WEBVTT Kind: captions Language: en-US 00:00:00.930 --> 00:00:04.850 - Hello. I’m Ken Hudson. I’m a graduate student at UCLA 00:00:04.850 --> 00:00:07.608 in the Department of Civil and Environmental Engineering. 00:00:07.608 --> 00:00:10.450 And I’m going to talk to you guys today about the interpolation of 00:00:10.450 --> 00:00:16.066 ground motion intensity measures using kriging at liquefaction sites. 00:00:16.066 --> 00:00:19.900 So it’s important, especially in the Next Generation Liquefaction project 00:00:19.900 --> 00:00:23.400 that I’m involved in, to get accurate estimates 00:00:23.400 --> 00:00:27.853 of ground motion intensity measures at liquefaction sites. 00:00:27.853 --> 00:00:34.640 Now, this is really important because it forms the demand side of the equation 00:00:34.640 --> 00:00:39.040 for models – like, triggering models and manifestation models that we’re 00:00:39.040 --> 00:00:44.650 trying to regress from our data sets that we have in the NGL database. 00:00:44.650 --> 00:00:49.950 So we wanted to come up with a way to more accurately estimate the 00:00:49.950 --> 00:00:55.600 intensity measures at each of these liquefaction case study locations. 00:00:55.600 --> 00:00:59.740 So we’ve come up with the following workflow to do so. 00:00:59.740 --> 00:01:06.020 First we estimate the intensity measures at the recording stations that we have 00:01:06.020 --> 00:01:12.070 using ground motion models. So an earthquake occurs, it records 00:01:12.070 --> 00:01:15.680 at recording stations different intensity measures, and we have those values, 00:01:15.680 --> 00:01:19.470 and now we come back and we compute the estimated 00:01:19.470 --> 00:01:23.460 intensity measures using a ground motion model or multiple 00:01:23.460 --> 00:01:28.550 ground motion models of our choice that are fitting for the region. 00:01:28.550 --> 00:01:33.220 Next we will compute the residuals of those intensity measures based on those 00:01:33.220 --> 00:01:38.700 estimated values and the recorded intensity measures at those stations. 00:01:38.700 --> 00:01:44.579 And the residual, R, total can be broken up into the event term, eta-E, 00:01:44.579 --> 00:01:49.079 and the within-event residual is delta-W, shown in the equation there. 00:01:49.079 --> 00:01:52.090 And that total residual is just the difference between 00:01:52.090 --> 00:01:57.549 the intensity measures in natural log units. 00:01:57.549 --> 00:02:00.689 Next we compute an empirical variogram from that spatial data, 00:02:00.689 --> 00:02:03.729 and we fit a variogram model to it. 00:02:03.729 --> 00:02:07.641 From that variogram model, we can generate a residual krige. 00:02:07.641 --> 00:02:12.857 And the final step, then, is to look at the liquefaction sites that we’re 00:02:12.857 --> 00:02:17.919 interested in, compute the estimate of the intensity measure using the 00:02:17.919 --> 00:02:22.059 same ground motion models we started out with, and then querying that residual 00:02:22.059 --> 00:02:26.629 krige at those liquefaction sites and modifying the estimated 00:02:26.629 --> 00:02:30.480 intensity measures using the krige-queried residual 00:02:30.480 --> 00:02:33.591 to get a final intensity measure estimate. 00:02:33.591 --> 00:02:37.769 So I’m going to go through an example using the Loma Prieta earthquake. 00:02:37.769 --> 00:02:43.909 Here is a satellite image showing the 1989 fault rupture in red. 00:02:43.909 --> 00:02:48.639 The recording stations where we have the intensity measures recorded are 00:02:48.639 --> 00:02:52.059 shown in yellow triangles, and the blue NGL sites where we 00:02:52.059 --> 00:02:54.680 have liquefaction or no liquefaction observations 00:02:54.680 --> 00:02:59.160 along with geotechnical subsurface data are located. 00:02:59.160 --> 00:03:03.959 Those NGL sites often do not correspond with where we have 00:03:03.959 --> 00:03:09.463 recording stations, which is why this interpolation step is so important. 00:03:09.463 --> 00:03:14.430 Here we are showing the recorded intensity measure in blue. 00:03:14.430 --> 00:03:17.731 The estimated intensity measure using the Boore, Stewart, Seyhan and 00:03:17.731 --> 00:03:24.559 Atkinson 2014 ground motion model from the NGA-West2 project in orange. 00:03:24.559 --> 00:03:30.339 And then, in green, we’re adjusting those orange estimates by the computed 00:03:30.339 --> 00:03:35.180 event term, which is taken as the average of the total residuals. 00:03:35.180 --> 00:03:39.599 On the right you can see the within-event residuals plotted 00:03:39.599 --> 00:03:43.842 using that heat map scale at each of the recording stations. 00:03:43.842 --> 00:03:47.439 And so you can see, in the Bay Area, San Francisco, and Oakland, there’s 00:03:47.439 --> 00:03:52.939 very high residuals around 1 or higher. And elsewhere, they’re either around 00:03:52.939 --> 00:03:57.240 zero or negative, depending on the location. 00:03:57.240 --> 00:04:00.590 Next we compute the empirical variogram from that data set, and we 00:04:00.590 --> 00:04:07.595 fit a variogram model, such as this stable variogram, to the data set. 00:04:07.595 --> 00:04:11.279 Then we would need to compute the within-event residual krige 00:04:11.279 --> 00:04:16.489 from that data. What is shown on the left is that krige with the stations 00:04:16.489 --> 00:04:21.090 with the recordings overlaid on top of it, with the same color scale applied. 00:04:21.090 --> 00:04:25.439 And on the right is the same krige with the same color scale showing 00:04:25.439 --> 00:04:29.990 the within-event residuals along with the NGL sites and their 00:04:29.990 --> 00:04:34.713 interpolated residual at each of those locations. 00:04:34.713 --> 00:04:38.360 Then, at each of those locations, we can compute that same 00:04:38.360 --> 00:04:45.470 BSSA intensity measure estimate and, taking the krige’s residual interpolation, 00:04:45.470 --> 00:04:50.729 we can adjust that intensity measure to what is shown on the right in those 00:04:50.729 --> 00:04:55.400 heat maps. The color scale is the same on both the left and the right. 00:04:55.400 --> 00:04:58.842 On the bottom you can see, as a function of distance, 00:04:58.842 --> 00:05:01.134 how the PGA changes. 00:05:01.685 --> 00:05:05.905 - Today I’d like to introduce the application of passive surface method 00:05:05.930 --> 00:05:09.142 using seismic ambient noise to delineate 3D S-wave velocity 00:05:09.142 --> 00:05:14.027 structure at south and east San Francisco Bay Area. 00:05:14.027 --> 00:05:17.680 Left-hand side is the site we carried out active and passive 00:05:17.680 --> 00:05:20.090 surface measurement or [inaudible]. 00:05:20.090 --> 00:05:23.599 We have dispersion curves at these 62 sites. 00:05:23.599 --> 00:05:26.860 Right-hand side is the site we measured H over V. 00:05:26.860 --> 00:05:31.099 We measured H over V at 166 sites. 00:05:32.172 --> 00:05:36.689 To build the 3D velocity model, we used H over V, dispersion curves 00:05:36.689 --> 00:05:40.690 obtained from array measurements. Bedrock depths, H over V relationship 00:05:40.690 --> 00:05:42.430 obtained from array measurement. 00:05:42.430 --> 00:05:47.129 Vs30 information at about 100 sites obtained from active and passive 00:05:47.129 --> 00:05:52.168 surface method downhole or crosshole seismic logging collected by USGS. 00:05:52.168 --> 00:05:55.574 And deep 3D seismic velocity model based on 00:05:55.574 --> 00:05:59.440 geological information compiled by USGS. 00:05:59.440 --> 00:06:02.759 You can take a look all our measurements at our website, 00:06:02.759 --> 00:06:05.767 seisimager.com. Left-hand side is Vs30. 00:06:05.767 --> 00:06:11.926 It includes USGS database as well. So Vs30 is about 150 meters per second 00:06:11.926 --> 00:06:15.590 along the shoreline and increase in the landward direction. 00:06:15.590 --> 00:06:20.860 Vs30 exceeds 300 meters per second at Coyote Hills and on the northeast 00:06:20.860 --> 00:06:26.426 side of the Hayward Fault and the southwest side of San Jose. 00:06:26.426 --> 00:06:29.470 Right-hand side is H over V peak frequency. 00:06:29.470 --> 00:06:31.539 Different color indicates different peak frequency. 00:06:31.539 --> 00:06:36.389 Red to yellow circles indicate low peak frequencies that corresponds 00:06:36.389 --> 00:06:40.330 to deeper bedrock site. And the green to blue circles indicate 00:06:40.330 --> 00:06:45.269 high peak frequencies that corresponds to shallow bedrock sites. 00:06:45.269 --> 00:06:48.964 At the site we carried out all our measurement, we calculated dispersion 00:06:48.964 --> 00:06:54.259 curves and estimated Vs profiles using joint inversion together with H over V. 00:06:54.259 --> 00:06:58.659 We summarized the relationship between H over V peak frequencies 00:06:58.659 --> 00:07:02.360 and bedrock depths obtained from array measurements. 00:07:02.360 --> 00:07:06.219 The site we only measured the H over V, we constructed initial 00:07:06.219 --> 00:07:09.949 velocity model based on Vs30 information, geological information, 00:07:09.949 --> 00:07:13.249 and bedrock depths estimated by H over V peak frequencies 00:07:13.249 --> 00:07:17.971 then applied inversion to estimate Vs profiles. 00:07:19.201 --> 00:07:24.210 This figure summarizes relationship between H over V peak frequencies 00:07:24.210 --> 00:07:30.650 and shallow – 760 meters per second, and deep – 2,500 meters per second 00:07:30.650 --> 00:07:33.754 bedrock depths as obtained from this study. 00:07:33.754 --> 00:07:38.009 It is clear that both shallow and deep bedrock depth increase 00:07:38.009 --> 00:07:41.879 as frequency decreases. The regression line, broken lines 00:07:41.879 --> 00:07:46.870 for two bedrock depths are used to generate the initial 1D profiles of 00:07:46.870 --> 00:07:52.839 the inversion at sites only H over V measurement was performed. 00:07:54.169 --> 00:07:57.759 This figure compares Vs profiles obtained from this study with the 00:07:57.784 --> 00:08:02.473 3D velocity model [inaudible] geological information compiled by USGS 00:08:02.473 --> 00:08:06.930 At the South Bay, depths to layer with Vs of 2,000 meter per second 00:08:06.930 --> 00:08:12.559 was approximately 1,900 meter and 500 meter at Cupertino and Alviso, 00:08:12.559 --> 00:08:17.238 respectively. At the East Bay, depths to a layer with Vs of 00:08:17.238 --> 00:08:21.250 2,000 meter per second were approximately 600 meter and 00:08:21.250 --> 00:08:26.452 900 meter at Fremont and San Leandro, respectively. 00:08:26.452 --> 00:08:29.870 We can say that the Vs profiles obtained from H over V and 00:08:29.870 --> 00:08:32.409 other measurement were reasonably consistent with 00:08:32.409 --> 00:08:37.053 the 3D velocity model based on geological information. 00:08:37.053 --> 00:08:43.440 We combined all 1D Vs profiles and interpret to a 3D velocity model. 00:08:43.440 --> 00:08:48.410 Left-hand side is interpolated Vs30. Here is the Coyote Hills 00:08:48.410 --> 00:08:53.810 and Hayward Fault. It ranges 150 to 500 meters per second 00:08:53.810 --> 00:08:59.512 and lower at shoreline to middle of South Bay and higher at mountainside. 00:08:59.512 --> 00:09:06.120 Right-hand side is the shallow bedrock depths on top of 750 meters per second. 00:09:06.120 --> 00:09:09.284 Here is the Coyote Hills and Hayward Fault. 00:09:09.284 --> 00:09:14.670 Depths to the shallow bedrock ranges 20 to 400 meter, and it is 00:09:14.670 --> 00:09:19.274 generally deeper at South Bay compared with East Bay. 00:09:19.274 --> 00:09:24.470 At the South Bay, the bedrock is deeper at Cupertino and Evergreen Basins. 00:09:24.470 --> 00:09:29.202 It is shallower around the Silver Creek Fault to Coyote Hills. 00:09:30.664 --> 00:09:34.211 Left-hand side is Vs at 400-meter depth. 00:09:34.211 --> 00:09:37.438 Here is Coyote Hills and Hayward Fault. 00:09:37.438 --> 00:09:42.760 We can see Vs is generally lower at South Bay compared with East Bay. 00:09:42.760 --> 00:09:48.570 Left-hand side is Vs at 700-meter depth. Here is Coyote Hills and 00:09:48.570 --> 00:09:53.630 Hayward Fault. At South Bay, Vs is relatively higher at middle 00:09:53.630 --> 00:09:59.539 of valley from downtown San Jose to San Jose Airport and Alviso. 00:09:59.539 --> 00:10:03.120 The high-velocity reached in the South Bay appears prior to the 00:10:03.120 --> 00:10:07.810 Silver Creek Fault and may continue northwest to Coyote Hills. 00:10:08.941 --> 00:10:12.420 Now I take cross-sections at South Bay. 00:10:12.420 --> 00:10:15.940 Here is a cross-section from Menlo Park to San Jose. 00:10:15.940 --> 00:10:20.149 The shallow bedrock is clearly shallower at Alviso and deeper 00:10:20.149 --> 00:10:23.199 at Evergreen Basin. Here is a cross-section 00:10:23.199 --> 00:10:26.990 from Cupertino to San Jose. The shallow bedrock is clearly 00:10:26.990 --> 00:10:31.783 shallower at SJC and deeper at Evergreen Basin. 00:10:32.791 --> 00:10:36.236 Here is the conclusions. Note that the 3D Vs model 00:10:36.236 --> 00:10:39.120 is preliminary model. More geological measurements 00:10:39.120 --> 00:10:43.216 are needed to delineate the basin structure in greater detail. 00:10:43.216 --> 00:10:44.930 Thank you very much. 00:10:45.263 --> 00:10:48.750 - I’d like to present to you the Reno ShakeOut scenario, 00:10:48.750 --> 00:10:56.600 which was published in BSSA by Eckert and others back in 2021. 00:10:56.600 --> 00:10:58.930 This scenario predicts ergodic potential ground shaking 00:10:58.930 --> 00:11:03.270 for one magnitude 6 event in Reno. 00:11:03.270 --> 00:11:07.339 And incorporated into the geologic model that it uses are 00:11:07.339 --> 00:11:11.620 gravity-derived basin thicknesses, which are mostly pretty smooth 00:11:11.620 --> 00:11:15.810 and less than 1 kilometer in thickness. 00:11:15.810 --> 00:11:22.089 The shear velocity within the basin is averaged to a one-dimensional model 00:11:22.089 --> 00:11:27.029 between the surface and the basin floor. And that gives the basins themselves 00:11:27.029 --> 00:11:34.745 less lateral velocity variability than was measured by Pancha and others in 2017. 00:11:34.745 --> 00:11:38.980 However, above 30 meters – within 30 meters of the surface, 00:11:38.980 --> 00:11:44.150 there is full geotechnical lateral velocity variation as measured, 00:11:44.150 --> 00:11:48.240 which over small distances, varies by a factor of 2. 00:11:48.240 --> 00:11:53.089 And that’s from Scott et al. in 2004. 00:11:53.089 --> 00:12:02.522 This model, we fed it into an SW4 computation with help from Pitarka 00:12:02.522 --> 00:12:09.350 and Graves’ stochastic source model. And we did that computation up to 00:12:09.350 --> 00:12:14.863 3 hertz, so that required a 30-kilometer- wide grid with 40-meter sampling. 00:12:14.863 --> 00:12:20.550 And it took 20,000 core-hours on the Lawrence Berkeley Lab’s Cori machine. 00:12:20.550 --> 00:12:25.819 Now, the outcome of this model is that the whole urban basin gets severe 00:12:25.819 --> 00:12:34.754 shaking. And that’s at a level of greater than 4/10 of a meter per second PGV. 00:12:34.754 --> 00:12:40.230 Even though the basins are thin and less than 1 kilometer deep, there are 00:12:40.230 --> 00:12:45.589 some spots of extreme ground shaking of greater than 1.5 meters per second 00:12:45.589 --> 00:12:53.560 PGV over very small areas of less than 0.1 square kilometer. 00:12:53.560 --> 00:12:57.139 And their location is very hard to predict. 00:12:57.139 --> 00:13:02.319 The predicted shaking and amplification at this 3-hertz frequency is thus 00:13:02.319 --> 00:13:08.800 quite peaky and can vary by a factor of 2 across less than 1-kilometer distances, 00:13:08.800 --> 00:13:12.314 even when you’re not near the basin edge. 00:13:12.314 --> 00:13:16.279 More in-basin scattering should – if we could include that in the model, 00:13:16.279 --> 00:13:20.980 should dampen the peaks and extend the durations. 00:13:20.980 --> 00:13:25.810 And that’s important because we’re only achieving 30-second 00:13:25.810 --> 00:13:32.779 model durations, whereas we have 60-second shaking durations recorded. 00:13:33.591 --> 00:13:38.569 So we started modeling some additional Reno quake scenarios for a nonergodic 00:13:38.569 --> 00:13:45.591 view, and that plus the improved in-basin scattering will lead us to 00:13:45.591 --> 00:13:51.339 some additional results pretty soon. Thanks for your attention. 00:13:53.896 --> 00:13:56.959 - Hello, everyone. I would like to share with you briefly 00:13:56.959 --> 00:14:01.459 some aspects of a five-year center operations proposal to NSF that 00:14:01.459 --> 00:14:06.420 SCEC is developing on the coupled evolution of earthquakes, faults, 00:14:06.420 --> 00:14:11.069 and geohazard in the San Andreas Fault System. 00:14:11.069 --> 00:14:15.819 Using the entire San Andreas system as a natural laboratory of the next center 00:14:15.819 --> 00:14:23.129 will include the appropriate boundaries for quantitative modeling of earthquake 00:14:23.129 --> 00:14:28.089 processes in the system, including sub-parts of the system, 00:14:28.089 --> 00:14:32.010 with increasing types of faults and slip modes and with increased 00:14:32.010 --> 00:14:36.190 populations that can benefit directly from the research. 00:14:36.190 --> 00:14:39.279 Analyzing earthquake faults and geohazard is coupled dynamical system 00:14:39.279 --> 00:14:48.230 which is a major part of the proposal. We’ll provide quantitative 00:14:48.230 --> 00:14:53.720 understanding of relations between diverse outputs that are generated 00:14:53.720 --> 00:14:59.400 simultaneously in the crust, such as evolving seismicity, ground motion, 00:14:59.400 --> 00:15:06.089 fault network configuration, evolving surface strain rates, and evolving 00:15:06.089 --> 00:15:12.399 dynamic topography near faults. Using such diverse outputs for testing 00:15:12.399 --> 00:15:16.172 and further development of models will reduce the 00:15:16.172 --> 00:15:23.589 non-uniqueness of model results and will lead to improved hazard estimates. 00:15:23.589 --> 00:15:28.810 The science plan of the proposal has four major research thrusts 00:15:28.810 --> 00:15:34.152 with 12 topical elements, shown here on the left. 00:15:34.192 --> 00:15:40.769 Thrust A aims to close critical data gaps, such as those associated with near-fault 00:15:40.769 --> 00:15:47.560 regions in the very top crust and then synthesize the results in multi-scale 00:15:47.560 --> 00:15:52.166 community models which will include northern California. 00:15:52.166 --> 00:15:58.130 The second thrust is to develop rheologies that bridge the multitude of scales 00:15:58.130 --> 00:16:04.346 and conditions of earthquake-related formation. This is two parts. 00:16:04.346 --> 00:16:08.900 One is to develop effective constitutive laws for brittle deformation of fault 00:16:08.900 --> 00:16:13.250 zone regions. And the second one is to develop effective constitutive laws 00:16:13.250 --> 00:16:17.096 for long-term large-scale regional deformation. 00:16:17.096 --> 00:16:22.250 Thrust C is to develop advanced virtual modeling frameworks that will use 00:16:22.250 --> 00:16:29.269 the constitutive laws and the data sets to model to provide quantitative 00:16:29.269 --> 00:16:33.000 predictive information on several phenomena. 00:16:33.000 --> 00:16:37.760 So one virtual modeling framework would be to model tectonic 00:16:37.760 --> 00:16:42.589 deformation. Another one is to model coupled evolution of 00:16:42.589 --> 00:16:46.879 earthquakes and faults. This is – will be next-generation 00:16:46.879 --> 00:16:52.478 earthquake simulator that will include evolution of fault structures during the 00:16:52.478 --> 00:16:56.720 occurrence of earthquakes as well as with the ongoing tectonic loading. 00:16:56.720 --> 00:17:00.209 And the third virtual modeling framework aims to improve estimate 00:17:00.209 --> 00:17:07.380 of seismic hazard in California. This is essentially next UCERF. 00:17:07.380 --> 00:17:12.920 And here SCEC involvement will be primarily science contributions 00:17:12.920 --> 00:17:21.483 that can aid future UCERF simulations that will be done by the USGS. 00:17:21.483 --> 00:17:25.580 The last thrust of activities is to improve the predictive understanding 00:17:25.580 --> 00:17:30.480 of seismicity. This has several components including improved 00:17:30.480 --> 00:17:34.762 forecasting of seismicity that can go beyond ETAS – 00:17:34.762 --> 00:17:39.840 the next generation of ETAS. Another topic is tracking preparation 00:17:39.840 --> 00:17:44.440 processes of large earthquakes that might lead to development of 00:17:44.440 --> 00:17:50.310 hierarchical search for evolutionary behavior before large earthquakes. 00:17:50.310 --> 00:17:55.710 And the last topic is associated with induced seismicity. 00:17:55.710 --> 00:18:01.930 And here the focus will be on performing crustal-scale experiments 00:18:01.930 --> 00:18:04.760 that can help understanding earthquake physics and 00:18:04.760 --> 00:18:07.510 test time-dependent forecasting. 00:18:07.510 --> 00:18:14.090 In addition to the system science, there are four other major activities in the 00:18:14.090 --> 00:18:21.567 proposal that will – that are listed here. Number two is develop state-of-the-art 00:18:21.567 --> 00:18:25.600 community modeling framework that will allow the science to take place. 00:18:25.600 --> 00:18:30.870 Then we wish to develop impactful workforce development. 00:18:30.870 --> 00:18:35.120 We want to develop multifaceted community engagement both within 00:18:35.120 --> 00:18:41.858 our own community between scientists as well as between scientists in 00:18:41.858 --> 00:18:45.970 various sectors of the public. And the last part is effective science 00:18:45.970 --> 00:18:50.450 planning and coordination. We plan to increase activities 00:18:50.450 --> 00:18:54.330 in northern California on all of these fronts in collaboration 00:18:54.330 --> 00:18:59.642 with the USGS, CGS, universities, and industry. 00:18:59.642 --> 00:19:07.513 And I thank you for listening and will be happy to have follow-up discussions. 00:19:09.517 --> 00:19:13.050 - Hello. Welcome to a short presentation on the SCEC Statewide Community 00:19:13.050 --> 00:19:17.117 Fault Model and automated earthquake-fault associations. 00:19:17.117 --> 00:19:23.609 Let me briefly introduce you to the SCFM model in an overview. 00:19:23.609 --> 00:19:27.520 What you can see here is a perspective view of the model 00:19:27.520 --> 00:19:32.120 and the associated map. The model is a comprehensive 00:19:32.120 --> 00:19:37.020 3D model of all faults deemed capable of generating destructive 00:19:37.020 --> 00:19:43.990 earthquakes in the state. That’s the target. Currently it consists of about 00:19:43.990 --> 00:19:51.250 450 faults in southern California and about 130 faults in northern California. 00:19:51.250 --> 00:19:55.070 The tradition, for historic reasons, the model in southern California 00:19:55.070 --> 00:19:58.720 is more mature and much longer developed. 00:19:58.720 --> 00:20:04.900 The faults are geometric objects and are available as 3D triangulated 00:20:04.900 --> 00:20:12.070 meshes from which also a fault trace shape file was derived, 00:20:12.070 --> 00:20:18.541 which is available for GS purposes [inaudible] at that link. 00:20:18.541 --> 00:20:25.520 Moving on to how this large model is organized and divided up into 00:20:25.520 --> 00:20:32.304 geographic flood areas to manage a large model like this, 00:20:32.304 --> 00:20:36.030 shown in different colors in this perspective view. 00:20:36.030 --> 00:20:41.590 Each fault is constructed from various geologic and geophysical 00:20:41.590 --> 00:20:47.146 constraints as they are available. For very well-constrained faults, 00:20:47.146 --> 00:20:52.384 we’ll have subsurface data from wells and, in some cases, 00:20:52.384 --> 00:20:58.705 seismic reflection surveys, mostly in the [inaudible] basins and offshore. 00:20:58.705 --> 00:21:02.126 For others, we will use trace maps from 00:21:02.150 --> 00:21:08.851 geologic mapping and cross-sections – conceptual cross-sections even if this is 00:21:08.851 --> 00:21:15.156 the best-constrained we have. The model is regularly reviewed in large evaluation 00:21:15.156 --> 00:21:23.063 efforts. And these reviews can then particularly pay attention to those faults 00:21:23.063 --> 00:21:29.240 for which multiple different alternative representations are provided 00:21:29.240 --> 00:21:34.210 in the model, which are ranked. And, in fact, we are currently inviting 00:21:34.210 --> 00:21:38.260 experts to go through the process to evaluate the southern California 00:21:38.260 --> 00:21:44.680 part of the model, the CFM, after we do that. It’s a peer review process. 00:21:44.680 --> 00:21:49.870 It’s designed to make it easy for invited experts to go through the 00:21:49.870 --> 00:21:54.100 faults and look at them. We use special tools developed for this purpose. 00:21:54.100 --> 00:21:57.376 A map viewer which has a map and 3D option. 00:21:57.376 --> 00:22:06.030 We use a web-based survey tool to show screenshots and allow ranking as 00:22:06.030 --> 00:22:11.928 well as provide more in-depth source data for each fault to be evaluated. 00:22:11.928 --> 00:22:15.270 This will focus on a more limited number of faults which have these 00:22:15.270 --> 00:22:16.960 more meaningful alternative choices 00:22:16.960 --> 00:22:20.820 of representation based on past experience [inaudible]. 00:22:20.820 --> 00:22:24.830 The results then will be collated and made available in the 00:22:24.830 --> 00:22:28.950 preferred community model in the next release. 00:22:28.950 --> 00:22:33.220 For the northern California portion of the model, we have 130 faults organized 00:22:33.220 --> 00:22:40.330 into these six fault areas shown in colors in the perspective view. 00:22:40.330 --> 00:22:44.978 The portion of the state that’s the – state border here that’s offshore that’s – 00:22:44.978 --> 00:22:48.626 the large Cascadia subduction zone, for example, the San Andreas Fault, 00:22:48.659 --> 00:22:54.770 give you a sense of the kind of updates we go through, I’ll show the last ones, 00:22:54.770 --> 00:23:00.400 which are a result of a early review focusing on the offshore portion here. 00:23:00.400 --> 00:23:05.220 All these faults which were added or improved in the situation from [inaudible]. 00:23:05.220 --> 00:23:10.050 Finally, let me briefly mention one use of the model, which is 00:23:10.050 --> 00:23:16.700 an automated way to assign a source fault to an earthquake when it happens 00:23:16.700 --> 00:23:21.500 in an objective automated way. For this, we developed a statistical 00:23:21.500 --> 00:23:28.959 model trained from a training data set, which we have known associations. 00:23:28.959 --> 00:23:33.160 This map shows that application of the model to a catalog. 00:23:33.160 --> 00:23:36.370 The earthquakes are colored according to the fault to which 00:23:36.370 --> 00:23:40.720 they were associated. It’s currently operationally deployed, 00:23:40.720 --> 00:23:47.030 meaning that there’s a system which computes the probability of association 00:23:47.030 --> 00:23:51.670 right after an earthquake occurs and it’s located. 00:23:51.670 --> 00:23:55.768 You can actually sign up for a notification service, 00:23:55.768 --> 00:24:01.550 which emails these notes with the earthquake. That’s how it looks. 00:24:01.550 --> 00:24:06.232 And then a list of faults and their probabilities of association. 00:24:06.232 --> 00:24:10.360 This is an example from last week from a fault on the San Jacinto system. 00:24:10.360 --> 00:24:11.900 Thank you for your attention. 00:24:11.900 --> 00:24:14.510 - This is Janiele Maffei, chief mitigation officer at the 00:24:14.510 --> 00:24:17.730 California Earthquake Authority. The CEA is not an agency. 00:24:17.730 --> 00:24:22.510 We are an instrumentality of the state, created after the 1994 Northridge 00:24:22.510 --> 00:24:26.260 earthquake when insurance companies stopped writing homeowner policies 00:24:26.260 --> 00:24:28.410 because California law required them to offer 00:24:28.410 --> 00:24:31.337 earthquake insurance to their policyholders. 00:24:31.337 --> 00:24:34.110 Most of you are familiar with our mitigation grant program, 00:24:34.110 --> 00:24:39.140 Earthquake, Brace, and Bolt, or EBB. EBB has provided up to $3,000 00:24:39.140 --> 00:24:44.170 to over 16,000 California homeowners to retrofit their older homes. 00:24:44.170 --> 00:24:47.410 Our most recent registration period also offered supplementary grants 00:24:47.410 --> 00:24:50.340 to low-income homeowners. We expect to be able to open 00:24:50.340 --> 00:24:55.210 a new registration period in the first half of 2022. 00:24:55.210 --> 00:24:57.930 The CEA sponsors research that investigates both earthquake 00:24:57.930 --> 00:25:01.590 hazards and vulnerabilities. The seismic vulnerability targeted 00:25:01.590 --> 00:25:05.340 in the EBB program is the older cripple wall house that has inadequate 00:25:05.340 --> 00:25:08.097 sill plate anchorage and bracing in the crawl space. 00:25:08.097 --> 00:25:12.030 Houses like this one damaged in the 2014 Napa earthquake were 00:25:12.030 --> 00:25:15.840 obviously not suitable for occupancy. The typical repair time for these 00:25:15.840 --> 00:25:20.079 houses after the Napa earthquake was two years. 00:25:20.079 --> 00:25:25.100 The CEA sponsored a peer research project completed in 2019 that 00:25:25.100 --> 00:25:29.090 confirmed seismic retrofits of cripple wall houses are effective. 00:25:29.090 --> 00:25:33.020 The project quantified the savings of the cripple wall retrofit for scenario 00:25:33.020 --> 00:25:36.530 earthquakes around California. This graphic shows the benefits 00:25:36.530 --> 00:25:40.010 of retrofit for the two-story wood-sided house in San Francisco 00:25:40.010 --> 00:25:42.370 after a magnitude 7.0 earthquake. 00:25:42.370 --> 00:25:47.320 The $200,000 savings indicated by the red pin is for a 2,400-square-foot 00:25:47.320 --> 00:25:51.000 house with a $200-per-square-foot replacement cost. 00:25:51.000 --> 00:25:54.470 Of course, the actual replacement cost for houses in San Francisco 00:25:54.470 --> 00:25:58.980 is upward of $400 per square foot, making the actual average savings 00:25:58.980 --> 00:26:02.457 closer to $400,000. 00:26:02.457 --> 00:26:06.510 The CEA research department has also been conducting an in-house research 00:26:06.510 --> 00:26:11.472 project to evaluate the hazard models that are used to establish insurance rates. 00:26:11.472 --> 00:26:14.880 The CEA was created by the California legislature and is governed 00:26:14.880 --> 00:26:18.470 by the California Insurance Code. The code requires that insurance 00:26:18.470 --> 00:26:23.730 rates be established using best available science. The USGS and CGS are 00:26:23.730 --> 00:26:29.600 specifically identified as experts providing this best available science. 00:26:29.600 --> 00:26:32.380 The current estimates of future earthquake ground motion hazards 00:26:32.380 --> 00:26:36.380 in California presented in the USGS probabilistic seismic hazard maps of 00:26:36.380 --> 00:26:41.660 California are based on two models. One, UCERF3, time-independent 00:26:41.660 --> 00:26:45.190 model for earthquake – earthquake magnitudes, locations, and rates 00:26:45.190 --> 00:26:48.920 or probabilities. And two, NGA-West2 model 00:26:48.920 --> 00:26:52.260 for estimating future ground motion levels and their uncertainties. 00:26:52.260 --> 00:26:56.280 The implementation of the UCERF3 and NGA-West2 00:26:56.280 --> 00:26:59.070 also demanded and received additional information or judgments 00:26:59.070 --> 00:27:03.405 on the part of the USGS implementation team. 00:27:03.405 --> 00:27:06.950 UCERF3 had an impact on insurance rates, causing significant increases 00:27:06.950 --> 00:27:09.558 in premiums for many California homeowners. 00:27:09.558 --> 00:27:13.360 Two elements with the largest impacts were the inclusion of multi-segment 00:27:13.360 --> 00:27:16.761 and multi-fault ruptures. As a direct result of UCERF3, 00:27:16.761 --> 00:27:20.340 the CEA created the Best Available Science Committee, or BASC. 00:27:20.340 --> 00:27:24.300 BASC is comprised of the CEA chief mitigation officer, chief risk and 00:27:24.300 --> 00:27:29.000 actuarial officer, chief catastrophe response and resiliency officer, 00:27:29.000 --> 00:27:33.150 senior science adviser, and director of re-insurance and risk transfer. 00:27:33.150 --> 00:27:37.790 The first goal of BASC was to conduct an in-depth investigation of the UCERF 00:27:37.790 --> 00:27:41.950 time-independent model features in light of the information and knowledge 00:27:41.950 --> 00:27:45.280 which has been produced since the implementation of the model 00:27:45.280 --> 00:27:48.860 and release of the seismic hazard maps for California. 00:27:48.860 --> 00:27:51.660 The second goal was to explore and address issues related to 00:27:51.660 --> 00:27:56.350 the USGS implementation of UCERF3 and NGA-West2 models 00:27:56.350 --> 00:28:01.704 which resulted in the probabilistic seismic hazard maps of California. 00:28:01.732 --> 00:28:05.315 As of the December 2021 CEA board meeting, BASC completed 00:28:05.340 --> 00:28:09.190 its initial investigation, having conducted 13 interviews with 00:28:09.190 --> 00:28:12.460 scientists and researchers involved with the UCERF3 project questioning 00:28:12.460 --> 00:28:16.700 specific issues with UCERF3. BASC also interviewed various 00:28:16.700 --> 00:28:19.830 representatives from each of the three modeling companies – CoreLogic, 00:28:19.830 --> 00:28:24.450 RMS, and AIR, that are under contract with the CEA to implement the hazard 00:28:24.450 --> 00:28:27.790 model developed in UCERF3 into models that provide 00:28:27.790 --> 00:28:31.420 information used to establish earthquake insurance rates 00:28:31.420 --> 00:28:35.130 and secure re-insurance and other financial products. 00:28:35.130 --> 00:28:39.030 Based on this effort, BASC has ruled out the possibility of making short-term 00:28:39.030 --> 00:28:44.691 or immediate modifications to the CEA’s view of best-available science. 00:28:44.691 --> 00:28:47.970 BASC is currently working with the California Geological Survey and the 00:28:47.970 --> 00:28:52.580 United States Geological Survey to identify ways in which the CEA and 00:28:52.580 --> 00:28:55.390 other members of the risk modeling community can enhance their 00:28:55.390 --> 00:28:59.140 participation in the development of the ongoing hazard model. 00:28:59.140 --> 00:29:04.000 BASC has also determined that USGS is addressing the issues identified as 00:29:04.000 --> 00:29:08.330 requiring further study in their ongoing work on the next model, UCERF4. 00:29:08.330 --> 00:29:13.100 Additionally, BASC is reviewing the implementation and assumptions 00:29:13.100 --> 00:29:16.570 underlying the demand-search component of the catastrophe loss 00:29:16.570 --> 00:29:20.090 models. BASC will continue as a CEA committee reporting 00:29:20.090 --> 00:29:23.065 frequently to a larger CEA modeling committee. 00:29:23.065 --> 00:29:25.970 We look forward to this collaborative effort and would be happy to 00:29:25.970 --> 00:29:29.470 meet with researchers studying segmentation and the creeping section 00:29:29.470 --> 00:29:31.690 of the San Andreas Fault. Thank you.