San Diego Regional Chapter

Honoring the Lifetime Achievements and Contributions of Professor Kenji Ishihara

September 10th & 11th, 2026
University of California, San Diego
Franklin Antonio Hall 1301

Join us for the 8th Kenji Ishihara Colloquium Series on Earthquake Engineering, hosted by the EERI UCSD Student and San Diego Regional Chapters. This year’s colloquium will consist of a one-day short course on September 9th about Advanced Tools for Site Response Analysis featuring Professor Ellen Rathje, Dr. Albert Kottke, and Professor Adrian Rodriguez-Marek, followed by a lineup of notable speakers on September 10th & 11th covering topics in tribute to the late Professor Kenji Ishihara.

Celebrate the life, legacy, and contributions of Dr. Kenji Ishihara (April 16, 1934 – December 26, 2025) as we honor him at this year’s colloquium series. Over the course of two days, distinguished academics and professionals from around the world will present on topics reflective of Dr. Ishihara’s work and expertise, such as seismic site response, seismic isolation, liquefaction effects, structural responses in urban settings, analysis of recent major earthquakes, and more. We will also take a look at notable moments from Dr. Ishihara’s career, recognizing his decades-long impacts on the field of earthquake geotechnical engineering and soil mechanics.

Click the images to the above-right and below to view the event flyer and announcement slides, respectively.

PROGRAM

Thursday, September 10th

Session 1 - Moderator: TBD

Session 2 - Moderator: TBD

Friday, September 11th

Session 3 - Moderator: TBD

Session 4 - Moderator: TBD

VENUE
University of California, San Diego
Franklin Antonio Hall 1301
3180 Voigt Drive
La Jolla, CA 92093

REGISTRATION
Click here to register for the colloquium. Early bird registration will be available through 8/10/2026. You will be prompted to register into your my.eeri.org account when you click the blue “Register to Attend” button on the registration page. If you do not have an EERI account, use the “Sign Up” button to create one. We strongly recommend each registrant create an individual EERI account to ensure all communications—including receipts and PDH credits—are received. Accepted payment methods are credit card (MasterCard, Visa, Discover) and ACH. If you need to pay by wire transfer, please contact eeri@eeri.org.

LODGING
Click here for a list of hotels near UCSD.

PARKING
For $8 per day, conference parking permits are available in advance through UCSD’s Parking Portal website, which you can access by clicking here. In order to purchase a parking permit, you will need to create an account. When you click on the aforementioned link, it should show a “Guest User Registration” form. Otherwise, click on “SIGNUP” in the upper right corner of the webpage. Once you fill out the form and create an account, follow the prompts to purchase your conference parking permit for the days you will be attending the colloquium.

You can also pay for parking through the ParkMobile app or website the day(s)-of the colloquium series. More information can be found here.

There are two structures available for parking near Franklin Antonio Hall: Hopkins and Pangea. The closest parking structure to the venue is Hopkins Parking Structure (view here or here), located on Voigt Dr. off of Hopkins Dr. If Hopkins is full, please go to Pangea Parking Structure (view here or here), located on Pangea Dr. off of N. Torrey Pines Rd. You may only park in B-spaces with your pre-purchased conference parking permit.

Click image below to see the parking structures and venue highlighted (from https://maps.ucsd.edu/map/default.htm):

Click image below to see the parking structures and venue highlighted on Google Maps (from https://act.ucsd.edu/maps/):

SPEAKERS AND ABSTRACTS

Dr. Jonathan Bray, Ph.D., P.E., NAE
Faculty Chair, Earthquake Engineering Excellence | University of California, Berkeley
Prof. Ishihara’s Contributions to the Evaluation of Liquefaction Effects

Abstract: N/A

Bio: Jonathan Bray, Ph.D., P.E., NAE is the Faculty Chair in Earthquake Engineering Excellence at the University of California, Berkeley. Dr. Bray is a registered professional civil engineer and has served as a consultant on important engineering projects and peer review panels. He has authored more than 500 research publications on topics that include liquefaction and its effects on structures, seismic performance of dams, earthquake ground motions and site effects, and earthquake fault rupture. He created and led the Geotechnical Extreme Events Reconnaissance (GEER) Association. Dr. Bray is a member of the U.S. National Academy of Engineering and has received honors such as the Seed Medal, Terzaghi Award, Ishihara Lecture, Peck Award, Middlebrooks Award, and Huber Research Prize.

Dr. Trevor Carey, Ph.D.
Assistant Professor, Civil and Mineral Engineering | University of Toronto
Beyond Triggering: Ground Motion Characteristics Governing Liquefaction-Induced Strain Accumulation During Crustal and Subduction Earthquakes

Abstract: Liquefaction assessments have traditionally focused on triggering; however, engineering performance is often governed by the accumulation of strain and deformation following triggering. Understanding these post-triggering processes remains challenging because ground motions with similar cyclic shear stress demand can produce substantially different deformation responses. This presentation examines liquefaction-induced strain accumulation using a series of recent dynamic centrifuge experiments subjected to recorded crustal and subduction earthquake ground motions. The testing program spans a range of ground motion durations, intensity measures, and waveform characteristics representative of different earthquake source types. Measurements of acceleration, excess pore water pressure, and deformation were collected throughout the soil profile using multiple instrumentation approaches, allowing direct linkages between ground motion characteristics, liquefaction response, and strain accumulation. Experimental results show that deformation is influenced not only by triggering, but also by the duration, intensity, and temporal characteristics of shaking. Comparisons between crustal and subduction motions highlight important differences in post-triggering response that are not captured by conventional triggering-based approaches. The findings provide new insights into the ground motion characteristics governing liquefaction-induced strain accumulation and support the development of improved procedures for evaluating liquefaction-induced deformation hazards during future earthquakes.

Bio: Trevor Carey is an assistant professor in the department of Civil and Mineral Engineering at the University of Toronto. He has degrees in Geotechnical Engineering (UC Davis, Ph.D. 2019), Structural Engineering (Oregon State University (OSU), M.S. 2014), and Civil Engineering (OSU, B.S. 2012). His interests and specialty are in geotechnical earthquake engineering, soil dynamics, and infrastructure performance from extreme events. He uses a multiscale approach leveraging case histories, experimental methods, numerical tools, and advanced data analytics to improve the resiliency of the built environment against the impacts of earthquakes and other extreme events. He was awarded the I.M. Idriss award for Excellence in Geotechnical Engineering from UC Davis and was selected as a graduate student fellow in earthquake hazard reduction by the Earthquake Engineering Research Institute.

Dr. Shideh Dashti, Ph.D.
Associate Chair for Administration, Department of Civil, Environmental and Architectural Engineering | University of Colorado Boulder
Mitigation of Seismic Liquefaction in Urban Settings and Stratigraphically Variable Sites

Abstract: The existing engineering methodologies for mitigation of seismic liquefaction rely on free-field triggering in uniformly layered granular soil deposits. These methods often do not evaluate performance, and they routinely ignore cross-layer interactions in realistically stratified deposits as well as soil-structure interaction (SSI) and structure-soil-structure interaction (SSSI) in urban settings. In this presentation, through an experimental-numerical-statistical study, we show that these methods are unreliable, jeopardizing our ability to assess and mitigate liquefaction vulnerability of our sites and structures. We performed fully-coupled, 3D, dynamic finite element analyses of free-field site response, seismic SSI, and SSSI in OpenSees. These simulations were calibrated and validated with element and centrifuge experiments. The influence of stratigraphic variability on mitigation efficacy is shown to be significant in terms of foundation settlement, tilt, spectral accelerations, and flexural drift. Physics-informed machine learning (ML) is subsequently used to identify the key predictors and predictive models for free-field ejecta potential and mitigated/non-mitigated ratio of isolated foundation settlement. The performance of mitigation is also shown to depend strongly on the dynamic properties of the neighboring structures and spacing in urban settings. Although settlements are generally reduced satisfactorily, the combination of SSSI, mitigation, and interlayering typically amplify asymmetrical deformations below the foundations (hence, permanent tilt) as well as column strains, particularly for an unmitigated neighbor. The results indicate that ground improvement must be designed with extreme care in urban settings and stratigraphically variable profiles.

Bio: Shideh Dashti is a Professor in Geotechnical Engineering and Geomechanics at the University of Colorado Boulder (CU) and the Associate Chair for Administration in the Department of Civil, Environmental and Architectural Engineering. Shideh obtained her undergraduate degree at Cornell University in 2004 and graduate degrees at the University of California, Berkeley in 2009. She worked briefly with ARUP and Bechtel on several engineering projects in the U.S. and around the world, spanning seismic design of underground structures, foundations, and slopes. Her research team at CU studies: the interactions and interdependencies among infrastructure systems during earthquakes and climatic extremes; seismic performance of underground structures; triggering, consequence, and mitigation of the liquefaction hazard at local and regional scales; impact of compound climatic-seismic hazards on geotechnical infrastructure; application of physics-informed machine learning to geotechnical earthquake engineering; and the intersection of resilience, environmental sustainability, and justice. She is the recipient of the 2018 Arthur Casagrande Award and the 2021 Walter Huber Civil Engineering Research Prize from ASCE as well as the 2025 Distinguished Lecture Award from EERI, among other recognitions.

Dr. Ahmed Elgamal, Ph.D.
Distinguished Professor, Department of Structural Engineering | University of California, San Diego
Seismic Response of Ground and Ground-Structure Systems: Insights from Computational Simulation

Abstract: Recorded earthquake motions provide key insights into the seismic response of ground and ground-structure systems. Calibrated by such records, computational frameworks are developed to explore the associated Ground response and Soil-Structure-Interaction (SSI) mechanisms. Using these frameworks, large ground-foundation-structure configurations are modeled, to highlight the importance and significance of system, and to conduct sustainability and resilience assessments.

Bio: Ahmed Elgamal holds the title of Distinguished Professor at the University of California, San Diego (UCSD). Earlier, he served as the UCSD School of Engineering Associate Dean for Faculty Affairs, and he chaired the Department of Structural Engineering. He received his PhD in 1985 from Princeton University. In 1997, he joined UCSD after a Post-doctoral appointment at the California Institute of Technology (CalTech), and Faculty positions at RPI and Columbia University in New York City.

His areas of research interest include large-scale soil-structure experimental and computational simulation, sustainability in Geomechanics, Information Technology (IT) applications, and system-identification procedures. He is author and co-author of over 300 Technical Publications. During 2010-2020, he served as Editor-in-Chief of the Journal Soil Dynamics and Earthquake Engineering. Over the years, has consulted and provided professional services in the general areas of Geomechanics and Geotechnical Engineering for a number of national and international organizations. Recently, he is honored to receive the 2025 American Society of Civil Engineers (ASCE) H. Bolton Seed Medal.

Dr. Kirk Ellison, Ph.D., F.ASCE
Associate Principal, Ground Engineering Leader | Arup
Seismic Structure-Soil-Structure Interaction Analysis for Below-Grade Infrastructure: Guidance for Screening, Analysis, Validation, and Peer Review

Abstract: Whether or not it’s accounted for during design, nearby above-and below-grade structures impact each other’s performance during strong ground shaking. Therefore, understanding and evaluating seismic structure-soil-structure interaction (SSSI) impacts is important for the resilience of our cities and the success of many of our projects. This is why seismic SSSI evaluations are now routinely required by many California agencies such as LA Metro, BART, San Francisco Public Utilities Commission, and Caltrans.

This presentation will discuss several examples of SSSI effects and introduce new guidance for screening, analysis, and model validations for SSSI impacts from new developments on existing underground infrastructure. In addition, case studies will be presented that touch on key SSSI considerations for buildings, rail stations, highways, and water infrastructure.

Bio: Kirk Ellison is an ASCE Fellow and Geotechnical Leader for Arup. He was recognized as the Outstanding Younger Civil Engineer by the ASCE San Francisco Section in 2018 for his contributions advancing the state of practice for seismic soil-structure interaction analysis on major rail, water and high-rise projects in the Bay Area. He also accepted international awards for the 181 Fremont Project in San Francisco, including the Outstanding Project Award from the Deep Foundations Institute and the Outstanding Tall Building Geotechnical Engineering Award from the Council for Tall Buildings and Urban Habitat.

Today, Kirk is a renowned expert in applying advanced soil mechanics and numerical modelling techniques to complex geotechnical problems across many sectors. He has published over 30 conference and journal papers. Some project highlights include the Salesforce Tower and 181 Fremont Tower projects in San Francisco, the Gerald Desmond Bridge in Long Beach, the Francis Scott Key Bridge replacement in Baltimore, the Silicon Valley Clean Water Gravity Pipeline in Redwood City, and the BART to Silicon Valley CP2 tunnel in San Jose.

Dr. Youssef Hashash, Ph.D., P.E., F.ASCE, NAE
Professor, Grainger Distinguished Chair in Engineering, Department of Civil and Environmental Engineering | University of Illinois Urbana-Champaign
Modeling Seismic Site Effects and Soil-Structure Interaction: A 1D-to-3D Nonlinear Analysis Framework Including Liquefaction

Abstract: Reliable assessment of seismic risk of infrastructure requires an integrated understanding of nonlinear soil behavior, site effects, and soil-structure interaction (SSI).  While one-dimensional (1D) nonlinear and equivalent linear site response analysis remains an essential prerequisite for evaluating ground motion, understanding complex seismic soil-structure interactions requires the use of advanced three-dimensional (3D) modeling approaches. This presentation will highlight developments in 1-D nonlinear site response analysis as a steppingstone to multidimensional soil structure interaction evaluation using accessible soil modeling capable of representing small strain nonlinearity all the way to liquefaction initiation. Several example applications will be presented including building tunnel interaction, response of nuclear power plant structures, buried water reservoirs, as well as liquefaction response using selected centrifuge and laboratory tests as well as field response measurements.

Bio: Professor Youssef Hashash holds a B.S., an M.S. and a Ph.D. (1992) in civil engineering from the Massachusetts Institute of Technology. He began his career with the PB/MK TEAM in Dallas on the Superconducting Super Collider Project and then Parsons Brinckerhoff in San Francisco working on underground construction projects in the U.S. and Canada including the Boston Central Artery/Tunnel project. He is a licensed professional engineer in California.

Professor Hashash joined the faculty of the Department of Civil and Environmental Engineering at the University of Illinois at Urbana-Champaign in 1998. He teaches courses and conducts research in Geotechnical Engineering, Numerical Modeling in Geomechanics, Geotechnical Earthquake Engineering, Tunneling in Soil and Rock, and Excavation and Support Systems. In addition, he also works on geotechnical and tunneling applications of deep learning, artificial intelligence, visualization, augmented reality, and imaging. He has published over 300 articles and is co-inventor on four patents. His research group developed the software program DEEPSOIL (now RSSeismic) that is used worldwide for evaluation of soil response to earthquake shaking. His work on seismic design of underground structures is extensively used in engineering practice.

Professor Hashash is a Fellow of the American Society of Civil Engineers (ASCE), a past president of the Geo-Institute of ASCE and has received several teaching, university and professional awards including the Presidential Early Career Award for Scientists and Engineers and the ASCE 2014 Peck Medal. He was elected to the National Academy of Engineering in 2022, one of the highest recognitions for engineers in the US.

Dr. Juan Manuel Mayoral, Ph.D.
Professor, Institute of Engineering | Universidad Nacional Autónoma de México
Seismic Performance of Tunnel-Building-Bridge Systems in Urban Environments

Abstract: The Seismic performance of tunnels during earthquakes in densely populated areas requires assessing complex interactions with existing infrastructure such as bridges, metro stations facilities, and low- to medium-rise buildings. This has become more challenging because the distance between surface and underground structures has been shortened to optimize the urban environment functionality. This is even more important in transit transfer stations, which usually comprise tunnels, bridges, and buildings, in which wave propagation interference is exacerbated. Key insights gathered from instrumentation of actual structures and numerical parametric studies are presented. A metro station currently under construction, located near by a 5-story masonry building, was selected as a test site for seismic instrumentation. The site is in Mexico City, in the so-called hill zone, where very cemented sandy silt and silty sands is found. An arrangement of five accelerometers was deployed, to assess free-field, near-field, and building seismic response. Some of the results gathered from the seismic instrumentation after recording five low- to high-magnitude earthquakes from both interface and intraplate events are commented. Major findings of the parametric studies are also highlighted. Three-dimensional finite difference models were developed using the software FLAC3D. Initially, the static response of the tunnel was evaluated accounting for the excavation technique. Then, the seismic performance evaluation of the tunnel was carried out, computing ground deformations and factors of safety, considering soil nonlinearities. Good agreement was observed between predicted and observed damage during post-event site observations during actual earthquakes. Once the soundness of the numerical model was established, a numerical study was undertaken to investigate the effect of frequency content in tunnel-induced ground motion incoherence for tunnels built in cemented stiff soils, considering both intraplate and interplate earthquakes, to assess the effect of differences in their frequency content, duration, and intensity. Multiple scenarios were considered in the numerical study, and the relative distances among the structures were varied to investigate both detrimental and beneficial interaction effects, and to identify the zone of influence where this interaction leads to ground motion variability.

Dr. John S. McCartney, Ph.D., P.E., F.ASCE
Professor, Hal Sorenson Endowed Chair, Department of Structural Engineering | University of California, San Diego
Geotechnical Seismic Isolation Using Tire Derived Aggregate

Abstract: This presentation will focus on the reuse of shredded tires with large particle sizes as an alternative lightweight backfill material in dynamic geotechnical applications. Tire derived aggregates (TDA) have the advantages of low unit weight, high shear strength, and high damping ratio, although they may be more compressible than most backfill soils. The presentation will summarize relevant properties of TDA with large particle sizes from a comprehensive laboratory testing program using large-scale tests, including uniaxial compression, internal shear strength, interface shear strength with different soils and concrete, cyclic shearing, and pullout of geosynthetic reinforcements. Tests from large-scale foundation loading tests will be compared with predictions of the bearing capacity using theories developed for granular materials. This information will be integrated to understand the use of TDA layers in providing seismic isolation for shallow foundations using shake table tests. Focus will be provided on the kinematic rocking and sliding responses. The presentation will conclude with the path forward to using TDA as a low-cost geotechnical seismic isolation approach in buildings and transportation infrastructure.

Bio: John McCartney is a Professor in the Department of Structural Engineering at the University of California San Diego and holds the Hal Sorenson Endowed Chair in the Jacobs School of Engineering. His research interests include unsaturated soil mechanics, geosynthetics engineering, and energy geotechnics. His research has been awarded the Prakash Award in 2025, the Quigley Award in 2020, the Huber Research Prize in 2016, and the Croes Medal in 2012. He is the vice chair of the ASCE GeoInstitute Committee on Energy Geotechnics. He is the co-Editor-in-Chief of Computers and Geotechnics and serves on the editorial boards of several other journals.

Dr. Gilberto Mosqueda, Ph.D., F.ASCE
Professor, Department of Structural Engineering; Mervyn Lea (M. Lea) Rudee Endowed Chair in Jacobs School of Engineering; Director, Caltrans Seismic Response Modification Device (SRMD) Facility | University of California, San Diego
Performance of Ordinary Seismically Isolated Bridges Beyond Design Shaking

Abstract: Seismic isolation is widely used to improve bridge performance under design-level earthquake demands; however, system behavior under beyond-design-basis loading remains less understood. Current Caltrans design provisions for seismically isolated bridges consider the isolation system as the primary earthquake resisting system (ERS), supplemented by a secondary earthquake resisting system (SERS) intended to engage for beyond design loading prior to the isolation layer reaching critical limit states. The SERS can be in the form of ductile substructure columns designed to undergo controlled plastic hinging, thereby redistributing deformation demands and delaying isolation system failure. To investigate this interaction, a shake table experimental program was conducted on a quarter-scale, two-column reinforced concrete bridge bent equipped with lead rubber bearings and designed in accordance with Caltrans minimum design requirements. Throughout beyond design testing, the isolation system demonstrated stable hysteretic behavior, with peak shear strains in bearings limited due to interaction with the substructure. Following SERS activation, deformation demands and energy dissipation increasingly shifted to the columns that also maintained stable hysteretic response, while the isolation layer continued to dissipate energy at a reduced proportion. These results demonstrate that controlled column yielding can effectively limit isolation system demands and provide a stable load path under beyond design loading for collapse prevention. This design approach is being examined for more cost-effective and widespread implementation of seismic isolation in ordinary bridges.

Bio: Gilberto Mosqueda is a Professor in the Department of Structural Engineering and the Mervyn Lea (M. Lea) Rudee Endowed Chair in the Jacobs School of Engineering at the University at California, San Diego. Previously, he was on the faculty at the University at Buffalo. He received his Ph.D. from the University of California at Berkeley, M.S. from Massachusetts Institute of Technology, and B.S. from the University of California, Irvine, all in civil engineering. Professor Mosqueda is the Director of the Caltrans Seismic Response Modification Device Test Facility, testing full-scale seismic isolation and damping devices. Professor Mosqueda is the recipient of the NSF CAREER Award, the American Society of Civil Engineering Moisseiff Award, the Mexico College of Civil Engineering Jose A. Cuevas Award, and a Fellow of ASCE.

Dr. Ramin Motamed, Ph.D., P.E.
Professor, Department of Civil and Environmental Engineering | University of Nevada, Reno
Liquefaction Beyond Triggering: What Medium- and Large-Scale Experiments Reveal About Soil–Foundation System Response

Abstract: Liquefaction assessment in engineering practice has traditionally focused on triggering criteria, often with limited consideration of the complex post-triggering mechanisms governing soil deformation and foundation performance. While simplified procedures and numerical models have advanced over recent decades, important aspects of liquefaction-induced system response remain insufficiently understood due to the scarcity of high-quality experimental data at large physical scales.

This presentation synthesizes findings from a series of medium- and large-scale 1g shake table experiments conducted over the past decade to investigate the response of shallow foundations and mitigation systems in liquefiable soils. The experimental studies include tests on untreated and improved ground conditions subjected to varying seismic loading characteristics and foundation configurations. Emphasis is placed on mechanisms that are difficult to capture using conventional laboratory element tests or simplified analytical procedures such as surface manifestation and soil ejecta.

Results demonstrate that liquefaction triggering alone is often insufficient for evaluating seismic performance, as similar triggering conditions may lead to different deformation and settlement outcomes. The experiments further highlight the important role of physical modeling in revealing system-level response mechanisms and in supporting validation of advanced numerical simulations and performance-based engineering approaches.
The presentation concludes with a discussion of unresolved challenges in liquefaction engineering and opportunities for integrating large-scale experimental observations into future design methodologies and seismic performance assessment frameworks.

Bio: Dr. Ramin Motamed is a Professor in the Department of Civil and Environmental Engineering at the University of Nevada, Reno. His research focuses on geotechnical earthquake engineering, including large-scale shake table testing, liquefaction and its mitigation, nonlinear site response, and soil–foundation–structure interaction. He has led numerous federally sponsored and industry-supported research projects in these areas, with particular emphasis on experimental investigation and validation of seismic soil–structure response mechanisms.

Dr. Motamed currently serves on the editorial board of the ASCE Journal of Geotechnical and Geoenvironmental Engineering and as Secretary of the ASCE Geo-Institute’s Earthquake Engineering and Soil Dynamics Committee. He received his Ph.D. from the University of Tokyo, where his doctoral research focused on pile foundations in liquefiable soils using shake table tests. Prior to joining academia, he worked as a Senior Engineer with Arup in San Francisco on major infrastructure and seismic engineering projects. He is a registered Professional Engineer in California and Nevada.

Dr. Chukwuebuka (Buka) C. Nweke, Ph.D.
Assistant Professor, Sonny Astani Department of Civil and Environmental Engineering | University of Southern California
Sustainable Ground Improvement Under Seismic Loading: Experimental Insights and Probabilistic Modeling of Biocemented Sands

Abstract: As the geotechnical community moves toward sustainable alternatives to Portland cement–based ground improvement, biocementation has emerged as one of the most promising bio-mediated techniques for stabilizing problematic soils and enhancing their resistance to seismic loading. Despite this promise, adoption in performance-based design remains limited because both the experimental practices used to characterize biocemented soils and the predictive models used to design with them fail to represent realistic field conditions. Most laboratory studies induce calcium carbonate precipitate in unconfined specimens before applying confining stress, a sequence that does not replicate the in-situ stress state during treatment, while the reference-strain models routinely used to estimate shear modulus reduction are calibrated almost exclusively on uncemented soils. Our research addresses both shortcomings in parallel. On the experimental side, we developed a custom resonant column device that enables enzyme-induced carbonate precipitation and dynamic testing under controlled confinement without specimen disturbance, revealing that the stress state during precipitation governs bond microstructure and the resulting dynamic response, just as strongly as the amount of calcite produced. On the modeling side, we are developing a Bayesian framework that infers the reference shear strain and its cementation-induced shift from measurable inputs such as cement content, confining stress, density, and gradation, while quantifying the uncertainty in each prediction. By linking microstructural evidence from realistic treatment conditions to a probabilistic prediction framework, this work aims to provide a foundation for the performance-based use of biocemented ground in seismic geotechnical applications.

Bio: Dr. Chukwuebuka (Buka) Nweke is an Assistant Professor of Civil and Environmental Engineering at the University of Southern California, Viterbi School of Engineering. He directs the N.E.S.T Research Group where his research is focused on solving problems at the intersection of geotechnical engineering, earthquake engineering, seismology, and geomorphology. Some of his investigation topics include: characterizing sedimentary basin effects in earthquake hazards, evaluation of physics-based earthquake simulations for the purposes of analyzing associated hazards and improving infrastructure resilience, and investigating the mechanical behavior (static and dynamic) of bio-cemented soils in order to establish sustainable alternatives for hazard mitigation.

Prof. Nweke earned his Ph.D. and M.S in Civil (Geotechnical) and Environmental Engineering at the University of California, Berkeley, and his B.S in Civil and Environmental Engineering at the University of California, Davis. After completion of his graduate studies, Professor Nweke was an NSF-AGEP Postdoctoral Research Fellow in the Civil and Environmental Engineering department at the University of California, Los Angeles. Prior to his current position, he was a practicing engineering consultant for ENGEO, a geotechnical and environmental engineering firm.

Dr. Renmin Pretell, Ph.D.
Assistant Professor, Department of Civil and Environmental Engineering | University of Nevada, Reno
Liquefaction Effects on Ground Motions

Abstract: Liquefaction assessment is a critical component of seismic design of infrastructure. Commonly, factors of safety against liquefaction triggering (FS_liq) are used to assess the liquefaction potential, where liquefaction is expected if FS_liq is lower than one. For this condition, ground motions are commonly believed to be damped out or not fully propagated to the ground surface, essentially leading to ground motion de-amplification. However, dilation spikes can instead lead to ground-motion amplification. Whether soil liquefaction leads to ground motion amplification or de-amplification depends on several factors, including the soil’s relative density, depth and thickness of the layer experiencing liquefaction, ground motion characteristics, and the period range of interest. This talk will share results from a numerical study and a consistency assessment against experimental data and ground motion recordings from borehole array sites.

Bio: Renmin Pretell is an Assistant Professor of geotechnical engineering in the Department of Civil and Environmental Engineering at the University of Nevada, Reno. He received his Ph.D. and M.S. from the University of California, Davis, and his B.S. from the National University of Engineering in Peru. Before joining UNR, Renmin was a postdoctoral scholar with the Garrick Institute for the Risk Sciences (GIRS) at the University of California, Los Angeles. He worked with Golder Associates at its offices in Lima, Peru and Denver, CO, focused on tailings dam projects. Renmin’s research aims to advance the performance assessment of geotechnical systems and infrastructure by integrating data, numerical simulations and analytics. His research interests include seismic site response and ground motions, soil liquefaction, and mine tailings.

Dr. Ellen Rathje, Ph.D., P.E., F.ASCE, NAE
Janet S. Cockrell Centennial Chair in Engineering, Fariborz Maseeh Department of Civil, Architectural, and Environmental Engineering | University of Texas, Austin
Induced Seismicity in Texas: Ground Motions and Seismic Risk

Abstract: Seismicity in Texas has increased significantly over the last 20 years; more than 1200 earthquakes with M > 3 have occurred since 2017, including 7 events with M > 5.  The Texas Seismological Network was established in 2015 to monitor seismicity in Texas and perform research to better understand the potential causes and impacts of earthquakes in Texas.  This presentation will summarize the TexNet seismic hazard and risk research performed over the last 10+ years.  Seismic hazard assessment starts with seismicity rates and ground motion models.  The approaches developed to predict seismicity rates as a function of operational parameters (e.g., injection rates) will be presented, as they provide a mechanism to forecast seismicity for different injection scenarios.  Empirical ground motion models will be described that incorporate over 12,000 ground motion recordings across the induced seismicity regions of Texas, Oklahoma, and Kansas.  These ground motion models also take advantage of a statewide Vs30 map that incorporates Vs30 measurements and geologic proxies based on geologic age and general rock/soil type.  Finally, ground motions from the region are used to investigate the potential to cause damage to earth dams through the development of seismic demand and fragility models.

Bio: Dr. Ellen M. Rathje is the Janet S. Cockrell Centennial Chair in Engineering in the Fariborz Maseeh Department of Civil, Architectural, and Environmental Engineering and a Senior Research Fellow at the Bureau of Economic Geology at the University of Texas at Austin.  She is an expert in the areas of engineering seismology, seismic ground response, and earthquake-induced ground failure.  Dr. Rathje is the current President of the Earthquake Engineering Research Institute and she is a founding member and previous Co-Chair of the Geotechnical Extreme Events Reconnaissance (GEER) Association. She leads the DesignSafe cyberinfrastructure that supports research in natural hazards engineering.  She has been honored with the 2022 Peck Lecture Award from the ASCE Geo-Institute, the 2018 William B. Joyner Lecture Award from the Seismological Society of America and the Earthquake Engineering Research Institute. She was elected the National Academy of Engineering in 2025.

Dr. José I. Restrepo, Ph.D.
Director of Research & Development | Nabih Youssef & Associates
Building Response to Six-Component Ground Motion Input

Abstract: The

Two high-definition seismic stations, located 30 m apart and within 1 km of the fault rupture, recorded the near-field motions of the 6 February 2023 Mw 7.8 Kahramanmaraş–Pazarcık earthquake. For the first time, near-fault rotational ground-motion components—pitch, roll, and yaw—derived from a major earthquake are estimated and used as inputs to nonlinear response-history analyses of 3D reinforced-concrete building models. The case studies show that rotational components increase key engineering response parameters. These findings underscore the importance of measuring and incorporating rotational ground-motion effects in seismic design codes and guidelines to better mitigate the vulnerability of structures near active faults.

Bio: José I. Restrepo pairs visionary leadership with a track record of delivering measurable impact on earthquake engineering and seismic design. As NYA’s Director of Research & Development, he builds on more than three decades of pioneering academic work and industry collaboration. Previously, Dr. Restrepo held professorships at the University of California, San Diego; the University of Canterbury, New Zealand; and the ROSE School, Italy, where he guided graduate talent and led internationally funded research initiatives. Most notably, he served as Principal Investigator for the NSF-funded Large High-Performance Outdoor Shake Table (LHPOST)—the world’s largest and most powerful earthquake-simulation facility by many metrics— shepherding the project from concept through commissioning and conducted several landmark tests on it.

As a scholar, Dr. Restrepo has authored papers on performance-based seismic design (PBSD), seismic response of high-rise buildings, forensic collapse assessment, seismic isolation, and other advanced response-modification strategies. He played a key role in advancing nonlinear response-history analysis techniques for critical structural components, including core walls, diaphragms, and systems involving soil–structure interaction. His technical expertise directly informed the development of PBSD guidelines and standards for bridges and AASHTO seismic hazard maps, and container wharves (ASCE-COPRI). He was also a member of ACI Subcommittee 318R during the 2014-2019 cycle and has been an active member of ACI Committees 319 (Precast Concrete Code), 374 (Performance-based seismic design), and 550 (Precast Concrete).

Dr. Restrepo’s contributions have been recognized by the field’s top honors, including the ACI Chester Paul Siess Award; PCI’s Charles C. Zollman and Martin Korn Awards; the FHWA James Cooper Award; and ASCE’s Charles Pankow and Alfred Noble Awards— underscoring the real-world value and lasting influence of his work.

Dr. Adrian Rodriguez-Marek, Ph.D.
Professor, Charles E. Via, Jr., Department of Civil and Environmental Engineering; Director, Center for Geotechnical Practice and Research | Virginia Tech
Epistemic Uncertainty in Site Response

Abstract: Estimates of site response are an important component in the estimation of earthquake induced ground motions. These estimates can be made via proxy methods, such as the use of V_S30 in ground motion prediction equations, or via analytical approaches, such as one-dimensional (1D) site response. The latter require the knowledge of a shear-wave velocity profile and the dynamic properties of the soils that make up the profile. These data carry measurement uncertainty, which is propagated to the uncertainty in site effects estimates. In addition, the methods used for analytical estimates of site response have their own modeling uncertainty. This presentation discusses approaches to estimate the uncertainty in site response estimates, as well as efforts made to quantify the modeling uncertainty for 1D site response analyses. The focus is on approaches used in seismic hazard analyses for nuclear sites, but the lessons learned have application in every-day engineering practice.

Bio: Dr. Adrian Rodriguez-Marek obtained his B.S. and M.S. in Civil Engineering from Washington State University, and his Ph.D. from U.C. Berkeley in 2000 working under the guidance of Prof. Jonathan Bray. After getting his Ph.D. in August 2000 Adrian went back to WSU as an Assistant Professor. He stayed at WSU until 2010 when he moved to Virginia Tech where he is now a professor in the Civil and Environmental Engineering Department. Dr. Rodriguez-Marek’s research is in the general area of geotechnical earthquake engineering. He has led NSF-funded reconnaissance teams to study the geotechnical aspects of three separate earthquakes (2001 Southern Peru; 2003 Colima, Mexico; and 2007 Pisco, Peru earthquakes). These reconnaissance efforts included the evaluation of earthquake damage to water dams and tailing dams. He has also made contributions to the engineering characterizations of ground motions in general and near-fault ground motions in particular.

Dr. Rodriguez-Marek has been a leading developer of non-ergodic seismic hazard analysis, an approach that enables a more rigorous treatment of uncertainty in ground-motion predictions for hazard applications. His research on single-station standard deviation has been applied in multiple seismic hazard assessments for nuclear power plants. In addition, he has served as a consultant on several high-profile projects, including the seismic hazard and risk assessment for the Groningen Gas Field and seismic hazard assessments for nuclear power plants in South Africa, Spain, Slovakia, Poland, and the United States.

Dr. Rodriguez-Marek’s scholarly output includes more than 80 peer-reviewed journal articles and 50 conference papers, as well as numerous technical reports on seismic hazard assessment. He has advised or co-advised thirteen Ph.D. students and has served as an external examiner on numerous doctoral committees in France, Germany, India, and New Zealand. His honors include the 2021 Outstanding Paper Award from the Earthquake Engineering Research Institute, the 2013 Shamsher Prakash Research Award, and the 2024 Collingwood Prize from ASCE. Dr. Rodriguez-Marek is a past Chair of the Soil Dynamics and Earthquake Engineering Committee of the ASCE Geo-Institute, currently serves as an Editor of the Journal of Geotechnical and Geoenvironmental Engineering, and is a past Associate Editor of several journals, including Earthquake Spectra and the Bulletin of the Seismological Society of America.

Dr. Kenichi Soga, Ph.D.
Distinguished Professor, Donald H. McLaughlin Chair, Civil and Environmental Engineering; Director, Berkeley Center for Smart Infrastructure; Faculty Scientist, Lawrence Berkeley National Laboratory | University of California, Berkeley
Preparing for the Next-Next Big Earthquake

Abstract: In September 2015, at the Yokohama National University Campus, Professor Yozo Fujino (Professor Emeritus, University of Tokyo) and I organized a symposium titled “Challenges in Geotechnical Engineering from the Perspective of Risk Coexistence.” We invited eleven leading Japanese professors in geotechnical engineering to present lectures focused on the theme of risk in this field.  Professor Ishihara was one of the speakers and delivered a presentation entitled “Preparing for the Next-Next Big Earthquake.” He emphasized that there is currently an inadequate observational network capable of monitoring the behavior of shallow soft ground layers in coastal and riverside areas, where many of Japan’s industries and facilities are situated, during major earthquakes. He stressed the urgent need to install seismometers, displacement meters, and pore-water pressure gauges within soft ground deposits.  The observational records obtained during future major earthquakes through such instrumentation will help clarify the seismic behavior of important industrial facilities built on soft ground and will play an important role in advancing earthquake engineering. Professor Ishihara concluded “we should keep firmly in mind (kimo-ni-meijiru) that the earthquake engineering technologies verified through such field measurements in the next earthquake are the only ones that are truly effective in the next-next major earthquakes”. This talk will build upon Professor Ishihara’s important insights and emphasize the critical role of sensing and monitoring in developing resilient infrastructure for our society.

Bio: Kenichi Soga holds the Donald H. McLaughlin Chair and is a Distinguished Professor of Civil and Environmental Engineering at UC Berkeley. He serves as the Director of the Berkeley Center for Smart Infrastructure and is also a faculty scientist at Lawrence Berkeley National Laboratory. His research focuses on infrastructure sensing and modeling, performance-based design and maintenance of infrastructure, energy geotechnics, and geomechanics from micro to macro. He has published over 600 journal and conference papers and co-authored the book “Fundamentals of Soil Behavior” with Professors James K. Mitchell and Catherina O’Sullivan. He is a member of the National Academy of Engineering and a fellow of the UK Royal Academy of Engineering, the Institution of Civil Engineers (ICE), the American Society of Civil Engineers (ASCE), and the Engineering Academy of Japan.

Dr. Jonathan P. Stewart, Ph.D.
Sabol-Scott Professor, Civil & Environmental Engineering | University of California, Los Angeles
Revisiting Valley of Mexico Seismic Site Response

Abstract: For many years, design ground motions in Mexico City have been developed using a ground motion model (GMM) for a reference site combined with linear transfer functions between that reference site and different locations within the Valley of Mexico. This modeling approach is distinct from how ground motions are developed elsewhere in Mexico. We present an alternative in which a regionally-calibrated GMM for subduction zone earthquakes can be applied throughout Mexico including the Valley of Mexico, which is combined with a subregional site response model that accounts for the unique Lake Texcoco geology. The site response model was derived using ground motion data from 89 sites within the Valley of Mexico and uses VS30 and soft soil depths as independent variables. The model predicts far greater levels of site response than those provided by global ergodic models, and notably, larger site response than prior Mexico City models. A notable feature of the updated site response model is incorporation of nonlinearity for high-frequency ground motions. The provided models afford the opportunity to improve upon current practice because the reference GMM applies across Central America and Mexico, VS30 and depth are used in lieu of site classes, and nonlinearity is incorporated.

Bio: Jonathan P. Stewart’s is the Sabol-Scott Professor of Civil & Environmental Engineering at the UCLA Samueli School of Engineering. His technical expertise is in geotechnical engineering, earthquake engineering, and seismology. He works on problems related to hazard characterization and infrastructure response to those hazards.

Dr. Ikuo Towhata, Ph.D.
Professor Emeritus | University of Tokyo
My Thoughts on 2025 Mandalay Earthquake in Myanmar and the Observed Fault Rupture

Abstract: I visited the affected sites in June 2025, which was about two months after the earthquake. It was found that the RC buildings in Myanmar have structural weakness in the ground floor where there are few stable walls. The collapse of the lower floor led to the collapse of the entire structure and resulted in numerous casualties. The rupture of the Sagaing Fault was of right-lateral strike-slip type without a recognizable vertical component. The fault-induced damage of structures was limited within, say, ten meters from the surface manifestation of the dislocation and indicated that there was no exceptionally strong ground shaking near the fault. It is not easy to discuss the possibility of a supershear rupture mechanism because of the shortage of earthquake observation network but the high-rise building damage in Bangkok was not the consequence of a super-shear mechanism but the result of long-period amplification of the ground motion in a soft soil deposit.

Bio: Ikuo Towhata was a professor of civil engineering at the University of Tokyo until 2015. After 2015, he has been working for private sectors together with several engineering/academic societies, including the Japanese Geotechnical Society as the president and the Int. Soc. Soil Mech. Geotech. Engg. as a vice president. His recent interests lie in geotechnical earthquake engineering, mitigation of slope disasters and the engineering perspective of tectonic action of the earth crust. He has authored more than 500 academic papers in international journals and conferences together with three books entitled ‘Geotechnical Earthquake Engineering’ (2008, Springer), ‘Coseismic landslides: phenomena, long-term effect and mitigation’ (with 17 coauthors with three coeditors, 2022, Springer) and ‘Slope Monitoring for Early Warning of Rapid Landslides – Mitigating Rainfall-induced Disasters -’ (2026, CRC Press), respectively. He was the Ishihara Lecture of TC203, ISSMGE, in 2019, and the 2026 Burmister Lecturer of the Columbia University.

Dr. Yoshimichi Tsukamoto, Ph.D.
Professor, Department of Civil Engineering | Tokyo University of Science
Developments in Soil Liquefaction Engineering Achieved with Prof. Ishihara During the Last 30 Years

Abstract: The author has worked together with Professor Ishihara during the last 30 years on many research topics associated with soil liquefaction. In this presentation, some of the main developments achieved through laboratory testing and field observations are presented, including (a) characterising the undrained shear strength of fines-containing sands, (b) characterising the post-liquefaction settlement of fines-containing sands, (c) evaluating the liquefaction resistance of imperfectly saturated sands, (d) characterising the penetration resistance of SWS tests for estimating the liquefaction resistance and undrained shear strength of fines-containing sands.

Bio: Yoshimichi Tsukamoto graduated from the University of Tokyo in 1990 and received his Ph.D. from University of Cambridge in 1995. He then moved to Tokyo University of Science (TUS) as a research associate in 1995, where he became a full professor in 2012. He has devoted his research career mainly to the subject of soil liquefaction, including laboratory testing and field case history studies from recent major earthquakes in Japan. He has been associated with Professor Ishihara who moved to TUS in 1995 and continued to work together on many research projects until recently.

Dr. Ramon Verdugo, Ph.D.
Founding Partner | Caracterización y Modelamiento Geotécnico Ingenieros (CMGI Ltda.)
Undrained Triaxial Tests with Stepwise Volumetric Strain Applications

Abstract: To evaluate the critical state line (CSL) of sandy soils in the laboratory with a high degree of confidence, typically is required more than four or six undrained tests to reliably establish the CSL in the e-p’ and q-p’ planes. To address this efficiency challenge, this study proposes a new procedure that captures multiple CSL data points using a single specimen. Referred to as the “void ratio-controlled test,” this method consists of several steps where
the undrained condition is briefly bypassed. This short interruption allows the specimen to undergo a pre-established volume change, effectively altering its void ratio for subsequent testing phases.

Bio: Civil Engineer from the Catholic University of Chile (1983), holding a Master and Ph.D. from the University of Tokyo, Japan (1989 and 1992, respectively). He completed a postdoctoral fellowship at the Norwegian Geotechnical Institute (1996). He has served as Director, Secretary, and President of the Chilean Geotechnical Society (Sochige). Following the mega-seismic event of magnitude Mw = 8.8 that hit Chile in February 2010, he led the team of professionals that modified the seismic site classification in Chilean regulations. He served as the Chair of Technical Committee TC221 (Tailings and Mine Waste) of the International Society for Soil Mechanics and Geotechnical Engineering. He is a founding partner of the Chilean geotechnical engineering consulting firm CMGI Ltda. (Caracterización y Modelamiento Geotécnico Ingenieros), which addresses complex geotechnical problems, especially those associated with the seismic stability of soil structures in civil, industrial, and mining projects.

Advanced Tools for Site Response Analysis | A One-Day Short Course

September 9th, 2026
University of California, San Diego
Franklin Antonio Hall 1301

Join us for the 8th Kenji Ishihara Colloquium Series on Earthquake Engineering, hosted by the EERI UCSD Student and San Diego Regional Chapters. This year’s colloquium will consist of a one-day short course on September 9th about Advanced Tools for Site Response Analysis featuring Professor Ellen Rathje, Dr. Albert Kottke, and Professor Adrian Rodriguez-Marek, followed by a lineup of notable speakers on September 10th & 11th covering topics in tribute to the late Professor Kenji Ishihara.

Site response analysis is one of the most commonly performed types of analysis in geotechnical earthquake engineering. New approaches have been developed for site response analysis that can (1) enhance the efficiency of the analysis (i.e., random vibration theory, RVT), (2) incorporate uncertainties in the input properties (i.e., statistical variation of properties), and (3) improve site response predictions at larger strains (i.e., frequency-dependent properties, kappa scaling). These advancements have been incorporated into the publicly available and open-source site response programs Strata and pyStrata. Strata is a stand-alone program that includes an easy-to-use graphical user interface for both providing input data and analyzing output results. pyStrata is a Python package that implements many of the features included in Strata, plus a few more, and allows for developing custom workflows. In this short course, we will describe the recent advancements listed above, explain their incorporation into Strata and pyStrata, and provide live demonstrations and hands-on exercises. Example applications of these approaches will also be presented.

Click the images to the above-right and below to view the event flyer and announcement slides, respectively.

PROGRAM

VENUE
University of California, San Diego
Franklin Antonio Hall 1301
3180 Voigt Drive
La Jolla, CA 92093

REGISTRATION
Click here to register for the short course. Early bird registration will be available through 8/10/2026. You will be prompted to register into your my.eeri.org account when you click the blue “Register to Attend” button on the registration page. If you do not have an EERI account, use the “Sign Up” button to create one. We strongly recommend each registrant create an individual EERI account to ensure all communications—including receipts and PDH credits—are received. Accepted payment methods are credit card (MasterCard, Visa, Discover) and ACH. If you need to pay by wire transfer, please contact eeri@eeri.org.

LODGING
Click here for a list of hotels near UCSD.

PARKING
For $8 per day, conference parking permits are available in advance through UCSD’s Parking Portal website, which you can access by clicking here. In order to purchase a parking permit, you will need to create an account. When you click on the aforementioned link, it should show a “Guest User Registration” form. Otherwise, click on “SIGNUP” in the upper right corner of the webpage. Once you fill out the form and create an account, follow the prompts to purchase your conference parking permit for the days you will be attending the colloquium.

You can also pay for parking through the ParkMobile app or website the day(s)-of the colloquium series. More information can be found here.

There are two structures available for parking near Franklin Antonio Hall: Hopkins and Pangea. The closest parking structure to the venue is Hopkins Parking Structure (view here or here), located on Voigt Dr. off of Hopkins Dr. If Hopkins is full, please go to Pangea Parking Structure (view here or here), located on Pangea Dr. off of N. Torrey Pines Rd. You may only park in B-spaces with your pre-purchased conference parking permit.

Click image below to see the parking structures and venue highlighted (from https://maps.ucsd.edu/map/default.htm):

Click image below to see the parking structures and venue highlighted on Google Maps (from https://act.ucsd.edu/maps/):

MEET THE INSTRUCTORS

Dr. Ellen M. Rathje, Ph.D., P.E., NAE is the Janet S. Cockrell Centennial Chair in Engineering in the Fariborz Maseeh Department of Civil, Architectural, and Environmental Engineering at the University of Texas at Austin.   Her research focuses on earthquake ground motions, site response, and earthquake-induced ground failure, including the development of new approaches and tools for site response analysis.  As a consultant, she has been involved in seismic hazard studies for nuclear facilities around the world, including sites in the US, Taiwan, South Africa, and Poland. Her awards include the 2022 Peck Lecture Award from the ASCE and the 2018 William B. Joyner Lecture Award from the Seismological Society of America and the Earthquake Engineering Research Institute (EERI). She is currently the President of EERI and was elected to the National Academy of Engineering in 2025.

Dr. Adrian Rodriguez-Marek, Ph.D., is a Professor and Director of the Center for Geotechnical Practice and Research in the Charles E. Via, Jr. Department of Civil and Environmental Engineering at Virginia Tech. His research focuses on geotechnical earthquake engineering, with an emphasis on site response and seismic hazard analysis. His major research contributions include ground motion characterization and the treatment of uncertainty in seismic hazard analysis, particularly the development of the concept of non-ergodic seismic hazard analysis. As a consultant, he has participated in seismic hazard assessment projects for nuclear power plants and critical facilities around the world. His awards include the 2021 Outstanding Paper Award from EERI and the 2024 Collingwood Prize from ASCE.

Dr. Albert Kottke, Ph.D., P.E., has over 16 years of experience in site response and earthquake ground motions. He spent five years at Bechtel Corporation developing site-specific ground motions for nuclear facilities and supporting soil-structure-interaction analyses. Since 2017, he has been a Principal in PG&E’s Geosciences Department, where he advances ground motion modeling and seismic risk assessment. As a consultant, he has contributed to seismic evaluations for various critical facilities, including Columbia River Generating Station, Idaho National Laboratory, and Los Alamos National Laboratory. He also authors and maintains computer programs such as Strata, pyStrata, pygmm, and pyrotd.

RESPONSE SPECTRUM METHODS IN EARTHQUAKE ENGINEERING

Tuesday, 8.11.2026
12pm-1pm PDT
Virtual Event

The response spectrum analysis method is widely used for determining the response of linear structures to earthquake ground motions. Many codes of practice recommend the CQC (Complete Quadratic Combination) modal combination rule for this purpose. In this talk, Dr. Armen Der Kiureghian will describe the assumptions behind this method and provide its advantages and shortcomings. He will then describe extended versions of this method for (a) structures subjected to multiple components of ground motion, (b) structures with multiple supports (e.g., bridges), (c) structures with high-frequency modes, and (d) non-classically damped structures. Examples for each case will be presented.

Click the image on the above right to view the event flyer.

REGISTRATION
Click here to register for the webinar by 10am PDT on 8/11 to ensure you receive the webinar link. You do not need to be an EERI member to attend. However, you will need to sign into your account on EERI’s new member portal. If you haven’t yet reset your password to do so, view the instructions here.

SPEAKER
Dr. Armen Der Kiureghian, Ph.D.
Professor Emeritus, American University of Armenia
Taisei Professor of Civil Engineering Emeritus of the University of California, Berkeley
Armen Der Kiureghian is President Emeritus of the American University of Armenia and Taisei Professor of Civil Engineering Emeritus of the University of California, Berkeley. His teaching and research are in risk and reliability of constructed facilities, stochastic structural dynamics, earthquake engineering, and engineering decision making. He has authored more than 130 refereed journal papers and three books, including Structural & System Reliability by Oxford University Press. Among other awards, he is the 2026 recipient of the American Society of Civil Engineers’ Nathan M. Newmark Medal. Der Kiureghian is an elected member of the U.S. National Academy of Engineering.

DEVELOPING TARGET VERTICAL RESPONSE SPECTRA AND TIMEI-HISTORY SELECTION AND MODIFICATION FOR THE VERTICAL COMPONENT

Wednesday, 8.5.2026
12pm-1:30pm PDT
Virtual Event

Join us for this free webinar presented by Dr. Norman Abrahamson to learn about vertical response spectra. Click the image on the right to view the event announcement.

Abstract
For engineering projects that require both horizontal and vertical components, it has been common practice to develop a vertical spectrum by scaling the horizontal design spectrum that by the median V/H ratio for the controlling scenario. This approach two two key limitations: (1) the relation between the ln(V(T)) and ln(H(T)) is assumed to be linear with a slope of 1.0 and (2) the correlation of the variability of the ln(V(T)) and ln(H(T)) is ignored. There is a large negative correlation. As a result, common practice using the median V/H overestimates the vertical spectrum that goes with the horizontal spectrum for a given return period, but this does not mean that the current approach is conservative because we need to also consider the case in which we start with the vertical spectrum for a given return period and find the horizontal spectrum conditioned on the vertical spectrum (analogous to developing conditional mean spectra for two conditioning periods). An alternative approach is proposed that uses the conditional ground-motion model approach which allows the slope between the ln(V(T)) and ln(H(T)) to differ from unity and greatly reduces the correlation.Using this approach, more realistic pairs of horizontal and vertical spectra can be developed for both the vertical spectrum conditioned on a horizontal spectrum and the horizontal spectrum conditioned on a vertical design spectrum.

A second topic is the scaling and modification of time histories for the vertical component. Because the vertical and horizontal components of the ground motions scaling differently with magnitude, distance, and site condition, the scale factors for the vertical component should be determined independent of the scale factor for the horizontal component and not be fixed to be the same as the scale factors for the horizontal component. The target variability of the vertical spectral values conditioned on the horizontal design spectrum is estimated from the correlation of the vertical and horizontal spectral values and the standard deviation of the vertical spectrum for the controlling scenario.

REGISTRATION
Click here to register for the webinar by 10am PDT on 8/5 to ensure you receive the webinar link. You do not need to be an EERI member to attend. However, you will need to sign into your account on EERI’s new member portal. If you haven’t yet reset your password to do so, view the instructions here.

SPEAKER
Dr. Norman Abrahamson
Adjunct Professor, University of California, Berkeley and University of California, Davis
Dr. Abrahamson is an internationally-known expert in seismic hazard and risk analyses, with a focus on the practical application of engineering seismology to the development of deterministic and probabilistic seismic criteria for engineering design and evaluations of seismic risk. He has been involved in developing or reviewing design ground motions for hundreds of critical infrastructure projects around the world. He is an adjunct professor at UC Berkeley, and UC Davis, where he teaches a graduate course on seismic hazard analyses, development of design time histories, and seismic risk. His current research is focuses on non-ergodic ground-motion and fault rupture models, treatment of aleatory variability and epistemic uncertainty in site response, numerically efficient methods for evaluating seismic hazard for complex source and ground-motions, and decision making using hazard or risk estimates with large epistemic uncertainties.

APPLICATION OF NONERGODIC SITE RESPONSE ANALYSIS TO SEISMIC RETROFIT PROJECTS

Thursday, May 14th, 2026
12pm-1pm PDT
Virtual Event

Non-ergodic site response analysis represents an advanced approach to characterizing ground motions for seismic design, accounting for site-specific effects beyond ergodic ground motion models (GMMs). While prior studies have primarily applied this method to SSHAC projects in the energy sector or new construction projects targeting the Maximum Considered Earthquake (MCER) risk level, very few non-SSHAC projects have employed non-ergodic methods, particularly in Southern California. As such projects are increasingly undertaken following recent changes in the NEHRP Provisions (Stewart et al. 2026), practical and technical issues are sure to arise for which best-practices will need to be defined. This study documents processes and results for case examples from two seismic retrofit projects in Los Angeles, California. These projects consider hazard levels that are lower than the MCER level and include the Basic Safety Earthquake-2E (BSE-2E, 5% exceedance in 50 years) and BSE-1E (20% exceedance in 50 years) hazard levels. These projects apply non-ergodic methods in retrofit contexts, where cost-effective hazard mitigation is critical, by incorporating nearby recordings and hazard-consistent inputs to refine site response estimates. They also identify key hurdles to implementation—such as data availability, computational demands, and integration with existing codes—and propose practical strategies for overcoming them.

The evaluations follow ASCE 41-23, the 2026 Los Angeles City Building Code, and ASCE 7-22. The scope includes subsurface investigation with deep surface wave surface wave soundings and ground motion hazard analysis using the following methods: mapped parameters (ASCE 41-23 Section 2.3.2), site-specific hazard analysis using ergodic GMMs (ASCE 41-23 Section 2.3.3, ASCE 7- 22 Chapter 21.2), hybrid ground response analysis (GRA) (ASCE 7-22 Chapter 21.1), GRA with hazard curve convolution (Bazzurro and Cornell, 2004), and non-ergodic SRA (Stewart et al., 2017) using nearby strong motion records and GRA. Each of these methods’ results are compared and commentary is provided on use cases for each method.

Click the image on the above right to view the event flyer.

REGISTRATION
Click here to register for the webinar by 11am PDT on May 14th to ensure you receive the webinar link. You do not need to be an EERI member to attend. However, you will need to sign into your account on EERI’s new member portal. If you haven’t yet reset your password to do so, view the instructions here.

Non-members can purchase one Professional Development Hour for $25, which will be provided free of charge to members.

SPEAKERS

• Dr. Martin Hudson, Ph.D., P.E., G.E., Principal Geotechnical Engineer, Hudson Geotechnics, Inc.
• Dr. Kenneth Hudson, Ph.D., P.G., E.I.T., Principal Geoscientist, Hudson Geotechnics, Inc.

COMPARISON OF IN-SITU AND LABORATORY TEST-BASED SOIL LIQUEFACTION AND CYCLIC SOFTENING RESPONSES

Tuesday, January 15th, 2026
6pm to 8pm
Sufi Mediterranean Cuisine
5915 Balboa Ave.
San Diego, CA 92123

Geo-Institute San Diego Chapter is co-hosting their January Meeting with EERI San Diego, featuring guest speaker Dr. Armin W. Stuedlein, PhD, PE, F.ASCE of Oregon State University. Please join us at Sufi Mediterranean Cuisine to hear about seismic and non-seismic responses of dynamic, in-situ tests.

For members of EERI or ASCE = $50
For non-members = $50
For student members of EERI or ASCE = $10

Click the image on the right to view the event flyer.

REGISTRATION
Click here to register for the meeting.

Abstract: This Presentation describes a series of dynamic, in-situ tests conducted within natural soil deposits to deduce their seismic and post-seismic responses and presents side-by-side comparison to the results of cyclic and post-cyclic laboratory test programs and/or laboratory test-based models to establish the similarities and differences between the two techniques. The deposits investigated included a low plasticity silt deposit at mean depth of 2.5 m, a moderate to high plasticity silt deposit at a depth of approximately 10 m, and a medium dense sand deposit at a depth of about 25 m. Two methods for applying seismic loading in-situ were deployed: vibroseis shaking and controlled blasting. In-shaking responses considered include relationships between direct simple shear- (DSS-) equivalent shear strain and maximum and residual excess pore pressure, and cyclic resistance. Post-shaking responses are compared in terms of settlements and volumetric strains to general and site-specific post-cyclic volumetric strain models for the medium dense sand and medium to high plasticity silt deposits, respectively. The post-shaking monotonic undrained shear strength of the medium to high plasticity silt deposit is compared to a site-specific post-cyclic strength model. Key issues surrounding the differences between laboratory and in-situ testing are identified and highlight relevant factors contributing to observed similarities and differences in the observations, including use of reconstituted specimens, and the efects of multidirectional shaking, partial drainage, and excess pore pressure redistribution-effects which are difficult to simulate in the laboratory.

Bio: Dr. Armin W. Stuedlein is a licensed professional engineer and Professor of Geotechnical Engineering in the School of Civil and Construction Engineering at Oregon State University. Armin received his MS and PhD in geotechnical engineering from Syracuse University (2003) and the University of Washington (2008), respectively. He joined the faculty at OSU in 2009 after consulting for Seattle-based firms, where he specialized in port and harbor engineering with an emphasis on foundation and earthquake engineering. The results of his research have been disseminated through 175+ publications and consultation for PacNW firms and focuses on liquefaction and cyclic softening through dynamic in-situ and cyclic laboratory testing, ground improvement, experimental and numerical investigations of soil-structure interaction, and probabilistic geotechnical analyses. His research is funded by various departments of transportation, the National Science Foundation, and industry partners. He is the Chair of the Soil Improvement Committee (ASCE G-I), outgoing Editor at the ASCE Journal of Geotechnical and Geoenvironmental Engineering, Editor at the Journal of the Deep Foundations Institute, and Editorial Board member for Georisk and the Canadian Geotechnical Journal. Professor Stuedlein received several awards, most recently the 2023 ASCE J. James R. Croes Medal and the 2023 and 2024 Fredlund Awards.

SITE CHARACTERIZATION USING V_S30 PER THE ASCE 7-22

Wednesday, January 14th, 2026
10:30am-12pm PST
Virtual Event

Starting January 1, 2026, the ASCE 7-22 standard will be effective all over the country. Among the new changes, site characterization will now be based solely on shear wave velocities, and not on shear undrained strengths or SPT N-values anymore. To provide guidance and clarification on how to make site characterization consistent with the new ASCE 7-22 standard, we are hosting a free webinar featuring Professor Jonathan Stewart and Professor Brady Cox. After presentations from the two speakers, we will have a 30-minute session for questions and answers.

Click the image on the right to view event announcement.

REGISTRATION
Click here to register for the webinar. You do not need to be an EERI member to attend.

SPEAKERS

• Dr. Jonathan Stewart is a Professor in the Samueli School of Engineering at the University of California, Los Angeles (UCLA) and a 2025 EERI Honorary Member.
• Dr. Brady Cox is a Professor in the Civil and Environmental Engineering Department at Utah State University (USU) and the founding director of the new Utah Earthquake Engineering Center.
• Jorge Meneses of the EERI San Diego Regional Chapter will moderate the webinar. Contact him with any questions about the event.

BREAKING THE BOUNDARIES OF LIQUEFACTION MITIGATION: ADVANCED SIMULATIONS + MACHINE LEARNING FOR SAFER SEISMIC DESIGN

Tuesday, December 16th, 2025
11:30am-1:03pm
Four Points by Sheraton, San Diego
8110 Aero Drive
San Diego, CA 92123

ASCE San Diego Section is co-hosting their December Lunch Program with EERI, featuring guest speaker Dr. Shideh Dashti, 2025 EERI Distinguished Lecturer. Please join us at Four Points Sheraton to hear about a novel method incorporating simulation and machine learning to improve seismic resilience.

For members of EERI or ASCE = $60
For non-members = $90
For public agency or student members of EERI or ASCE = $40

Click the image on the right to view the event flyer.

REGISTRATION
Click here to register for the luncheon.

Abstract: The existing engineering methodologies for mitigation of seismic liquefaction rely on free-field triggering in uniformly layered granular soil deposits. These methods do not evaluate performance, and they routinely ignore cross-layer interactions in realistically stratified deposits as well as soil-structure interaction (SSI). In this presentation, through an experimental-numerical-statistical study, we show that these methods are unreliable, jeopardizing our ability to assess and mitigate liquefaction vulnerability of our sites and structures. We performed more than 19,000 and 4,000 fully-coupled, 3D, dynamic finite element analyses of free-field site response and seismic SSI, respectively, in OpenSees. These simulations were calibrated and validated with element and centrifuge experiments. The datasets were designed using quasi-Monte Carlo sampling, to capture a wide range of critical parameters, including stratigraphic variability, soil types and properties, foundation and structure properties, mitigation mechanisms and geometry using dense granular columns (DGCs), and ground motion characteristics. The influence of stratigraphic variability on mitigation efficacy is shown to be significant in terms of foundation settlement, tilt, spectral accelerations, and flexural drift. Physics-informed, random forest, machine learning (ML) is subsequently used to identify the key predictors and models for free-field ejecta potential in highly nonlinear and stratified soil profiles, as well as mitigated/non-mitigated ratios of foundation’s vertical and lateral displacement and foundation and roof peak accelerations. The models show strong predictive performance on independent test sets, significantly reducing uncertainty and outperforming traditional regression techniques. Combining advanced numerical simulations and machine learning enables a new approach to liquefaction mitigation, one that accounts for seismic soil-structure interaction in realistic sites and structures.

Bio: Shideh Dashti is a Professor in Geotechnical Engineering and Geomechanics at the University of Colorado Boulder (CU) and the Associate Chair for Administration in the Department of Civil, Environmental and Architectural Engineering. She also directs a college-funded interdisciplinary research theme titled RISE: Resilient Infrastructure with Sustainability and Equity. Shideh obtained her undergraduate degree at Cornell University in 2004 and graduate degrees at the University of California, Berkeley in 2009. She worked briefly with ARUP and Bechtel on several engineering projects in the U.S. and around the world, spanning seismic design of underground structures, foundations, and slopes. Her research team at CU studies: the interactions and interdependencies among infrastructure systems during earthquakes and climatic extremes; seismic performance of underground structures; triggering, consequence, and mitigation of the liquefaction hazard at local and regional scales; impact of compound climatic-seismic hazards on geotechnical infrastructure; and the intersection of resilience, environmental sustainability, and justice. She is the recipient of the 2018 Arthur Casagrande Award and the 2021 Walter Huber Civil Engineering Research Prize from ASCE as well as the 2025 Distinguished Lecture Award from EERI, among other recognitions.

Fault Displacement
Speakers and Abstracts

Dr. Norman Abrahamson
Adjunct Professor, University of California, Berkeley and University of California, Davis
Selection of Design Fault Displacements for Moderate-Activity Faults

Abstract: Design ground-motion values are commonly based on probabilistic seismic hazard analysis (PSHA), whereas design fault displacement values have often been estimated using deterministic seismic hazard analysis. To treat ground motion and fault displacement consistently, there has been a growing demand for probabilistic fault-displacement hazard analysis (PFDHA) for selecting design fault displacements; however, choosing the fault displacement from a PFDHA based on the same return period as used for the ground motion may not lead to consistent levels of risk for moderate-activity faults (slip rate between 0.2 and 2 mm/yr) if the hazard curve has a flat slope at the selected return period. In this case, the epistemic uncertainty in the slip rate on the fault will lead to a very large range for the fault displacement at the selected return period.

For moderate-activity rates, alternative approaches for selecting a design fault displacement are described: risk-targeted displacement approach, high-fractile hazard approach, and median displacement given surface rupture at the site approach. If it is not practical to design for the fault displacement, an alternative approach is described in which an emergency action plan is developed to respond to the expected damage from fault displacement rather than design the structure to withstand the fault displacement.

Bio: Dr. Abrahamson is an internationally-known expert in seismic hazard and risk analyses, with a focus on the practical application of engineering seismology to the development of deterministic and probabilistic seismic criteria for engineering design and evaluations of seismic risk. He has been involved in developing or reviewing design ground motions for hundreds of critical infrastructure projects around the world. He is an adjunct professor at UC Berkeley, and UC Davis, where he teaches a graduate course on seismic hazard analyses, development of design time histories, and seismic risk. His current research is focuses on non-ergodic ground-motion and fault rupture models, treatment of aleatory variability and epistemic uncertainty in site response, numerically efficient methods for evaluating seismic hazard for complex source and ground-motions, and decision making using hazard or risk estimates with large epistemic uncertainties.

Frank Bannon, P.E.
Senior Engineer, Reid Middleton, Inc.
Evaluation of Existing Buildings Located on Active Fault Lines

Abstract: Current building regulations generally prevent new construction on known active fault lines due to fault rupture hazards. However, there is limited guidance on how to evaluate existing buildings that were constructed on fault lines before these regulations were put in place. ASCE 41 provides minimal guidance on analyzing and mitigating fault rupture hazards. This presentation is intended to initiate discussion about how engineering professionals can evaluate existing structures on fault lines that are subject to fault rupture. Included in this presentation is a case study of a 10-story reinforced concrete shear wall building with deep pile foundations where a recent geological investigation revealed that several fault lines were located directly underneath the building, with the potential to cause fault rupture at the surface level.

Bio: With more than 10 years of structural design experience, Frank works as a senior engineer and project manager for Reid Middleton, Inc. in San Diego, California. His project experience includes various structure types, including concrete tilt-up, concrete tanks, steel frames, steel pedestrian bridges, and retaining walls. He also has experience conducting seismic evaluations and provided associated seismic retrofit concept design. Frank is a licensed Civil Engineer in California. He holds a Bachelor of Science degree in Civil Engineering from the University of Delaware.

Craig D. Comartin
President, CDComartin, Inc.
Structural effects of large seismically induced permanent ground displacements
Unfortunately, Dr. Comartin is no longer able to present at this year’s colloquium.

Abstract: This presentation comprises three parts. First observations of building and foundation performance from past earthquakes are reviewed. From these the design implications for new and existing construction are presented. Finally, three case studies are presented as examples of applications of soil structure interaction for large permanent displacements of structures. The first is the construction of the state of Alaska Supreme Court building constructed upon the existing L Street Slide in Anchorage, AK. Two more examples are discussed both of which are on the University of California, Berkeley campus, one being the retrofit of California Memorial Stadium and the other being the retrofit of Bowles Hall immediately north of the Stadium.

Bio: Craig D. Comartin is a structural and geotechnical engineer with over 50 years of experience. His work includes both research and practical applications. He has developed procedures for including the effects of soil structure interaction there are now considered the standard in the industry. This includes the subject of this presentation on large permanent displacements at surface expressions of fault movement. He is former president of the Earthquake Engineering Research Institute. In this capacity he was instrumental in establishing local chapters of EERI including in San Diego. He has filed reports on numerous earthquakes from around the world. He is an honorary member of EERI and the Northern California Structural Engineers Association. He was awarded the Alfred Alquist Medal for his work raising awareness of non-ductile concrete buildings and the development of procedures for construction of unreinforced masonry buildings in economically challenged areas of the world.

Jim Gingery, Ph.D., P.E., G.E.
Chief Engineer, Keller North America
Deep Soil Mixing Design and Construction for Surface Fault Rupture Mitigation

Abstract: Deep soil mixing ground improvement was used to mitigate surface fault rupture and liquefaction hazards for a pump station with wet wells up to 36 feet deep. Paleoseismic field investigations were performed to characterize the site, then deterministic and probabilistic fault rupture displacement estimates were made and used to develop design scenarios. The fault rupture mitigation design consisted of a solid block of DSM encompassing and protecting the pump station and its wet wells. Three-dimensional soil-structure interaction numerical modeling of the fault rupture scenarios was performed as part of the design. The analyses showed the fault rupture displacements could be diverted by the DSM and that satisfactory structure performance could be achieved. The presentation concludes with an overview of the DSM construction, and quality control and assurance.

Bio: Dr. Gingery is a Chief Engineer at Keller leading a team providing ground improvement and geostructural engineering for design-build projects across the Western U.S. and beyond. Dr. Gingery holds an M.S. in geotechnical engineering from UC Berkeley and a Ph.D. in geotechnical earthquake engineering from UC San Diego. He has more than 27 years of experience in research, consulting, design, and construction, and is a license professional engineer in multiple states. In 2015, he was awarded the Shamsher Prakash Prize for Excellence in the Practice of Geotechnical Engineering.

Zeynep Gulerce, Ph.D.
Nuclear Safety Officer, International Atomic Energy Agency
The IAEA Probabilistic Fault Displacement Hazard Assessment Exercise

Abstract: IAEA Safety Standards Series No. SSR-1, Site Evaluation for Nuclear Installations, identifies fault capability as one of the potential challenges to the safety of nuclear installations. In the site selection and characterization of new nuclear installation sites, sufficient geological, geophysical, geotechnical and seismological data are obtained to demonstrate the existence of a capable fault at or near the site. Although the capable fault issues are expected to be addressed at these stages, subsequent studies may reveal that there is potentially a capable fault in the site vicinity of existing nuclear installations. For this case, IAEA Safety Standards Series No. SSG-9 (Rev. 1), Seismic Hazards in Site Evaluation for Nuclear Installations, recommends the assessment of the potential for fault displacement using probabilistic methods. In the past decade, challenges associated with the application of probabilistic fault displacement hazard analysis (PFDHA) in different tectonic settings have been recognized, and new and improved empirical fault displacement models have been published. To follow up on the recent advances in this field and for a better understanding of the PFDHA results for scenarios that may be related to nuclear installations, the IAEA designed a PFDHA exercise. This exercise aims to support the implementation of the recommendations given in SSG-9 (Rev. 1) by comparing the hazard results and interpreting the pieces of the PFDHA that contributes to the observed differences.

Bio: Zeynep Gulerce is a Nuclear Safety Officer and responsible technical officer for the IAEA Benchmarking Exercise on Probabilistic Fault Displacement Hazard Assessment. In IAEA, Ms. Gulerce is working on the tasks related to hazards from external events that may impact the safety of nuclear installations. Before taking her position in IAEA, she had worked as a full-time faculty member in Middle East Technical University and part-time consultant for the Turkish Nuclear Regulatory (NDK). Ms. Gulerce’s research efforts were focused on the state-of-the-art in seismic hazard assessment, characterization of design ground motions, and geotechnical earthquake engineering, which led to the publication of numerous scientific papers, book chapters, and technical reports. She has more than 20 years of experience in the analysis of earthquake hazards/risks, as a civil engineer working in a seismically-active country. She had provided technical consultancy to several large-scaled construction companies of Turkey, specifically on the analysis of geo-hazards for site characterization, inspection, review and assessment of hazards for defining the site parameters, and licensing procedures.

Monte Marshall, Ph.D.
Professor Emeritus, San Diego State University
The Resolution of Two Important Questions About the Nature of the San Andreas Fault

Abstract: The San Andreas fault is one of the longest and probably the most famous and well-studied strike-slip faults in the world, but geologists knew surprisingly little about it before the devastating 1906 San Francisco earthquake. In this talk, I will discuss two advances in our current understanding of this important fault: how the modern discovery of plate tectonics resolved a decades-long controversy about the very large total offset on the fault, and why a 170 km length of the fault in central California generates only minor earthquakes.

Geologists at UC Berkeley had just finished mapping the San Andreas fault from northern California south to the Imperial Valley only months before the earthquake. But they had no idea of its terrible potential. Immediately after the earthquake, the California governor authorized a state commission of geologists, mostly from UC Berkeley and Stanford, to study the fault and ground conditions responsible for the catastrophic damage and loss of lives. They were amazed when they found that the fault had slip/ground rupture that extended almost 400 kilometers. It was the longest fault rupture that had ever been recorded! They found that the slip between the two sides was usually horizontal, or “strike-slip.”

Bio: “As a fourth-generation San Diegan, I was born in Mercy Hospital in 1939. I attended St. Augustine High School, and then headed east to Philadelphia where I attended Villanova University. I majored in philosophy and minored in astronomy. Upon returning to San Diego, I enrolled at SDSU as an astronomy major. My uncle was a meteorology prof at SDSU, and at lunch he introduced me to the chairman of the geology department, Baylor Brooks. Baylor asked me if I had room in my class schedule for his intro geology class. I did, and he was such an inspiring prof and the field trips were so much fun, that I changed my major to geology and geophysics! After getting my second bachelor’s degree in 1966, I went up to Stanford for my PhD in geology and geophysics. My thesis was on the magnetic properties of seafloor basalts. The theory of plate tectonics was being debated then, and I was able to show that the one kilometer thick layer of seafloor basalt was so strongly magnetized that it was the source of the linear marine magnetic anomalies that proved plate tectonics. After grad school, I went to work in 1971 at the US Geological Survey in Menlo Park for 4 years.

“Since I really wanted to teach, as well as research, I returned to San Diego and SDSU, where I was a professor for almost 30 years. I taught courses in geophysics, structural geology, beginning geology, and paleomagnetism and plate tectonics. The research I conducted with my students was using detailed gravity surveys across the faults of metropolitan San Diego to measure their throw/vertical displacement. I also had many MS students who used the magnetization direction in cores drilled in igneous rocks to measure the tectonic rotation of the Peninsular Ranges and blocks of the Earth’s crust between the many faults in the Imperial Valley and western Arizona. I had three sabbatical years and lived, taught, and did research, at universities in France, Russia, and the Czech Republic.

“I retired in 2005 and have been busy doing geologic community service (teaching the new docents and nature hike leaders at the SD Museum of Natural History, and giving talks to various groups), and writing papers on the geologic history of the Southwest for the annual field trip guidebooks of the San Diego Association of Geologists.”

Sami Megally, Ph.D., P.E., S.E. and Keith Gazaway, P.E.
Kleinfelder
Design and Construction of the Light Rail Transit Overhead Crossing Seismic Fault Zones

Abstract: The Rose Creek LRT Overhead is a 12-span light rail bridge constructed as part of San Diego’s 11-mile Mid-Coast Corridor Transit Project. The bridge crosses the active LOSSAN rail corridor and the Rose Canyon Fault Zone, which intersects two spans and their foundations. Estimated surface rupture displacements were approximately 5 feet longitudinally and 1.2 feet vertically. A multi-disciplinary structural and geotechnical approach was used to develop a fault rupture–resilient design, incorporating detailed site investigations, soil–structure interaction modeling, and performance-based seismic criteria. The bridge was designed to prevent collapse under the maximum credible earthquake and remain operational under lower-level seismic events. Key challenges included tight clearances, maintaining railroad operations, seismic behavior of outrigger bents, and geometric complexities associated with curved precast girder spans. Construction was completed in 2020. This presentation will focus on the fault rupture design, seismic detailing, and lessons learned during construction.

Bios: Dr. Megally is a senior structural engineer with over 35 years of combined research, analysis, and design experience in reinforced and prestressed concrete structures. He has been involved in the design and construction support of several complex projects including design-build, cable-supported, steel trusses, segmental, and spliced girder bridges.

Mr. Gazaway is a senior bridge engineer with nearly 30 years of professional experience in the design, rehabilitation, and evaluation of bridges and structures in California with Kleinfelder. His experience includes project and staff management, design (new and seismic retrofit), quality control, value analysis, and preparation of plans, specifications, and cost estimates.

Karl Mueller, Ph.D.
Professor, University of Colorado, Boulder
A New Seismotectonic Framework for Active Faults in Metropolitan San Diego

Abstract: Recognition of seismic hazards in densely urbanized cities is often hampered by pervasive destruction of subtle landforms and young sedimentary deposits that geologists use to identify and characterize active faults. We overcome this challenge by using circa 1953 air photos shot prior to urbanization (i.e. < 16% of current population) to create a 2m digital elevation model of metropolitan San Diego. We extract the elevation of stratigraphic contacts from published geologic maps and ~ 100 deep boreholes to create 3D structure contour maps of Pleistocene-Eocene strata to visualize fault related folds and active faults. We enhance the subtle record of recent faulting by vertical exaggeration, narrow color bars and appropriate illumination to increase the range of tonality of 3D images. These datasets define a major new fault system that connects the active La Nacion Fault Zone (LNFZ) and Salsipuedes faults with three, newly recognized fault segments extending from Poway to Ensenada. New segments include a right lateral fault that extends the LNFZ 23 km north to Poway on Miramar NAS from a small pull apart basin in Allied Gardens, an 8 km long normal fault and linkage along the US Border, and a 15+ km right lateral fault and splays in Imperial Beach. Scarps along the border mark the trace of an active listric normal fault, or detachment that extends north of University City. Folding of the hanging wall (i.e. a rollover) above the curved detachment forming the San Diego Bay pull apart basin. Surface expression of the rollover is best defined by the south tilted flight of marine terraces south of Mission Valley. Bending moment faults at the crest of the rollover form a classic axial graben (Mission Valley) marked by faceted spurs and an offset fluvial terrace. Rollover of Eocene and Pleistocene strata across Mission Valley and Pliocene fill suggests the LNFZ slips at less than 0.5 mm/yr. The Salsipuedes fault extends north from Tijuana into Imperial Beach and the Silver Strand forming pressure ridges and down to the east faults transtensional similar to those in San Diego Bay – a southward continuation of the Rose Canyon fault to Ensenada.

Bio: Karl Mueller is a Professor of Geology at the Department of Earth Science at the University of Colorado, Boulder. A native of San Diego, Karl first earned degrees in Geology at SDSU, working on active strike slip faults and pull apart basins in Baja California. Subsequent time in the oil industry included work on gravity driven extensional structures followed by a Ph.D. on extensional tectonics. Postdoctoral work was focused on determining how blind thrust earthquakes can be identified through study of active folds in California. His work also includes determining how and why regional uplift of marine terrace platforms occurs in coastal San Diego by mantle heating and rift flank uplift in the Gulf of California. Other projects included studies of active blind thrusts in Japan, the New Madrid seismic zone, while work in Taiwan explored how erosion rearranges active faulting in a thrust belt. Dr. Mueller is currently working on developing new techniques for identifying subtle, active faults in the densely urbanized landscape of San Diego and their implications for seismic hazards.

Mike Phipps, P.G., C.E.G.
Principal Engineering Geologist, Cotton, Shires and Associates, Inc.
Fault Investigation Challenges and Issues In The Urban Setting of Santa Monica, California — A Reviewer’s Perspective

Abstract: TBD

Bio: Michael Phipps, P.G., C.E.G., is a Principal Engineering Geologist with Cotton, Shires and Associates, Inc. in Thousand Oaks, California. A Southern California native and 1987 graduate of the University of Southern California, Michael has spent the past 39 years gaining diverse technical, project management, operations management and executive experience in the geotechnical industry, predominantly in southern California. His technical expertise includes geotechnical evaluation and remediation of landslides and other geologic hazards, coastal hazard evaluation, fault hazard evaluation, engineering geological site characterization, technical/peer review for government agencies, and is a respected expert consultant/witness on litigation matters. Michael started his career working for former State Geologist and highly respected expert, the late Dr. James E. Slosson. During his 7+ years with Slosson & Associates he received a unique and well-rounded upbringing as an engineering geologist working on a variety of litigation support matters typically involving large landslides or distressed structures, performing peer review for several southern California cities, and observing large hillside mass-grading operations in a second-party role for a large residential developer in Los Angeles, Orange, Riverside, and San Diego counties. For the past two years he has been the lead engineering geological peer reviewer for emergency landslide stabilization measures for the 720-acre Greater Portuguese Bend Landslide Complex in Rancho Palos Verdes.

Over the course of his career, Michael has planned and completed multiple fault surface rupture hazard studies within the Simi-Santa Rosa Fault Zone, as well as studies on the Holser Fault, San Fernando Fault, and Stevenson Ranch zone of deformation. He has also peer reviewed over one hundred fault surface rupture hazard studies for proposed development projects in the cities of Santa Monica, Malibu, Palmdale, Simi Valley, and Moorpark, California. Michael has been a geotechnical peer reviewer for the City of Santa Monica since 2012, but more notably has been the reviewer of all fault studies conducted in the City since January 2018 when the Santa Monica Fault was zoned under the Alquist-Priolo Earthquake Fault Zoning Act.

Chris Smith and Ehsan Dezhdar
Glotman Simpson
Seismic Modelling + Performance of High-Rise Concrete Shear Wall Building Adjacent to Fault

Abstract: This study focuses on the seismic design and response of a new 37-story residential tower in San Diego, CA that sits directly adjacent to an active fault. Given the adjacent active fault, near-fault effects were extensively evaluated in the development of the ground motions and PBSD approach. GMs were developed with near-fault effects and the non-linear time history analyses (NLTHA) included simultaneous application of vertical and horizontal time series, in addition to, the permanent vertical ground displacements (VGD) associated with the fault rupture (i.e. fling-step). The ground displacement contour was idealized as a “tilting” or permanent rotation of the tower towards the fault.  Fling-step studies were performed to assess whether the VGDs associated with the fling should be applied in a static vs. dynamic fashion. Results of these studies, the PBSD evaluation criteria and GMs for this near fault are discussed herein. Incorporating vertical ground motions in NLTHA is rarely done and it presents many challenges, including but no limited to: numerical convergence, additional degrees of freedom, significant processing times, and validation of analytical results is difficult. Ground displacement effects on building structures are sometimes explored in analytical models, but rarely in the context of a NLTHA. Approaches and techniques we developed to support these highly complex analyses are discussed herein, along with our analytical results. A comparison of structural responses with two-component (horizontal GMs) and three-component (horizontal + vertical GMs) is presented. Compared to the two-component GMs, the three-component GMs are shown to have negligible effects on building drift demands and associated structural responses (i.e. rotational demands on coupling beams and outriggers, core wall flexure, and shear demands, etc.). Vertical GMs were shown to have little effect on the core wall axial-strain demands but significant effects were observed on the column axial demands. Compared to the vertical seismic effects estimated from the empirical equations per LATBSDC, NEHRP, TBI, ASCE 7, etc., we found that the vertical GMs were generating vertical seismic axial demands in the columns that were 500% to 1,000% higher than those values. Techniques developed to evaluate the columns for these unprecedented demands are discussed herein, along with the results of that evaluation.

Bios: Chris Smith, a Partner at Glotman•Simpson, is a licensed Civil and Structural Engineer with expertise in code and performance based seismic design of all building types. Chris is known for his skill in managing structural challenges in high-risk regions. He provides third-party plan checks and seismic peer reviews for various entities including the City of Los Angeles, City of San Diego, California State University, and the University of California.

Dr. Ehsan Dezhdar is a Senior Associate at Glotman•Simpson with over 15 years of experience in structural engineering, specializing in reinforced concrete design, seismic risk assessment, and displacement-based seismic design. Drawing on his doctoral research—which focused on nonlinear time history analysis of high-rise concrete shear walls—Ehsan brings deep technical insight to the performance-based design of towers, particularly in high seismic regions like California.

Ehsan plays a key role in advancing innovative seismic solutions within our team, contributing to the design of resilient, code-exceeding buildings. He has presented his work at leading international conferences on earthquake engineering, reinforcing his commitment to bridging research and practice to better inform the built environment.

Nick Oettle, Ph.D., P.E., G.E.
Senior Consultant, GEI Consultants, Inc.
Designing Infrastructure for Surface Fault Rupture

Abstract: Recent earthquakes have provided numerous examples of the effects of earthquake surface fault rupture on structures, including from the 2025 Myanmar Earthquake when the first video ever of surface fault rupture was recorded. Because of the often-unavoidable nature of surface faults, infrastructure must sometimes be constructed near surface faults. This presentation will focus on the latest developments in designing infrastructure for surface fault rupture. Included will be observations from actual surface fault rupture effects on infrastructure, mitigation strategies for designing against surface fault rupture, and numerical modeling analysis techniques that have been recently developed and validated with centrifuge testing. Typical requirements for buildings and dams will be presented, including recommendations from a newly formed working group on incorporating surface fault rupture requirements into the building code.

Bio: Nick Oettle is a Senior Consultant with 18 years of experience in geotechnical earthquake engineering. His project experience includes managing large dam and water infrastructure projects, focusing on earthquake engineering, seismic risk, and numerical modeling. Nick has been involved with the USSD earthquakes committee, the development of ASCE 7-22 and 7-28, traveled to Japan as a member of the GEER reconnaissance team for the 2016 Kumamoto Earthquake, and has authored over 30 technical publications. He earned his Ph.D. in Geotechnical Earthquake Engineering from UC Berkeley developing numerical modeling techniques for surface fault rupture interaction with structures. Recently, he has led a working group to add surface fault rupture provisions to the building code.

One-Day Short Course

Dr. Rui Chen, California Geological Survey
Alexandra Sarmiento, P.E., P.G., CEG | GeoPentech, Inc.; University of California, Los Angeles
Dr. Stephen Thompson, Lettis Consultants International, Inc.

Friday, August 22nd, 2025, 8:30am-3:30pm
University of California, San Diego
Franklin Antonio Hall 1301

The second day of the 7th Kenji Ishihara Colloquium Series on Earthquake Engineering, cohosted with EERI UCSD, will be a workshop focused on advances in Probabilistic Fault Displacement Hazard Analysis (PFDHA), featuring expert-led sessions on recent initiatives, computational tools, and practical applications. Presentations provide attendees with a comprehensive overview of current methods and emerging approaches, complemented by real-world application examples.

Click the image on the right to view the event flyer.
Click here to go to Day 1 of the 7th Kenji Ishihara Colloquium Series.

ABSTRACTS

Fault Displacement Hazard Initiative (FDHI) Program Overview, Scenario-Based FDHA Computational Tools
Alexandra Sarmiento and Yousef Bozorgnia
The Fault Displacement Hazard Initiative (FDHI) Project is a community-based research program that was established to advance the state-of-practice in fault displacement hazard analysis (FDHA). Toward this end, a comprehensive and standardized database of fault displacement measurements, surface rupture maps, and supporting information from 75 historical, surface-rupturing earthquakes was created. Four new fault displacement models (FDMs) providing probability distributions for surface fault displacement were developed using the new database. The results from this first phase of the FDHI Project are published in Earthquake Spectra‘s “Fault Displacement Hazard Analysis Special Collection.” The new models are implemented in a publicly available Python package and Excel workbook.

Probabilistic Fault Displacement Hazard Analysis (PFDHA) – An Overview
Dr. Rui Chen
Fault displacement hazard analysis (FDHA) provides quantitative estimates of surface fault displacement from future earthquakes —critical for the safe design of infrastructure that crosses or lies near active faults. This presentation reviews the fundamentals of FDHA and briefly compares its two primary methodologies: deterministic FDHA and probabilistic FDHA (PFDHA). The focus of this presentation is on PFDHA, which extends the methodology of probabilistic seismic hazard analysis by replacing ground motion models with fault displacement models and incorporating additional probabilistic elements to account for the occurrence of surface rupture (i.e., the earthquake approach). Key components of the PFDHA framework are outlined, and their integration is demonstrated through an open-access Fortran implementation, accompanied by example results. While the presentation centers on principal displacement, distributed displacement is also briefly discussed. The talk further highlights evolving building code requirements, emerging national and international guidance, and ongoing research efforts to advance PFDHA.

Fault Displacement Hazard Analysis Example Applications
Dr. Stephen Thompson
This talk will review key components of fault displacement hazard analysis for the evaluation of design and/or seismic safety of various types of infrastructure, including both lifelines (gas and water pipelines, rail lines) and structures with fixed footprints (dams, buildings). Uncertainty in the location of active faults has been and will continue to be the most vital part of the hazard assessment for most projects. Aside from the mantra of location, location, location, the talk will provide a series of example applications for both principal and distributed displacement hazard that will discuss the implementation of published models for PFDHA, common mistakes or misconceptions we have observed, which model components dominate the uncertainty in hazard, and how logic trees can (and should) incorporate epistemic uncertainties that go beyond the currently available published models. The talk will also provide some suggestions—and hopefully generate some discussion—about how to communicate the results of a PFDHA to aid in decision making.

MEET THE INSTRUCTORS

Dr. Rui Chen

Rui Chen is a Senior Seismologist with the California Geological Survey (CGS), where she has served since 2008. Her expertise includes ground motion hazard analysis to support CGS’ regulatory liquefaction and earthquake induced landslide hazard mapping program, as well as the review of geotechnical investigations for critical facilities such as hospitals, schools, and nuclear installations. She conducts research on probabilistic fault displacement hazard analysis, including the development of fault displacement and rupture probability models. She also contributes to statewide earthquake shaking potential maps and earthquake loss estimation for California. Rui Chen holds a Ph.D. in Civil and Geological Engineering from the University of Manitoba, Canada, and M.S. and B.S. degrees in earthquake sciences from institutions in China. She is a licensed Professional Engineering Geologist in California and has over three decades of experience in academia, consulting, and applied geosciences.

Alexandra Sarmiento

Alexandra Sarmiento is a seismic hazard analyst at GeoPentech, Inc. and a researcher at the University of California, Los Angeles (UCLA) with 15 years of experience in consulting practice and academia. Her expertise includes seismic source characterization, ground motion hazard analysis, ground motion development, and fault rupture and displacement hazard analysis. Alexandra is part of the Fault Displacement Hazard Initiative (FDHI) research project at UCLA, where she led the development of a new, high-quality database of mapped surface ruptures and fault displacement measurements. She also led a comprehensive technical comparison of new and existing fault displacement models. Alexandra has B.S. and M.S. degrees in Geological Engineering and Geology, respectively, from the University of Nevada, Reno and is registered in California as a Professional Engineer, Professional Geologist, and Certified Engineering Geologist.

Dr. Stephen Thompson

Stephen Thompson is a Senior Principal Engineering Geologist at Lettis Consultants International, Inc. (LCI) where he specializes in the characterization of active faults for hazard evaluation. Since completing his PhD in Geological Sciences at the University of Washington in 2001, Steve has been trying to provide clients and colleagues with useful information to help quantify and mitigate the hazards of surface-fault rupture and strong ground shaking. Steve spends much of his time trying not to be overwhelmed by the uncertainties—real and imagined—involved in fault source characterization for seismic hazard analysis (PSHA and DSHA) and fault displacement hazard analysis (PFDHA and DFDHA). Being able to effectively communicate with engineers keeps him up at night.

PROGRAM

Moderator: Taylor M. Gater, P.E. | GeoEngineers, Inc. || EERI San Diego Chapter Director of Events

VENUE
University of California, San Diego
Franklin Antonio Hall 1301
3180 Voigt Drive
La Jolla, CA 92093

REGISTRATION
Click here to register for the colloquium. Registration closes on Monday 8/18 at 11:59pm.

LODGING
Click here for a list of hotels near UCSD.

PARKING
For $8 per day, conference parking permits are available in advance through UCSD’s Parking Portal website, which you can access by clicking here. In order to purchase a parking permit, you will need to create an account. When you click on the aforementioned link, it should show a “Guest User Registration” form. Otherwise, click on “SIGNUP” in the upper right corner of the webpage. Once you fill out the form and create an account, follow the prompts to purchase your conference parking permit for the days you will be attending the colloquium.

You can also pay for parking through the ParkMobile app or website the day-of the colloquium. More information can be found here.

There are two structures available for parking near Franklin Antonio Hall: Hopkins and Pangea. The closest parking structure to the venue is Hopkins Parking Structure (view here or here), located on Voigt Dr. off of Hopkins Dr. If Hopkins is full, please go to Pangea Parking Structure (view here or here), located on Pangea Dr. off of N. Torrey Pines Rd. You may only park in B-spaces with your pre-purchased conference parking permit.

Click image below to see the parking structures and venue highlighted (from https://maps.ucsd.edu/map/default.htm):

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