Meeting Abstracts | Southern California Earthquake Center

SCEC2021 Meeting Abstracts

SCEC Annual Meeting participants are invited to share recent results and activities relevant to SCEC priorities and initiatives during the poster sessions. The SCEC collaboration emphasizes the connections between information gathering by sensor networks, fieldwork, and laboratory experiments; knowledge formulation through physics-based, system-level modeling; improved understanding of seismic hazard; and actions to reduce earthquake risk and promote resilience.

Use the search form to view abstracts of presentations that have been accepted for this meeting.

Results 1-50 of 292

SCEC ID	Category	Title and Authors	SCEC Award
Poster 009	CXM	The USGS San Francisco Bay region 3D seismic velocity model (SF-CVM) version 21.1.0: Updates for the East and North Bay and a new storage scheme for 3D Earth models Brad Aagaard, Evan Hirakawa Version 21.1.0 of the USGS San Francisco Bay Region 3D Seismic Velocity Model (SF-CVM) updates regions east and north of the San Francisco Bay and uses an improved storage scheme and query interface. This latest version revises version 08.3.0 (... more
Poster 155	FARM	Advanced Earthquake Cycle Simulations: Bimaterial Interfaces, LVFZ, and nonlinear bulk rheology Mohamed Abdelmeguid, Ahmed Elbanna Modeling earthquake ruptures is a complex challenge due to the eclectic sources of nonlinearities and heterogeneities, in addition to the multi-scale nature of the problem, both spatially and temporally. In this study, we utilize FEBE and efficient... more
Poster 243	Seismology	Brune stress drop, fault slip distribution and high frequency radiation during the 2016-2018 Amatrice-Visso-Norcia seismic sequence Rachel Abercrombie, Giovanna Calderoni The predominantly normal-faulting sequence of earthquakes in the Appenines of central Italy during 2016-2018 included nine Mw > 5 earthquakes. Multiple researchers (e.g., Bindi et al., 2020; Morasca et al., 2019) have estimated Brune-style stress... more
Poster 108	Geodesy	Spatiotemporal variations of stress and strain in the crust near 2019 Ridgecrest Sequence Earthquakes Niloufar Abolfathian, Eric Fielding, David Bekaert, Andrea Donnellan, Simran Sangha Recent advances in data acquisition, analysis methods, and computational capabilities allow spatiotemporal estimations of stress and strain in high-resolution within the Earth’s crust. We analyze the interferometric synthetic aperture radar (InSAR)... more
Poster 065	Geology	Pre and post rupture Fault Mapping Comparisons applications to Probabilistic Fault Displacement Hazard Rachel Adam, Joseph Powell, John Ford, Chelsea Scott, Ramon Arrowsmith Pre- and post- earthquake fault maps inform Probabilistic Fault Displacement Hazard Assessment (PFDHA) to anticipate locations and other characteristics of coseismic ruptures. Our goal is to create pre-rupture fault maps for a series of recent... more
Poster 072	Geology	Surficial fractures from the middle of the 2019 Ridgecrest mainshock mapped from high-resolution aerial imagery Brian Aguilar, Alba Rodriguez Padilla, Mercedes Quintana, Thomas Shea, Michael Oskin The surface deformation field of an earthquake contains information about rupture propagation and fault geometry. The 2019 Ridgecrest Earthquake sequence caused a surface rupture that was documented by 5cm resolution aerial imagery collected by the... more
Poster 012	CXM	Beyond 1 Hz: Double-difference active source adjoint tomography of Salton Trough Rasheed Ajala, Patricia Persaud, Alan Juarez A decade after the Salton Seismic Imaging Project (SSIP), we have initiated the overdue high-frequency adjoint tomography of Salton Trough crust. We are mainly motivated by previous results showing that embedding 3D travel time Earth models... more	18074, 19014, 20023, 21059
Talk 13-Sep (11:00)	Seismology	Exploring The Subsurface with Regional DAS Networks: Results from the Imperial Valley Dark Fiber Project Jonathan Ajo-Franklin, Veronica Rodriguez-Tribaldos, Patrick Dobson, Avinash Nayak, Feng Cheng, Benxin Chi, Todd Wood, Michelle Robertson, Rob Mellors, Cody Rotermund, Bin Dong, John Wu, Christina Morency, Dennise Templeton, Eric Matzel Recent studies by several research groups have conclusively demonstrated that existing telecommunication infrastructure can be effectively paired with Distributed Acoustic Sensing (DAS) to provide high-density broad band recordings at 10s of km... more
Poster 090	SAFS	Multidisciplinary investigation of determining channel incision ages in the Carrizo Plain, California. Sinan Akciz, Matthew Kirby Offset channels are routinely used to determine slip rates and slip-per-earthquake measurements. Plots showing the distribution of slip along the strike of a fault are used to infer the slip distribution during previous earthquakes and even... more	19170
Poster 128	FARM	Very long timescale of grain size and shear zone evolution in a continental strike-slip setting Kali Allison, Laurent Montesi Understanding the mechanical interaction between brittle faults and deeper ductile shear zones provides insights into the long-term behavior of active fault systems. We explore this interaction in a 2D model of a continental strike-slip fault zone.... more	20191
Poster 127	FARM	Using Active Source Seismology to Image a Strike-Slip Fault Damage Zone as a Function of Depth, Distance, and Geology Travis Alongi, Emily Brodsky, Jared Kluesner, Daniel Brothers Fault damage zones provide a window into the non-elastic processes and products of an earthquake, but geological and seismic tomography methods have limited resolution and in particular have been unable to measure damage zones at depth with... more	21182
Poster 116	SDOT	New initiative to examine the impacts of oil and gas operations on fault stability and earthquake processes in the Los Angeles basin, CA Josimar Alves da Silva, Franklin Wolfe, Annika Huprikar, Andreas Plesch, Ruben Juanes, John Shaw We have initiated a new effort to explore how nearly a century of oil and gas production and associated wastewater injection have impacted the state of stress on tectonically active faults in the Los Angeles basin. We begin with a study of the... more
Poster 194	Seismology	Ambient noise monitoring of stress-induced seismic velocity changes associated with the 2019 Ridgecrest earthquake sequence Yanru An, Taka'aki Taira An improved understanding of the stress field in the seismogenic crust is central to studies of earthquake physics and its spatial variations will provide crucial observational insights into the faulting processes. The 2019 Ridgecrest earthquake... more
Poster 091	SAFS	Estimating tractions along the San Andreas and San Jacinto faults prior to ground-rupturing earthquakes of the last four centuries Emery Anderson-Merritt, Michele Cooke Understanding the state of stress in a fault system prior to previous ground-rupturing earthquakes can help us understand the conditions that generate these events and constrain initial conditions for dynamic rupture models of large earthquakes. We... more
Poster 106	Geodesy	Using optical image correlation to quantify the three-dimensional displacement field of historical events: Example from the 1959 Mw 7.2 Hebgen Lake earthquake. Lucia Andreuttiova, James Hollingsworth, Pieter Vermeesch, Thomas Mitchell, Eric Bergman Optical image correlation has been previously used to retrieve the ground displacement caused by recent earthquakes. However, applying this method to historical ruptures can be challenging because historical aerial photographs may be affected by... more
Poster 074	Geology	Back-limb and fore-limb folding of the Puente Hills blind-thrust fault with implications for late Pleistocene slip-rate estimates and seismic hazard analysis in the Los Angeles Basin, southern California Chris Anthonissen, Franklin Wolfe, Lorraine Leon, Jessica Don, James Dolan, John Shaw, Tammy Rittenour, Ed Rhodes, Andrew Ivester We used a combination of high-resolution and industry seismic reflection profiles, historical well logging data, and luminescence and 14C ages to determine a detailed, late Pleistocene to present-day incremental slip rate record for the Santa Fe... more
Poster 088	SAFS	Constraining long-term sediment depositional history at ancient Lake Cahuilla, Coachella, California Marina Argueta, Sourav Saha, Seulgi Moon, Nathan Brown, Thomas Rockwell, Katherine Scharer, Zoe Morgan, Jenifer Leidelmeijer The depositional history of the Salton Sea region provides a rich framework for understanding the timing of paleoearthquakes along the southern San Andreas fault and the lake level history of Lake Cahuilla (LC). Previous trenching investigations... more	21100, 20144
Poster 138	FARM	Comparison of zircon (U-Th)/He and biomarker analyses to quantify coseismic temperature rise along the Punchbowl fault, CA Emma Armstrong, Alexis Ault, Kelly Bradbury, Heather Savage, Stuart Thomson, Pratigya Polissar During an earthquake, work done to overcome fault friction is dissipated as heat. However, coseismic temperature rise, critical for identifying past earthquakes, is difficult to accurately quantify in the rock record. To address this issue we... more	20153
Poster 040	GM	2D Refraction Microtremor Analysis of SW4 Synthetics Chelsey Assor, Jenna Graham, Lauren Lewright, Aditya Prathap, John Louie Geotechnical measurements of shear-wave velocity currently rely on one-dimensional surface-wave dispersion analyses. Such analyses do not account for 3D wave propagation across lateral velocity heterogeneities. Pancha and others, as an example, used... more
Poster 201	Seismology	Bayesian framework for inversion of second-order stress glut moments James Atterholt, Zachary Ross We present a fully Bayesian inverse scheme to determine second moments of the stress glut using teleseismic earthquake seismograms. The second moments form a low-dimensional, physically-motivated representation of the rupture process that captures... more
Talk 14-Sep (08:00)	Geology	What can hematite (U-Th)/He thermochronometry tell us about fault mechanics in the shallow crust? Alexis Ault Above the seismogenic zone, earthquake ruptures may propagate to the surface along discrete fault planes or earthquake energy is attenuated in fault damage zones. Forecasting earthquake hazards requires knowledge of the slip distribution and... more	21068, 17164, 14125
Poster 153	FARM	The effects of temperature and pressure on thermal pressurization in localized fault zones Nir Badt, Terry Tullis, Greg Hirth, Christian Huber Thermal pressurization (TP) of pore fluids is predicted to be a dominant frictional weakening mechanism during earthquakes. The current prevailing models for frictional sliding with TP assume constant hydraulic and thermal properties (e.g.,... more	20127
Poster 034	GM	3D Modeling of the Kathmandu Basin Effects on Ground Motions for the 2015 Gorkha earthquake Amrit Bal, Alice-Agnes Gabriel, Thomas Ulrich The 2015 Mw7.8 Gorkha earthquake unzipped a locked portion of the Main Himalayan Thrust, which caused nearly 9000 fatalities across Nepal. However, the damage was less severe in Kathmandu when compared to empirical hazard estimates, particularly... more
Poster 195	Seismology	Introduction to the SCEC Community Stress Drop Validation Study TAG Annemarie Baltay, Rachel Abercrombie, Taka'aki Taira We introduce a community stress drop validation study using the 2019 Ridgecrest earthquake sequence, in which researchers are invited to use a common dataset to estimate earthquake stress drop. Earthquake stress drop is a key parameter in many... more	21083
Poster 171	FARM	Investigating the influence of mm-scale contact processes on dynamic weakening in high-speed rock friction experiments Monica Barbery, Frederick Chester, Judith Chester Dynamic weakening due to flash heating arises from asperity-scale processes during seismic slip, however processes at the mm-scale and larger may contribute to the total weakening and help resolve transient and hysteretic friction observed in... more	21095
Poster 262	EFP	Pseudo-prospective testing of five year time-independent California earthquake forecasts with inlabru Kirsty Bayliss, Mark Naylor, Farnaz Kamranzad, Ian Main Probabilistic forecasts estimate the likelihood of future seismicity in some specified time-space-magnitude window, but a forecast can only truly be considered meaningful if it demonstrates a degree of proficiency at describing future seismicity.... more
Poster 264	EFP	Are regionally calibrated earthquake forecast models more informative than global models? First results from California and Italy José Bayona, William Savran, Maximilian Werner Earthquake forecasting models formalize critical hypotheses about seismogenesis that can support regional and global seismic hazard assessments. Regional models provide detailed seismicity forecasts due to the increasing availability of high-... more
Poster 146	FARM	Dynamic Interactions Between the Southern San Andreas Fault and Normal Faults in the Brawley Seismic Zone LUIS BAZAN FLORES, Christodoulos Kyriakopoulos, David Oglesby, Aron Meltzner, Thomas Rockwell, John Fletcher In this work, we investigate the initiation phase and subsequent triggering of the Southern San Andreas Faut (SSAF) by adjacent smaller faults that could serve as nucleation points and/or participate in larger multi-fault ruptures. Our target area... more
Poster 113	SDOT	Tectonic inheritance during plate boundary evolution in southern California constrained from seismic anisotropy Thorsten Becker, Vera Schulte-Pelkum, Whitney Behr, Meghan Miller The style of convective force transmission to plates and strain-localization within and underneath plate boundaries remain debated. To address some of the related issues, we analyze a range of deformation indicators in southern California from the... more	18083, 15059, 14026
Poster 078	Geology	INVESTIGATING THE STRUCTURE OF THE ‘SAND HILLS FAULT’ THROUGH DIFFUSE CO2 DEGASSING MEASUREMENTS Alexander Berne, Joann Stock Carbon Dioxide (CO2 ) is continuously discharged from volcanic systems with shallow subsurface magma chambers (Irwin and Barnes, JGR,1980). In these regions, faulted rock exhibits a higher permeability than surrounding country rock and can act as a... more
Poster 094	SAFS	Fault-zone gas venting and aseismic slip: ventilation or lubrication? Roger Bilham, John Langbein, Todd Ericksen, Johanna Nevitt, Benjamin Brooks, David Mencin In the days following the February 2020 Mw 6.7 Sivrice earthquake, a 2-km-length of the East Anatolian fault beneath the Euphrates River was observed to vent gasses that formed distinct en-echelon lines of bubbles above the surface rupture. One... more
Poster 189	Seismology	Ambient noise cross-correlation precursor imaging using dense seismic arrays Ettore Biondi, Jorge Castellanos, Robert Clayton Non-uniform noise source distributions are common whenever seismic stations record data in proximity of a continental coast (Stehly et al., 2006). When seismic data in these areas are used to compute noise cross-correlations, it is possible to... more
Poster 097	Geodesy	Geodetic Data, Data Products and Displacement Time Series Portal Yehuda Bock, Angelyn Moore, Peng Fang, Dorian Golriz, Donald Argus, Zhen Liu, Katherine Guns, Xiaohua Xu, David Sandwell, Anne Sullivan, Songnian Jiang, Alistair Knox Our NASA MEaSUREs project “Extended Solid Earth Science ESDR System” (ES3) is a long-lived collaboration of JPL and SIO. Using independent software packages, GipsyX Network Processor and GAMIT/GLOBK and a common source metadata at SOPAC to process... more
Poster 160	FARM	Microstructural Controls on Mixed Mode Dynamic Fracture Propagation in Crystalline and Porous Sedimentary Rocks Michael Braunagel, William Griffith The growth and interaction of fractures in fault damage zones plays an important role in earthquake rupture propagation. However, crack propagation in rocks is a complex process due to grain-scale heterogeneity and rapidly evolving stress states... more
Poster 030	GM	Comparison of Depth-to-Bedrock with VS30 and Terrain Classes, Including Implications for Predicting Dominate Site Frequencies (fd) Elizabeth Brown, Alan Yong Local geologic conditions can strongly influence seismic responses that are due to subsurface stiffness and resonance effects of a site. Depth-to-Bedrock (DtB)—known to directly affect site resonance frequencies—is an important site parameter but is... more
Poster 056	Geology	Assessment of the paleoseismic potential of the Ferrum site along the southernmost San Andreas fault using new UAV imagery, GPR data, and preliminary trenching William Buckley, Thomas Rockwell, Katherine Scharer, Allen Gontz, Paula Figueiredo, Zoe Morgan We initiated studies along the southern San Andreas fault at Ferrum, CA, where a double releasing bend has ponded Holocene alluvium against an uphill-facing scarp. Ferrum is located along the east side of the Salton Sea between Bombay Beach and... more
Poster 080	Geology	Geomorphic Indicators of Neotectonic Activity along the Santa Ynez fault, in Santa Barbara County, CA Faith Burkett The Santa Ynez Fault (SYF) is located on the northern edge of the western Transverse Ranges (WTR) in southern California. Past studies have interpreted reverse and left-lateral offset along the SYF based on the displacement of Miocene and older... more
Poster 039	GM	Verification of the broadband CyberShake platform Scott Callaghan, Christine Goulet, Fabio Silva, Philip Maechling, Robert Graves, Ossian O'Reilly, Kim Olsen, Te-Yang Yeh, Albert Kottke, Yehuda Ben-Zion SCEC has developed the CyberShake software platform to implement a physics-based probabilistic seismic hazard analysis (PSHA) approach using 3D wave propagation simulations to calculate seismograms and ground motions from sources defined in regional... more
Poster 204	Seismology	Correlation between Aλ fault parameter and statistical frequency of earthquakes along depth: a case study in Southern California Andrea Carducci, Antonio Petruccelli, Angelo De Santis, Rita de Nardis, Giusy Lavecchia Using a relocated earthquake catalog and focal mechanisms from Southern California, we investigated a connection between statistical frequency-magnitude relation from Gutenberg-Richter equation, also known as b-value and Aλ: this is a quantification... more
Poster 141	FARM	Role of background stress state in fluid induced aseismic slip and dynamic rupture on a 3 meter laboratory fault Sara Cebry, Chun-Yu Ke, Gregory McLaskey Fluid injection for oil and gas operations, CO2 sequestration, or enhanced geothermal systems (EGS) stimulates seismicity far from active tectonic regions however, the details of how propagating fluid causes stress changes and potentially triggers... more
Poster 190	Seismology	Quantifying earthquake source parameter uncertainties associated with local site effects using a dense array Hilary Chang, Rachel Abercrombie, Nori Nakata, Colin Pennington, Kilian Kemna, Elizabeth Cochran, Rebecca Harrington We investigate the influence of local site effects on earthquake source parameter estimates using the LArge-n Seismic Survey in Oklahoma (LASSO). The LASSO array consisted of 1825 stations in a 25 km x 32 km region with extensive wastewater... more
Poster 228	Seismology	Discovery of Offshore Very Low Frequency Earthquakes in the Cascadia Kuntal Chaudhuri, Abhijit Ghosh Cascadia subduction zone is one of the most complicated plate boundaries. Significant amount of stress in this subduction zone is released due to ETS in the form of tremors, low frequency earthquakes (LFE), and onshore very low frequency earthquakes... more
Poster 027	CS	Evaluating Seismic Hazard Using Large Scale Ground Motion Simulations Mary Chen, Christopher Tobar, Alexander Breuer Large-scale ground motion simulations offer an alternative to evaluate seismic hazards, reducing the reliance on isolated empirical data. These simulations require the integration of field data with the complex computational software. Large extents... more
Poster 021	CS	Virtual Shake Robot: Dynamics Simulation of Precariously Balanced Rocks for Hazard Analysis Zhiang Chen, Devin Keating, Jnaneshwar Das, Christine Wittich, Ramon Arrowsmith Physical shake tables have been used to study fragility of Precariously Balanced Rocks (PBRs) and other structures. These analyses are critical to reduce uncertainties in probabilistic seismic hazard analysis (PSHA) models. With recent developments... more	21137
Poster 103	Geodesy	Power-law viscoelastic flow of the lower Makran accretionary prism following the 2013 Baluchistan earthquake Guo Cheng, William Barnhart Accretionary prism is alternatively treated as an elastic, Coulomb prism or a system where permanent deformation is accommodated by faulting and folding of otherwise elastic materials. Recent geodetic observations of post-seismic surface deformation... more
Poster 114	SDOT	A Refined Comprehensive Earthquake Focal Mechanism Catalog for Southern California Derived with Deep Learning Algorithms Yifang Cheng, Zachary Ross, Egill Hauksson, Yehuda Ben-Zion Earthquake focal mechanisms are primary data for analyzing fault zone geometry, sense of slip, and the crustal stress field. Solving for the focal mechanisms of small earthquakes is challenging because phase arrivals and first-motions are hard to... more	20042
Poster 238	Seismology	Fault interactions enhance high-frequency earthquake radiation Shanna Chu, Victor Tsai, Daniel Trugman, Greg Hirth Fault complexity has been linked to high-frequency earthquake radiation, although the underlying physical mechanisms are not well understood. Fault complexity is commonly modeled with rough single faults; however, real-world faults are additionally... more
Poster 248	Seismology	Optimizing alerts by tuning the PLUM prediction radius for the ShakeAlert System Elizabeth Cochran, Jessie Saunders, Sarah Minson, Julian Bunn, Debi Kilb, Annemarie Baltay, Colin O'Rourke, Mitsuyuki Hoshiba, Yuki Kodera We optimize performance of the Propagation of Locally Undamped Motion (PLUM) Earthquake Early Warning (EEW) algorithm in the U.S. ShakeAlert System by testing a range of distances used to forecast ground motions. EEW systems, such as ShakeAlert,... more
Poster 184	Seismology	Using foreshocks, aftershocks and sequences to probe earthquake nucleation Rebecca Colquhoun, Jessica Hawthorne If earthquake nucleation is governed by single-mode triggering, a series of earthquakes occur, each triggering another event, one of which happens to grow much bigger. In this process, nucleation of each earthquake is rapid. However, nucleation may... more
Poster 142	FARM	Stress transfer and fault geometry's influence on the 2019 Ridgecrest Earthquake slip distribution Jordan Cortez, Christodoulos Kyriakopoulos, Baoning Wu, David Oglesby, Roby Douilly, Kuntal Chadhuri, Abhijit Ghosh Stress transfer from long-term loading as well as prior earthquakes can lead to seismic triggering and strongly affect subsequent rupture propagation and slip patterns in a fault system. A prime example of this effect is the 2019 Ridgecrest... more

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