm not going to say that the. Trace has been removed.

01:08:57.000 --> 01:09:03.000
Very good. Thank you.

01:09:03.000 --> 01:09:07.000
Looks like Christy has her hand up.

01:09:07.000 --> 01:09:11.000
Thanks, um, uh, I was wondering about…

01:09:11.000 --> 01:09:17.000
the… things like the swarm, where Dave Shelley was showing us the delineation of some clearly active faults,

01:09:17.000 --> 01:09:28.000
that extend, um, kind of in a north-south direction that would nicely connect the end of the AP zone at San Ramon from the Calaveras to the end of the AP zone into Concord Fault.

01:09:28.000 --> 01:09:30.000
If recognized as an active structure.

01:09:30.000 --> 01:09:32.000
So, I realized that

01:09:32.000 --> 01:09:38.000
like, the important criteria is, like, evidence of previous surface displacement.

01:09:38.000 --> 01:09:48.000
But, um, and this would actually work really well in Nevada, where we have structures that don't daylight, but we have, like, quite a significant amount of activity, swarm activity on them. Like, it would…

01:09:48.000 --> 01:09:54.000
Would that ever qualify, do you think? I mean, maybe it would take it back to the legislature, but this is an act of fault.

01:09:54.000 --> 01:10:00.000
The San Ramon swarms popped off as he showed us, like, maybe 8 times in the last… in my lifetime.

01:10:00.000 --> 01:10:03.000
Um, probably on these similar structures.

01:10:03.000 --> 01:10:04.000
Certainly a…

01:10:04.000 --> 01:10:08.000
Yeah. For the AP Act, it's… it's… specifically surface rupture.

01:10:08.000 --> 01:10:10.000
Okay, past surface rupture only.

01:10:10.000 --> 01:10:15.000
And if you… and it has to be… well-defined.

01:10:15.000 --> 01:10:19.000
Because you have to be able to actually sort of say this is.

01:10:19.000 --> 01:10:39.000
You know, not in every little. piece of the fault? Is it necessarily going to be well-defined? But… Um… it has to be reasonably well-defined as a fault, and then you might, you know, connect undefined sections between.

01:10:39.000 --> 01:10:46.000
two well-defined sections, but, um. Yeah, if it's just kind of, hey, there are earthquakes here.

01:10:46.000 --> 01:10:49.000
It's not going to meet the criteria.

01:10:49.000 --> 01:10:54.000
So, oh, all you have to do is change the name of the conquered fault to the North-North Calaveras.

01:10:54.000 --> 01:11:01.000
And then you can connect them.

01:11:01.000 --> 01:11:04.000
That's your proposal.

01:11:04.000 --> 01:11:08.000
I see Bob and Coughlin has his hand up.

01:11:08.000 --> 01:11:10.000
Bob?

01:11:10.000 --> 01:11:14.000
Um, yeah, it would seem to me that in this regard, um.

01:11:14.000 --> 01:11:20.000
Especially over in the East Bay fault system, and faults that step over to the.

01:11:20.000 --> 01:11:27.000
Bartlett Springs, Fault Zone, as it's been acknowledged, this is a very.

01:11:27.000 --> 01:11:32.000
complicated system of faults, and there's lots of stepovers, both releasing.

01:11:32.000 --> 01:11:43.000
And restraining bins. And it would seem that, uh, and several of those areas, uh, do exhibit micro-seismicity.

01:11:43.000 --> 01:11:54.000
Even though you don't have rupturing that has made it to the surface. And I'm… I'm sort of… Thinking that it would be good to have some.

01:11:54.000 --> 01:12:01.000
kind of a category in the. In the fault, um, zoning, um.

01:12:01.000 --> 01:12:14.000
Uh, for… specifically for… pointing to areas of, uh, releasing bends and restraining bends where they're obviously connected to.

01:12:14.000 --> 01:12:19.000
Uh, through growing, uh, major. fault system at depth.

01:12:19.000 --> 01:12:25.000
Um, so that's just a comment I wanted to make in regard to.

01:12:25.000 --> 01:12:32.000
Um, Christy's comment and… and Judy's, um… Um, reaction.

01:12:32.000 --> 01:12:37.000
Yeah, I guess I… This is a law.

01:12:37.000 --> 01:12:45.000
And so, it's not… Like, just… geology best practices.

01:12:45.000 --> 01:12:56.000
So, we're a little bit constrained in. what we can do that has regulatory implications, that it has to follow.

01:12:56.000 --> 01:13:05.000
the constraints of the law. And… so, you know, we could, in our fault evaluation reports.

01:13:05.000 --> 01:13:12.000
talk about that. Um… But in terms of actually doing something with the zone.

01:13:12.000 --> 01:13:18.000
we kind of have to follow. Then.

01:13:18.000 --> 01:13:23.000
pretty defined. constraints that we have.

01:13:23.000 --> 01:13:26.000
In terms of what we can… we have to be able to draw a line.

01:13:26.000 --> 01:13:32.000
and put a zone around it, kind of. you know.

01:13:32.000 --> 01:13:33.000
Yeah.

01:13:33.000 --> 01:13:48.000
Yeah. Okay, well, I understand the issue, and uh… It extends to, um… Other things like landsliding as well, so, um, it's… it's the same… problem of, of, uh… staying within the law, as it's written.

01:13:48.000 --> 01:13:49.000
And, um… property owner's rights, and that sort of thing, yeah. Thank you.

01:13:49.000 --> 01:13:57.000
Yeah. Which… Yeah. The law is often a blunt instrument.

01:13:57.000 --> 01:13:58.000
Robert has his hand up. Go ahead, Robert.

01:13:58.000 --> 01:14:01.000
Thanks.

01:14:01.000 --> 01:14:09.000
You're next.

01:14:09.000 --> 01:14:10.000
You're muted.

01:14:10.000 --> 01:14:15.000
Still muted.

01:14:15.000 --> 01:14:17.000
No sound.

01:14:17.000 --> 01:14:21.000
Sorry.

01:14:21.000 --> 01:14:24.000
We'll go on to another question while maybe you can…

01:14:24.000 --> 01:14:29.000
Do you solve your technical difficulties, because I had a question for you, so hopefully we can fix that.

01:14:29.000 --> 01:14:35.000
Um, um, Chris Madugo, you had a question in the chat, and I think it's a good one for both, um,

01:14:35.000 --> 01:14:38.000
maybe Judy and Austin, to some extent.

01:14:38.000 --> 01:14:40.000
Um, if you're…

01:14:40.000 --> 01:14:50.000
around. Why don't you pop up on screen and ask your question?

01:14:50.000 --> 01:14:51.000
dueling computers.

01:14:51.000 --> 01:14:52.000
Then you'll need some treatment, doctor.

01:14:52.000 --> 01:15:03.000
Alright, okay, so my question was… Um, has there been a systematic evaluation of the creeping faults in the Bay Area to see if there's any other.

01:15:03.000 --> 01:15:19.000
Um, strands that have been missed. Um, you know, we did an evaluation for one of our gas pipelines in the vicinity of where the new strand was… Not a new strand, previously unmapped strand.

01:15:19.000 --> 01:15:34.000
Um, and the faulting looked a little weird there, as mapped. We didn't find the new strand or anything, but I know that there's kind of areas along the Hayward and other faults that kind of have similar issues, so has someone kind of sat down.

01:15:34.000 --> 01:15:42.000
And just kind of systematically looked along all these faults, and… And, uh, looked at previous mapping to see if there were any.

01:15:42.000 --> 01:15:44.000
disconnects.

01:15:44.000 --> 01:15:50.000
So, Judy will have a different answer to this, which is probably more relevant and important than mine, but I'll, um…

01:15:50.000 --> 01:15:59.000
I… I think the… an interesting aspect of this is that we don't tend to map the faults with this level of precision or detail.

01:15:59.000 --> 01:16:03.000
Um, and there's not necessarily a…

01:16:03.000 --> 01:16:09.000
So there's not necessarily a widespread prerogative to…

01:16:09.000 --> 01:16:18.000
do that, or there hasn't been, right? I mean, it takes a lot of work, also, to actually go out in such detail and capture these things, but it is possible now, and especially with the creeping faults,

01:16:18.000 --> 01:16:29.000
You really… yeah, I mean, those of you who live in the Bay Area and who visit all these places, you see they're beautifully expressed everywhere, and the small-scale

01:16:29.000 --> 01:16:35.000
geomorphology and structures that they create are very conspicuous, and so you can accomplish

01:16:35.000 --> 01:16:39.000
ridiculously high precisions of mapping.

01:16:39.000 --> 01:16:47.000
So, it's a… I think it's a good idea. It's a possibility to do that, um, if people want to. There have been, um, I think,

01:16:47.000 --> 01:16:53.000
there were projects on some external grants from the USGS that accomplished, um, for example, remapping of the

01:16:53.000 --> 01:16:56.000
Calavera's fault, um, and…

01:16:56.000 --> 01:17:00.000
Other things that, you know, just bringing to…

01:17:00.000 --> 01:17:02.000
there was a lot of mapping done in the 70s, 80s, and…

01:17:02.000 --> 01:17:13.000
things were captured really well, and things have been updated into digital formats with varying studies all over the place, but very rarely with this really super high precision that, like, shows exactly where the…

01:17:13.000 --> 01:17:18.000
Creeping Trace is running across, for example, even a single street.

01:17:18.000 --> 01:17:22.000
Um…

01:17:22.000 --> 01:17:26.000
So there hasn't been a systematic, uh,

01:17:26.000 --> 01:17:34.000
tackling of that yet, um, but it would be possible.

01:17:34.000 --> 01:17:35.000
The answer is no.

01:17:35.000 --> 01:17:44.000
I'll just… yeah, I'll just… maybe I'll just add on quick. Chris, that's a great question, and I… just in total agreement with Austin, and Austin's… Study's a nice example. I think.

01:17:44.000 --> 01:17:53.000
the way it's happening in reality is that we wait for the remote sensors, especially the SAR folks, to give us some insight into what's happening out there, because it's really hard to just.

01:17:53.000 --> 01:18:20.000
drive around looking for offset curbs. And so, we really rely on the SAR folks in particular, and there's some excitement about the NYSAR project coming online. Uav SAR has been great, but improving SAR and the remote sensing of fault creep is sort of the way to do this, more so than… some sort of systematic mapping. And so, in practice, we often chase what we see in remote sensing, and then, um, evaluate things in more detail when things pop out of that.

01:18:20.000 --> 01:18:21.000
Austin's got something to follow up on.

01:18:21.000 --> 01:18:29.000
Uh, yeah, I think I'll add also that there is… I think there was maybe a bit of an era when the mapping was sufficient, and then…

01:18:29.000 --> 01:18:37.000
We got higher, you know, we now have satellite and LiDAR and all these technologies that allow us to do much higher precision fault mapping.

01:18:37.000 --> 01:18:41.000
Um, but the scientific motivations didn't necessarily catch up until

01:18:41.000 --> 01:18:47.000
More recently, and I think now, there are a lot of… there's growing momentum around these motivations of understanding

01:18:47.000 --> 01:18:54.000
the nature of fault creep, mechanistically, uh, when we… as we recognize the

01:18:54.000 --> 01:19:07.000
the time variability of it, the space variability of it, uh, the material properties, and then fault zone structures. We've heard, like, a lot of talks already about this sort of stuff from Josie, um, from Bell, looking at the Central San Andreas.

01:19:07.000 --> 01:19:09.000
Um, there are tons of other people, sort of,

01:19:09.000 --> 01:19:12.000
thinking about these questions, but, um…

01:19:12.000 --> 01:19:23.000
understanding the actual fault zone structure is increasingly relevant to understand the rupture process and… or slip processes in general, and so that, I think,

01:19:23.000 --> 01:19:36.000
provides a nice scientific motivation for going out and saying, hey, where there… so, we know there's a creeping Hayward Fault. Even places where it crosses a street, you see these on-echelon strands over, like, a small scale.

01:19:36.000 --> 01:19:41.000
that has mechanical implications for what to expect in surface rupturing.

01:19:41.000 --> 01:19:43.000
Well, that is surface rupture, and…

01:19:43.000 --> 01:19:54.000
It's happening for mechanical reasons that can be studied and understood.

01:19:54.000 --> 01:19:57.000
I've got a question for Robert, if…

01:19:57.000 --> 01:20:03.000
He's, uh, feels like he's up for answering.

01:20:03.000 --> 01:20:08.000
I appreciate the care you took, Robert, in describing

01:20:08.000 --> 01:20:13.000
Um, your data and your results from those data, and…

01:20:13.000 --> 01:20:21.000
And I'm… what I'm wondering about is how you think about recency of activities lessons that might be learned from

01:20:21.000 --> 01:20:23.000
your studies. I appreciated that…

01:20:23.000 --> 01:20:31.000
There were times during your presentation when you mentioned that such and such a feature approaches to within 10 or 25 meters of the surface.

01:20:31.000 --> 01:20:35.000
And thanks for being so clear about that.

01:20:35.000 --> 01:20:37.000
I imagine that…

01:20:37.000 --> 01:20:41.000
Uh, there are… there are…

01:20:41.000 --> 01:20:47.000
times when you'd like to be more definitive, or just throw out there, this is a freaking active vault.

01:20:47.000 --> 01:20:52.000
Um, so how do you think about your studies with respect to…

01:20:52.000 --> 01:20:56.000
Um, recency of activity and…

01:20:56.000 --> 01:20:59.000
follow up with other kinds of…

01:20:59.000 --> 01:21:03.000
of studies to demonstrate or document recency of activity.

01:21:03.000 --> 01:21:05.000
Okay, well, can you hear me now? Is it working?

01:21:05.000 --> 01:21:06.000
Yep.

01:21:06.000 --> 01:21:08.000
Finally, the brand new headset.

01:21:08.000 --> 01:21:11.000
Um…

01:21:11.000 --> 01:21:14.000
Well, uh…

01:21:14.000 --> 01:21:17.000
It's clear those faults are pretty near the surface.

01:21:17.000 --> 01:21:19.000
So…

01:21:19.000 --> 01:21:22.000
given how much, you know,

01:21:22.000 --> 01:21:25.000
anthropological disturbance there's been.

01:21:25.000 --> 01:21:30.000
they could be trenched in a very large excavation, something…

01:21:30.000 --> 01:21:34.000
big pipeline or something.

01:21:34.000 --> 01:21:42.000
we can… the thing about seismic imaging is it's totally scalable. You know, we can do anything from your backyard to across the continent.

01:21:42.000 --> 01:21:49.000
we can go back to those areas, and if we want to do more detail, do an even more detailed

01:21:49.000 --> 01:21:54.000
study that would focus in on the very, very near surface, if we wanted to try to chase

01:21:54.000 --> 01:21:56.000
Traces up to the close.

01:21:56.000 --> 01:21:59.000
That being said, I think…

01:21:59.000 --> 01:22:05.000
what we've found definitely would fall into…

01:22:05.000 --> 01:22:12.000
consideration for AP, because they're clearly very close to the surface. We know, for example, the, um…

01:22:12.000 --> 01:22:14.000
Uh, to the south, the, uh…

01:22:14.000 --> 01:22:17.000
Alameda Dallas Pulgus Fault.

01:22:17.000 --> 01:22:19.000
is pretty much at the surface.

01:22:19.000 --> 01:22:23.000
I don't know that anyone has any… I can't remember the…

01:22:23.000 --> 01:22:28.000
the mapping, what it's classified as in terms of its age.

01:22:28.000 --> 01:22:31.000
But… we know if that's…

01:22:31.000 --> 01:22:37.000
what we're showing, if that really does march along to north of the Sarah, we know the Sarah's been Holocene active.

01:22:37.000 --> 01:22:40.000
That's been trenched. That was done by, uh…

01:22:40.000 --> 01:22:44.000
John, Wakabayashi and co… uh…

01:22:44.000 --> 01:22:47.000
Get the other gentleman. Uh, anyway…

01:22:47.000 --> 01:22:51.000
We know that faults Holocene active. If that's the same structure,

01:22:51.000 --> 01:22:53.000
And then we know that's…

01:22:53.000 --> 01:22:56.000
Where, you know, much more problematic.

01:22:56.000 --> 01:22:58.000
Um…

01:22:58.000 --> 01:23:02.000
I guess…

01:23:02.000 --> 01:23:06.000
I think they should be considered for AP, at least…

01:23:06.000 --> 01:23:12.000
something to be… be considered, you know, maybe given the fact that they're completely paved,

01:23:12.000 --> 01:23:15.000
that the near-surface record's destroyed, you can't really tell.

01:23:15.000 --> 01:23:18.000
But certainly for…

01:23:18.000 --> 01:23:20.000
larger infrastructure.

01:23:20.000 --> 01:23:22.000
They certainly should be looked at.

01:23:22.000 --> 01:23:25.000
In fact, we'd like to do more. I mean, we'd like to…

01:23:25.000 --> 01:23:29.000
We're kind of… I was going to get into this a little bit, but…

01:23:29.000 --> 01:23:37.000
we would love to map these things in detail up and down the whole peninsula. It's kind of a catch-22 situation. We can't do…

01:23:37.000 --> 01:23:41.000
The big, grandiose experiment we'd like to do to map them safe from Los Gatos.

01:23:41.000 --> 01:23:44.000
up to Daly City, because that would require

01:23:44.000 --> 01:23:46.000
Shall we say a much more…

01:23:46.000 --> 01:23:52.000
higher energy sources that we can use in the more rural area, we can't use them in an urban setting.

01:23:52.000 --> 01:23:55.000
So we kind of have to do this piecemeal, and so we're getting…

01:23:55.000 --> 01:23:57.000
you know, dots on the map.

01:23:57.000 --> 01:24:00.000
Um, but I…

01:24:00.000 --> 01:24:09.000
think of what we're doing as important, and I think it definitely shows there are near-surface structures that should be investigated in more detail.

01:24:09.000 --> 01:24:13.000
Thanks.

01:24:13.000 --> 01:24:14.000
Yes, he…

01:24:14.000 --> 01:24:16.000
Have you spoken to Gordon, who is… Currently evaluating the Seraphart Fault.

01:24:16.000 --> 01:24:21.000
He emailed me a while… I gave a presentation a while back, and he…

01:24:21.000 --> 01:24:27.000
He said, hey, I think I want to map that, and I… I never heard from him again, but I know we've…

01:24:27.000 --> 01:24:29.000
exchanged, you know, an email about that.

01:24:29.000 --> 01:24:31.000
And like I said, we would like to do this up and down the rest of the peninsula. It's just…

01:24:31.000 --> 01:24:35.000
Okay.

01:24:35.000 --> 01:24:43.000
This work is extremely challenging in an urban environment, from a logistics point of view. The science part of it's actually

01:24:43.000 --> 01:24:48.000
Easy. It's the logistics of working in an urban environment that are tricky.

01:24:48.000 --> 01:24:49.000
And we'd love to do more. I mean, we live here too, you won't… we want to know what's going on.

01:24:49.000 --> 01:24:53.000
Yeah.

01:24:53.000 --> 01:24:56.000
So…

01:24:56.000 --> 01:24:58.000
And when's got some money they want to throw at this.

01:24:58.000 --> 01:25:02.000
We're all ears.

01:25:02.000 --> 01:25:04.000
Robert, I had a quick follow-up question.

01:25:04.000 --> 01:25:05.000
Yeah.

01:25:05.000 --> 01:25:13.000
And maybe it's a… maybe it's more aimed at the Earthquake geology group there at the USGS, but it seems like a paired study of this

01:25:13.000 --> 01:25:17.000
astrology of physics, and then trenching paleoseismic trenching to

01:25:17.000 --> 01:25:24.000
better understand the characteristics of the faults in the near surface would be really interesting. Has that been done?

01:25:24.000 --> 01:25:29.000
Well, like I said, the only case that I know for that sort of zone, there's not

01:25:29.000 --> 01:25:34.000
much going on is just outside of it. To the north is the Sarah that Wakabayashi trenched.

01:25:34.000 --> 01:25:38.000
I don't know of any…

01:25:38.000 --> 01:25:40.000
detailed, sort of…

01:25:40.000 --> 01:25:44.000
paleo seismic work that's been done on the rage front from

01:25:44.000 --> 01:25:50.000
say that, uh, San Bruno, southward to San Carlos. I don't… if it exists, I don't know about it.

01:25:50.000 --> 01:25:52.000
I think it hasn't happened.

01:25:52.000 --> 01:25:55.000
It would be nice. But like I said,

01:25:55.000 --> 01:25:57.000
you know, given… you could probably

01:25:57.000 --> 01:26:03.000
do some work on the range front, uh, while Gallabi does Polgus. There might be a few spots where there's some undisturbed…

01:26:03.000 --> 01:26:06.000
natural.

01:26:06.000 --> 01:26:10.000
ground, but, like, the faults that were under the city of San Carlos.

01:26:10.000 --> 01:26:14.000
Who knows how much of that upper record's been obliterated by human activity.

01:26:14.000 --> 01:26:22.000
I mean, you know, the eucalyptus Avenue, that was a wonderful test case because there's nothing buried under the street. So, what underneath

01:26:22.000 --> 01:26:26.000
the shallow foot of human disturbance should be natural.

01:26:26.000 --> 01:26:33.000
material. In the Howard Street, though, we know there's pipelines, there's sewer lines and stuff, and so we don't know what's been…

01:26:33.000 --> 01:26:36.000
In terms of any kind of record has been…

01:26:36.000 --> 01:26:38.000
damaged from that kind of work.

01:26:38.000 --> 01:26:41.000
Not saying it can't be done, but…

01:26:41.000 --> 01:26:43.000
Uh, it would be…

01:26:43.000 --> 01:26:46.000
tricky to find a spot.

01:26:46.000 --> 01:26:54.000
Robert Tyler has a question in the chat about, um, comparing the year results and the location of your fault maps against

01:26:54.000 --> 01:27:02.000
some geomorphic work done looking at stream terrace profiles, or stream profiles, and perhaps stream terrace profiles.

01:27:02.000 --> 01:27:09.000
Yeah, there was a field trip that I wasn't able to go on, I do remember… I have, like, the field guide for that, but I haven't looked

01:27:09.000 --> 01:27:13.000
at any… I haven't… I don't have the details of that to…

01:27:13.000 --> 01:27:17.000
I would love to, if he's got… if you can share more info about that.

01:27:17.000 --> 01:27:21.000
Yeah, we could certainly chat about it.

01:27:21.000 --> 01:27:23.000
I think Bob has the same one.

01:27:23.000 --> 01:27:24.000
I wanted to jump in, this is Chris, can you hear me?

01:27:24.000 --> 01:27:26.000
Oh, sorry, go ahead, Chris.

01:27:26.000 --> 01:27:38.000
Um… PHE sponsored some of those geomorphic studies connecting the map trace of the Seraphalt further to the south, because it looked like, geomorphically, the fault should continue, but it just.

01:27:38.000 --> 01:27:48.000
kind of disappeared into Franciscan. So, Infatera and Drew Kennedy, um, David Trench, who's no longer with Infatera, but he works for the state.

01:27:48.000 --> 01:27:58.000
They did these geomorphic analyses. They're not written up in the published literature, but the results were presented.

01:27:58.000 --> 01:28:08.000
Um, at field trips and, uh… in abstract, so, um, you know, Gordon, for his mapping, should reach out to those folks, and… Robert, you should talk to those folks as well.

01:28:08.000 --> 01:28:10.000
Okay.

01:28:10.000 --> 01:28:12.000
Cross. Alright, Bob?

01:28:12.000 --> 01:28:17.000
You've had… patiently had your hand up for a while, so let's go to you.

01:28:17.000 --> 01:28:31.000
Yeah, this is, uh, Bob McLaughlin, um… Yeah, I've, um… Um, as many of you may know, I've been involved with, um, off and on.

01:28:31.000 --> 01:28:43.000
for decades with, uh… fault system, range front faults, um… further to the south in the, uh, area, uh, from Los Gatas.

01:28:43.000 --> 01:28:51.000
northward, um… upward, uh, north… at least, uh, up to the Palo Alto Menlo Park area.

01:28:51.000 --> 01:29:09.000
And, uh, those faults. You know, clearly are, uh, have been shown to be, um… Pleistocene or younger in age, in many trench investigations over the years. The trick has always been.

01:29:09.000 --> 01:29:17.000
to, um… uh, find, uh, rupturing that goes up into, up into, um.

01:29:17.000 --> 01:29:24.000
Um… demonstrable Holacine.

01:29:24.000 --> 01:29:28.000
uh, features in, uh, and actually rupture the surface.

01:29:28.000 --> 01:29:37.000
Those faults are very challenging to demonstrate. policy and displacement on, and part of it has to do with.

01:29:37.000 --> 01:29:41.000
the fact that, that, um, most of the movement on those.

01:29:41.000 --> 01:29:47.000
fault is, uh… been shown to be, um, thrust.

01:29:47.000 --> 01:29:56.000
reverse fault in nature. And, uh, they, uh, root back towards, uh, the San Andreas Fault, and there's, uh.

01:29:56.000 --> 01:30:01.000
Most of us know that, um, in the Loma Prieta earthquake, there was triggered slip.

01:30:01.000 --> 01:30:07.000
on those faults in the Los Gatas, um. Loma Prieta area.

01:30:07.000 --> 01:30:13.000
So, um, to the extent that, that. Bob is mapping some of the.

01:30:13.000 --> 01:30:22.000
the more outboard strands of that fault system. in the San Carlos area, um… That is why I sort of urged.

01:30:22.000 --> 01:30:31.000
Him to continue. His work further… to the southwest towards the San Andreas.

01:30:31.000 --> 01:30:41.000
And actually, um, cross into the upland area. And that's why I suggested Britton Avenue or Edgewood Road.

01:30:41.000 --> 01:30:50.000
And, um, um… One of the things that is noticeable in the, for instance, in the Edgewood Park area.

01:30:50.000 --> 01:30:55.000
Um, uh, that. there is clearly.

01:30:55.000 --> 01:31:04.000
an uplifted, uh, erosional, very flat-looking erosional surface. in that… in that region.

01:31:04.000 --> 01:31:14.000
So there certainly has been. Um, late Cenozoic uplift in that area, and it certainly would be worth knowing more about.

01:31:14.000 --> 01:31:20.000
in the whole context of the. the foothills, uh, range front fault system.

01:31:20.000 --> 01:31:28.000
Well, Bob, I've been reading a lot of… re-reading and re-reading a lot of your work the last… past years. I'm writing this stuff up.

01:31:28.000 --> 01:31:30.000
Um…

01:31:30.000 --> 01:31:37.000
like I said, the challenges for this kind of work are mainly logistical. We can do the science.

01:31:37.000 --> 01:31:42.000
It's working in these very noisy urban environments.

01:31:42.000 --> 01:31:43.000
Um, we did a… we did great work in LA, uh, especially

01:31:43.000 --> 01:31:47.000
Yeah.

01:31:47.000 --> 01:31:51.000
Uh, using guided ways, you worked with CGS, you know about that, Tim.

01:31:51.000 --> 01:31:55.000
But a lot of that work was in a more, um…

01:31:55.000 --> 01:31:57.000
commercial area?

01:31:57.000 --> 01:32:03.000
And so we could work at night when their cultural noise was lower, and we could make more noise, and not anger everybody.

01:32:03.000 --> 01:32:08.000
In the case of San Carlos, it's all residential. If we wanted to do what we did in LA, we would…

01:32:08.000 --> 01:32:11.000
I mean, we'd have people screaming at us.

01:32:11.000 --> 01:32:13.000
So that's kind of…

01:32:13.000 --> 01:32:16.000
The problem, it's, like I said, this catch-22 is…

01:32:16.000 --> 01:32:19.000
We're doing this work because these faults in an urban setting

01:32:19.000 --> 01:32:22.000
But we can't quite do…

01:32:22.000 --> 01:32:29.000
the really big geophysical experiment to light these things up, like holiday decorations, like we'd like to do.

01:32:29.000 --> 01:32:32.000
Because… we just can't.

01:32:32.000 --> 01:32:34.000
Because it's an urban area.

01:32:34.000 --> 01:32:38.000
We can't play with all of our toys and use all… pull out all our tricks.

01:32:38.000 --> 01:32:40.000
So, we'd have to do this piecemeal, it's just the only way to do it.

01:32:40.000 --> 01:32:45.000
Yeah. Yeah, I understand, Rob. Um, I just encourage you.

01:32:45.000 --> 01:32:46.000
Yeah.

01:32:46.000 --> 01:32:50.000
You know, to the extent that. You have the opportunity again.

01:32:50.000 --> 01:32:51.000
Uh, well, I hope so. Yeah, we'd like to continue. Oh, and I've… I need to…

01:32:51.000 --> 01:32:54.000
2. Yeah. Yeah.

01:32:54.000 --> 01:32:58.000
Before I forget something, uh, this goes back to Christy Rowe.

01:32:58.000 --> 01:33:06.000
I've been in and out of this meeting because I am currently trying to permit about 100 seismometers deployed in the San Ramon-Danville area.

01:33:06.000 --> 01:33:09.000
trying to record aftershocks.

01:33:09.000 --> 01:33:12.000
Anyone in this meeting who lives in San Ramon,

01:33:12.000 --> 01:33:17.000
Danville… where is it? Man at Land Manage Manager.

01:33:17.000 --> 01:33:25.000
If you have anything to do with those areas, can you please contact me? We're looking for help in terms of getting these things cited and permitted.

01:33:25.000 --> 01:33:27.000
So, anyway, that's a plug.

01:33:27.000 --> 01:33:28.000
or current work.

01:33:28.000 --> 01:33:30.000
I think that's a plug we can all…

01:33:30.000 --> 01:33:31.000
And tours.

01:33:31.000 --> 01:33:32.000
Yeah, thank you.

01:33:32.000 --> 01:33:35.000
Fuck with that. Um…

01:33:35.000 --> 01:33:40.000
Well, we're a little beyond our time. I think we should probably wrap things up. So, um…

01:33:40.000 --> 01:33:44.000
Once again, I'd like to thank all the speakers.

01:33:44.000 --> 01:33:53.000
Um, for this excellent, excellent session, and an excellent morning, really. It's… I've been here since we started, and it's just been a great morning, so…

01:33:53.000 --> 01:33:58.000
Um, I'll hand it over to Sarah, I think, right now? Um…

01:33:58.000 --> 01:34:01.000
She has any closing comments before we…

01:34:01.000 --> 01:34:02.000
head out to lunch.

01:34:02.000 --> 01:34:08.000
Thank you, Tim. Thank you, Keith. Thank you to all of our wonderful speakers. That was a fantastic session, and we have

01:34:08.000 --> 01:34:11.000
such a plethora of comments in chat, and

01:34:11.000 --> 01:34:14.000
really lively conversation.

01:34:14.000 --> 01:34:18.000
But, I think we need to feed all of the people, kitties, and other pets that are

01:34:18.000 --> 01:34:34.000
knocking and getting hungry. So, let's take a lunch break now. Um, we're gonna reconvene at 1.15 Pacific time, but it's a Thundertalk session, so if you or any of the people who have Thundertalks coming up,

01:34:34.000 --> 01:34:35.000
Skin makes me cry…

01:34:35.000 --> 01:34:36.000
Please come back at 1PM Pacific so we can get you set up. Otherwise, see everybody else at around 1.15.

01:34:36.000 --> 01:34:40.000
Thank you so much