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 201-250 of 292

SCEC ID	Category	Title and Authors	SCEC Award
Poster 118	SDOT	Mesozoic Fabric Inheritance in the Ductile Roots of the Quaternary Cucamonga Fault Francine Robles, Omid Arzili, Joshua Schwartz, Elena Miranda, Keith Klepeis, Gabriela Mora-Klepeis The geologic framework of Southern California is superimposed upon blocks of basement rocks containing inherited ductile fabrics, including Late Cretaceous mylonite, which function as stress guides for strain localization along major, recently... more	21140
Poster 082	Geology	New age data constrain the recurrence interval on the Whittier fault Thomas Rockwell, Sinan Akciz, Eldon Gath The Whittier Fault zone, the northern continuation of the NW-trending Elsinore Fault, extends from south of Santa Ana Canyon, where it splits off of the Chino Fault, to Whittier Narrows in Los Angeles County on the northwest. Based on geological... more	20194
Poster 010	CXM	Adjoint Waveform Tomography of the Crust and Uppermost Mantle of the Western United States for Improved Waveform Simulations and Source Characterization Arthur Rodgers, Claire Doody, Andrea Chiang, Lion Krischer, Christian Boehm, Michael Afanasiev, Nathan Simmons We are developing a model of three-dimensional radially anisotropic seismic structure of the crust and uppermost mantle of the Western United States (WUS) with adjoint waveform tomography. This region spans the diverse geologic/tectonic regions from... more
Poster 115	SDOT	A Curvature-based Approach to Measuring Permanent Long-wavelength Off-fault Deformation: Applications to the Volcanic Tablelands, CA Alba Rodriguez Padilla, Michael Oskin Detailed and continuous geomorphic measurements of permanent off-fault deformation accrued over geologic timescales are challenging to collect due to incomplete knowledge of the pre-faulted landscape, sparse data coverage, erosion, and limited... more	19209
Poster 077	Geology	Preliminary Mapping of Surface Fault Rupture and Ground-Deformation Features of the 2019 M6.4 and M7.1 Ridgecrest Earthquake Sequence from Post-Earthquake Lidar and Orthoimagery Datasets Carla Rosa, Reva Kakaria, Timothy Dawson We present preliminary mapping of surface ruptures and ground-deformation features associated with the 2019 Ridgecrest Earthquake Sequence. The mapping utilizes high-resolution airborne lidar and orthoimagery acquired post-earthquake by the National... more
Poster 180	Seismology	Evidence for Latent Crustal Fluid Injection Transients in Southern California From Long-Duration Earthquake Swarms Zachary Ross, Elizabeth Cochran Earthquake swarms are manifestations of aseismic driving processes deep in the crust. We examine the spatiotemporal distribution of aseismic processes in Southern California using a 12-years catalog of swarms derived with deep learning algorithms.... more
Poster 050	GM	Verification of Iwan-type Plasticity in the Discontinuous-Mesh GPU-powered Wave Propagation Code AWP Daniel Roten, Kim Olsen, Steven Day, Yifeng Cui The hysteretic stress-strain relationship of the shallow crust and its effects on strong ground motions and fault zone deformation represents one of SCEC’s research priorities and is the focus of a technical activity group. Using funding from SCEC... more	20166
Poster 173	FARM	Experimental study of frictional shear resistance under rapid variations of normal stress and near-field ground motion of thrust earthquakes Vito Rubino, Yuval Tal, Ares Rosakis, Nadia Lapusta A proper formulation for the evolution of shear resistance during rapid changes in normal stress is essential for many earthquake source problems. While the shear resistance is typically assumed to be proportional to normal stress, several studies... more	21088
Poster 230	Seismology	Can Fault-Zone Complexity Explain Spatiotemporal Variation in Observed Stress Drops? Christine Ruhl, Rachel Abercrombie, Peter Shearer High-resolution studies of earthquake stress drops have yielded significant scatter, often with orders of magnitude of variation seen on very small spatial and temporal scales. Understanding whether stress drop depends on hypocenter depth, fault... more
Talk 14-Sep (08:00)	Geology	Potentials and challenges with single-grain luminescence dating—re-evaluating our assumptions Sourav Saha, Seulgi Moon, Nathan Brown, Ed Rhodes, Sally McGill The luminescence signals in quartz grains from tectonically active regions, such as Southern California, are usually dim. This precludes us from dating single-grain quartz luminescence from these regions. The K-feldspar samples are usually brighter... more	21100
Poster 105	Geodesy	Estimating geodetic locking depth and long-term slip rate along the central San Andreas Fault using Neural Networks Shaparak Salek, Eileen Evans Geodetic observations, such as from the Global Navigation Satellite System (GNSS), record deformation of the Earth’s crust due to strain accumulation on locked faults. Along a vertical strike-slip fault such as the San Andreas Fault, a geodetically... more
Poster 102	Geodesy	The distribution of shallow creep on active faults in California, from a deformation velocity field derived from Sentinel-1 ARIA standard product interferograms Simran Sangha, Gareth Funning, David Bekaert The launch of Sentinel-1A in 2014 heralded an era of temporally dense SAR data coverage over tectonically active areas, such as the plate boundary fault system in California. The JPL/Caltech ARIA system is an effort to operationalize InSAR... more	20177
Poster 037	GM	A Twist of PLUM: Low-Magnitude Earthquakes and Ground-Motion-Based Early Warning Jessie Saunders, Sarah Minson, Elizabeth Cochran, Julian Bunn, Annemarie Baltay, Debi Kilb, Colin O'Rourke We examine the earthquake detection and alerting behavior of the Propagation of Local Undamped Motion (PLUM) earthquake early warning (EEW) algorithm as applied to real-time data in 2021 from U.S. West Coast earthquakes. PLUM uses observations of... more
Poster 263	EFP	Reproducible earthquake forecasting experiments with pyCSEP William Savran, José Bayona, Maximilian Werner, Philip Maechling An important goal of the Collaboratory for the Study of Earthquake Predictability (CSEP) is to facilitate transparent and reproducible earthquake forecasting experiments. To reproduce an experiment, we must obtain consistent results, at least... more	20076
Poster 111	SDOT	Multifractal analysis of a seismic moment distribution obtained from InSAR inversion Cameron Saylor, John Rundle Interferometric synthetic-aperture radar (InSAR) interferograms are a valuable tool that can tell us about the fault systems hidden beneath the surface of the Earth. In a new approach, we fit InSAR ground deformation data using a distribution of... more
Poster 059	Geology	Impact of fires, earthquakes, and climate on catchment response since 600 CE, Pallett Creek, San Gabriel Mountains, California USA Katherine Scharer, Jenifer Leidelmeijer, Matthew Kirby, Nicole Bonuso, Devin McPhillips In tectonically active regions, sedimentary records are overprinted by landscape response to climate, fire, and local earthquakes. We explore this issue using a new paleoclimate record developed at the Pallett Creek paleoseismic site in southern... more
Poster 068	Geology	Investigating the Simi-Santa Rosa fault with pre-development high-resolution topography Brian Schrotenboer, Reed Burgette, Katherine Scharer The Simi-Santa Rosa fault (SSRF) bounds the northern edge of the Simi Valley basin in the Western Transverse Ranges, California. GPS velocities measured across this part of the Transverse Ranges show ~6-7 mm/yr of crustal shortening, thought to be... more	21147
Poster 006	CXM	Synthesis of fault geometry, seismicity, and deep structural fabric to constrain Community Fault (CFM) and Rheology (CRM) Models Vera Schulte-Pelkum, Deborah Kilb We combine newly available southern California data sets to provide constraints for refinement of the SCEC Community Fault Model (CFM) as well as development of the Community Rheology Model (CRM). We compare data from (1) the recently released CFM 5... more	21098
Talk 14-Sep (08:00)	Geology	Shallow Creep Along the Central San Andreas Fault from Differential Lidar Topography Chelsea Scott, Ramon Arrowsmith, Stephen DeLong, Michael Bunds, Nathan Toke, Manoochehr Shirzaei Topographic differencing reveals horizontal and vertical deformation of the Earth’s surface due to fault motion. This technique has been applied to large surface rupturing earthquakes where the along- and near-fault measurements show how the shallow... more	19123, 21107
Poster 137	FARM	Insights into Fault Friction and Caldera Collapse from the 2018 Kilauea eruption Paul Segall, Kyle Anderson The 2018 eruption of Kilauea volcano, Hawai`i, caused 62 repeatable collapse events in which the caldera dropped several meters, accompanied by Mw 4.7-5.4 Very Long Period (VLP) earthquakes. Collapses were exceptionally well recorded by GPS and... more
Poster 092	SAFS	The Black Belt Mylonite Zone and the Role of Tectonic Inheritance in Brittle Faulting in the San Gabriel Block Sarah Sengpiehl, Joshua Schwartz, Elena Miranda, Keith Klepeis, Gabriela Mora-Klepeis The Black Belt mylonite zone is a major mid-crustal ductile shear zone in the San Gabriel Mountains and its east-west strike parallels the strike of the Quaternary Cucamonga Thrust Fault. Here, we examine the role of pre-existing ductile tectonic... more	21140
Poster 185	Seismology	Tectonic and Seismicity Characteristics of Bengal Basin System (BBS) Daya Shanker, Mir Karim The Bengal basin system is located in the Northeast corner of the Indian shield and consists of three sub-basins. Different basins show different tectonic patterns. Tectonic patterns of the region have been changing in different geological ages,... more
Poster 093	SAFS	General seismic architecture of the Southern San Andreas fault zone around the Thousand Palms Oasis from a Large-N nodal array Pieter-Ewald Share, Hongrui Qiu, Benxin Chi, Frank Vernon, Yuri Fialko, Ellis Vavra, Amir Allam, Yehuda Ben-Zion We present results from a large-N seismic nodal deployment spanning the Banning and Mission Creek strands (BF and MCF) of the southern San Andreas fault (SSAF) near the Thousand Palms Oasis Preserve, California. Motivating this research are several... more
Poster 061	Geology	Mapping the fractures associated with the magnitude 6.4 Ridgecrest earthquake foreshock from July 4, 2019 Thomas Shea, Alba Rodriguez Padilla, Michael Oskin The 2019 Ridgecrest earthquake sequence generated a surface rupture, part of which was along a previously unknown fault perpendicular to the Little Lake Fault Zone. Using high-resolution airborne images collected by the National Center for Airborne... more
Poster 218	Seismology	Improved stress drop estimates for M 1.5 to 4 earthquakes in Southern California from 1996 to 2019 Peter Shearer, Rachel Abercrombie, Daniel Trugman We estimate stress drops for over 70,000 southern California earthquakes from 1996 to 2019 using a P-wave spectral decomposition approach. Based on our recent work documenting hard-to-resolve tradeoffs between absolute stress drop, stress-drop... more	21082
Poster 246	Seismology	Evaluating Source and Site Effects in Peak Ground Displacement Models for Earthquake Magnitude Calculation Jack Sheehan, Valerie Sahakian Peak ground displacement (PGD) ground-motion models (GMMs) derived from high-rate Global Navigation Satellite System (HR-GNSS) data are becoming more widely used in earthquake and tsunami early warning applications, both for magnitude and ground-... more
Poster 086	SAFS	Conjugate Rupture Patterns and Role of Fluids in the 2020 Maacama Fault, California Earthquake Swarm David Shelly, Robert Skoumal, Jeanne Hardebeck In August of 2020, an earthquake swarm initiated near the Maacama Fault and the town of Willits, California, with magnitudes up to Mw 4.2. Although generally decreasing in intensity, the swarm persisted episodically at least into December 2020. The... more
Poster 015	CXM	A 3-D crustal compositional model of S. California and its implications on the instantaneous stress state of the lithosphere Weisen Shen, Siyuan Sui, Alireza Bahadori, William Holt, Jeonghyeop Kim, Lajhon Campbell Constraining the stress and stressing rate of the California area with Geodynamic modeling requires knowledge of the seismic, thermal, and rheological properties of the lithosphere. In this presentation, we present a 3-D simulation of the dynamics... more	21177
Poster 100	Geodesy	Resolve 3-dimensional deformation field in southern California using GNSS and InSAR data Zheng-Kang Shen, Zhen Liu We have developed a 3D GNSS/InSAR integration algorithm and applied that to a compilation of GNSS and InSAR data in southern California. In the algorithm discrete GNSS data points are interpolated to obtain a 3D continuous velocity field, which is... more
Poster 213	Seismology	Long-base seismic interferometry reveals a hidden slow-slip event near the Anza seismic gap Yixiao Sheng, Aurélien Mordret, Korbinian Sager, Florent Brenguier, Pierre Boué, Baptiste Rousset, Frank Vernon, Yehuda Ben-Zion Aseismic slip, now recognized as a ubiquitous phenomenon, has been observed at all kinds of plate boundaries. Slow-slip events occurring along active faults can accommodate a large portion of the slip budget, and their occurrence has also been... more
Talk 12-Sep (17:00)	Geology	My Sojourn into and through Paleoseismology Kerry Sieh The advent of plate-tectonic theory gave a new basis for understanding earthquakes along the San Andreas fault – in the new paradigm, it was a transform fault between two great plates. This gave a secure start to quantitative seismic hazard. Allen... more
Poster 032	GM	The SCEC Broadband Platform: Open-Source Software for Strong Ground Motion Simulation and Validation Fabio Silva, Philip Maechling, Christine Goulet, Yehuda Ben-Zion The Southern California Earthquake Center (SCEC) Broadband Platform (BBP) is a collection of open-source scientific software modules that can simulate broadband (0-20+ Hz) ground motions for earthquakes at regional scales, compare simulation results... more	21115, 20019, 20114, 20163, 20205, 19055, 19055, 19130, 19150
Poster 122	SDOT	Pronounced Recharge and Discharge Phase Ground water in the Epicentral Region Caused Madoi (China) M 7.3 earthquake of 21 May 2021 Ramesh SINGH, Feng Jing, Anhua He On 21 May 2021 (UTC time), an earthquake (magnitude 7.3, epicenter 34.59°N, 98.34°E) occurred in Madoi County, Guoluo Prefecture, Qinghai Province of China along the Yellow River. Numerous large lakes and wetland areas are located in the epicentral... more
Poster 188	Seismology	Characterizing spatiotemporal stress orientations in regions with induced seismicity Rob Skoumal Induced seismicity predominantly occurs along pre-existing faults that are optimally oriented in the local stress field. The characterization of these spatially varying stresses is a crucial component of understanding and potentially quantifying the... more
Poster 247	Seismology	Testing Contour Triggering In ShakeAlert Earthquake Early Warning Deborah Smith, Jennifer Andrews, Jeff McGuire, Minh Huynh The ShakeAlert system for the West Coast of the United States traditionally uses the epicenter of earthquakes to determine whether an event is within the reporting boundary. This works well for most cases; however, there is the potential for large... more
Poster 120	SDOT	Time-dependent deformation of thermally-fractured granites observed in laboratory creep experiments. Hiroki Sone, Mayukh Talukdar, Katherine Condon Discrepancies between fault slip rates inferred from geological indicators and those inverted from geodetic velocities and kinematic block models have suggested that a significant fraction of relative plate motions are accommodated by off-fault... more	21135
Poster 159	FARM	Direct Measurements of Slow Slip Events on Novel Laboratory Fault Show Constant Stress Drop Will Steinhardt, Emily Brodsky Slow slip events are a critical part of the seismic cycle. An important debate about slow slip revolves around whether they have magnitude-independent stress drops as is observed for regular earthquakes. Generally, stress drops for slow slip events... more
Talk 15-Sep (15:00)	EEII	Spatial distributions of liquefaction for seismic risk analysis Jonathan Stewart Seismic risk for spatially distributed infrastructure is driven mainly by ground failure, defined as permanent ground displacements from mechanisms such as liquefaction, seismic compression, and landslides. Buried pipelines are relatively... more
Poster 020	CS	Improving web-based access tools for the SCEC Community Models Mei-Hui Su, Philip Maechling, Edric Pauk, Tran Huynh, Scott Marshall, Michael Floyd, Elizabeth Hearn, Laurent Montesi SCEC Community Models (CXM) are a set of community models that describe many features of southern California lithosphere and asthenosphere. Most of the models have domain datasets that are very large with some updated on a regular schedule. The... more
Poster 147	FARM	Propagation of Slow Slip Events on a Rough Fault Yudong Sun, Camilla Cattania Recent studies showed that slow slip events (SSEs) in subduction zones can happen at all temporal and spatial scales and propagate at a wide range of velocities. Heterogeneity of fault properties, such as fault roughness, is often invoked to explain... more
Poster 206	Seismology	Using Deep Learning-Enabled Seismology to Illuminate Structure and Stress during Injection-Induced Seismicity in Decatur, IL Vivian Tang, Sherilyn Williams-Stroud, Ahmed Elbanna Nearly 1.1 million tons of carbon dioxide (CO2) were injected into the Mt. Simon Sandstone, a deep saline reservoir in the Illinois Basin – Decatur from 11/2011 to 11/2014. Exploring the pressure and state-of-stress conditions is important for... more
Talk 17-Sep (08:00)	CXM	A Thermal Model of the Southern California: SoCal Likes It (Mostly) Hot Wayne Thatcher, David Chapman A lithospheric temperature model for Southern California is developed. Surface heat flow measurements at 237 sites are used to define 14 distinct heat flow regions where heat flow is relatively constant; the regions are chosen to conform to... more
Poster 158	FARM	A microphysical model of rate- and state-friction controlled by dislocation glide and backstress (internal stress) evolution Christopher Thom, Lars Hansen, David Goldsby, Emily Brodsky Despite its widespread use in earthquake nucleation and recurrence models, our understanding of rate- and state-friction is still largely empirical, limiting our confidence in extrapolating laboratory behavior to the seismogenic zone. While many... more
Talk 14-Sep (15:00)	Seismology	Constraining families of dynamic models using geological, geodetic and strong ground motion data Elisa Tinti, Emanuele Casarotti, Thomas Ulrich, Taufiq Taufiqurrahman, Duo Li, Alice-Agnes Gabriel The dense coverage and high quality of geodetic and seismic data allow us to image intriguing details of earthquake rupture kinematics, however the mechanical viability of such models is not guaranteed. Fully dynamic models are needed to provide a... more
Poster 026	CS	The Workflow of Large Scale Ground Motion Simulations: Preprocessing, forward simulations, postprocessing Christopher Tobar, Alexander Breuer When it comes to large scale ground motion simulation of earthquakes, there is a scientific gap in pipelining of a three step process: pre-processing, simulation, and post-processing. By pipelining this process, we are able to improve efficiency and... more
Poster 071	Geology	3D geometry and kinematics of the restraining bend at Signal Hill: implications for seismic hazard for the Newport-Inglewood fault, Los Angeles, CA Natasha Toghramadjian, John Shaw The Newport-Inglewood fault (NIF) is a complex strike-slip system that cuts over 50 kilometers through metropolitan Los Angeles, forming the southwestern edge of the Los Angeles basin. The fault poses one of the greatest deterministic seismic... more
Poster 214	Seismology	A tale of urban seismology: ambient seismic noise, machine learning methods, and seismic hazard analysis at the Seattle basin edge Natasha Toghramadjian, Laura Ermert, Marine Denolle Sedimentary basins amplify and prolong strong shaking during large earthquakes. The city of Seattle sits atop the Seattle basin, and faces high seismic hazard posed by both the regional-scale Cascadia subduction zone and crustal faults. The Seattle... more
Poster 075	Geology	Topographic expression of active faulting along the Great Valley Thrust system near Winters, northern California Charles Trexler, Alex Morelan, Stephen DeLong, Alexandra Pickering Seismic sources and their associated hazards within the Sacramento-San Joaquin Delta region of north-central California (‘Delta’) are relatively poorly characterized, in part because faults have slow slip rates, likely < 5 mm/yr. These faults... more
Poster 181	Seismology	Initial Tests of a Bayesian Framework for Directivity and Source Spectral Analysis: Application to the July 2019 Ridgecrest Earthquake Sequence Daniel Trugman Earthquake source spectra can provide crucial observational constraints for understanding the physics of earthquake rupture. While there exist a number of approaches to extract key earthquake source parameters like corner frequency and stress drop... more	21017
Poster 170	FARM	Structural Controls Over the 2019 Ridgecrest Earthquake Sequence Investigated by High-Fidelity Elastic Models of 3D Velocity Structures Sui Tung, Manoochehr Shirzaei, Chandrakanta Ojha, Antonio Pepe, Zhen Liu We develop finite element models of the coseismic displacement field accounting for the 3D elastic structures surrounding the epicentral area of the 2019 Ridgecrest earthquake sequence containing two major events of Mw7.1 and Mw6.4. The coseismic... more	19131

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