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 151-200 of 292

SCEC ID	Category	Title and Authors	SCEC Award
Poster 227	Seismology	Earthquake Phase Association with Graph Neural Networks Ian McBrearty, Gregory Beroza In this work we present a new Graph Neural Network (GNN) architecture for earthquake phase association, in which we process streaming pick datasets, determine the number and location of earthquakes in a time window, and associate picks to each... more
Poster 178	FARM	Creep fronts and asperity interactions in laboratory earthquake sequences illuminate delayed earthquake triggering Gregory McLaskey, Sara Cebry, Chun-Yu Ke, Srisharan Shreedharan, Chris Marone, David Kammer Earthquakes occur in clusters or sequences that imply heterogeneous fault properties and complex triggering mechanisms. We have developed a laboratory experiment and supporting numerical simulations that illustrate delayed triggering and repeating... more
Poster 079	Geology	Preliminary paleoseismic observations of the Ione Valley Fault, Basin and Range Province, central Nevada James McNeil, Rich Koehler The Ione Valley fault is a north-northeast striking, range-bounding, dip-slip fault that bounds the western margin of the Shoshone Range in west-central Nevada. The fault sits directly east of the Mina deflection, a major right step in the NW... more
Poster 047	GM	Testing the seismic response of rock pillars using in situ strength measurements Devin McPhillips, Joaquin Garcia Suarez, Emiliano Gonzalez, Katherine Scharer, Domniki Asimaki Rock pillars are a type of fragile geologic feature (FGF) that may constrain the intensity of past earthquake shaking. Unlike some other FGFs, such as precariously balanced rocks, rock pillars are materially connected to bedrock at their bases. In... more	20068, 20119
Poster 144	FARM	Laboratory investigation of multiple controls on fault stability and rupture dynamics Cheng Mei, Sylvain Barbot, Wei Wu The stability of frictional sliding affects the spectrum of fault slip, from slow-slip events to earthquakes. In laboratory experiments, the transition from stable sliding to stick-slip is often explained by the ratio of the stiffness of the loading... more
Poster 191	Seismology	Finite-source attributes of 39 M 3.9 to 5.5 Ridgecrest, California earthquakes Haoran Meng, Wenyuan Fan, Jeff McGuire, Elizabeth Cochran We apply a time-domain approach that makes minimal assumptions to estimate the second-degree seismic moments of 39 M 3.9 to 5.5 earthquakes of the 2019 Ridgecrest, California sequence. Resolving earthquake rupture processes is essential both for... more	20115
Poster 130	FARM	Explore the mechanism of tsunami earthquake generation using earthquake cycle simulation Qingjun Meng, Benchun Duan, Bin Luo Since 1900, nine Mw>=7.5 historical tsunami earthquakes have occurred along shallow subduction zones and generated larger tsunami hazards than their Ms magnitudes implied. Previous observations found that tsunami earthquakes propagate at slower... more
Poster 036	GM	A Nonergodic Ground Motion Model in Southern California with Spatially Varying Coefficients Using a SCEC CyberShake Dataset Xiaofeng Meng, Christine Goulet, Kevin Milner, Scott Callaghan A key input to probabilistic seismic hazard analyses (PSHA) is the total standard deviation of the misfits between ground motion observations and the median ground motion models (GMMs, a.k.a GMPEs). The most promising way to reduce hazard is to... more	21122
Poster 003	CEO	Engaging students using virtual reality for earthquake science: first-impressions from in-person and remote collaboration Michael Methvin, Dianne Pham, Christodoulos Kyriakopoulos, Ashley Webb Finding innovative ways to communicate earthquake related topics is fundamentally important to spreading awareness about earthquake hazard. Virtual Reality (VR) provides unique outreach and educational opportunities and allows students to interact... more
Poster 149	FARM	Role of injection location and injection pressure magnitude in modulating sequence of induced earthquakes and aseismic slip Md Shumon Mia, Mohamed Abdelmeguid, Ahmed Elbanna Mitigation of induced seismicity hazard continues to be a major challenge in several geo-energy applications including fossil fuel extraction, carbon sequestration and waste-water injection. A key to address this challenge is developing tools for... more
Poster 136	FARM	Origins of roughness evolution and strategies for its implementation on rate-state faults Enrico Milanese, Tobias Brink, Ramin Aghababaei, Jean-François Molinari, Camilla Cattania Friction and wear are physical phenomena that emerge upon sliding of one surface against another. They are thus found in a wide variety of setups and at all scales -- from geological faults to nanoscale engineering applications. A key role in the... more
Poster 109	SDOT	Resolving Coseismic Stresses Using 3D Geodetic Imaging Data: Examples from the 2019 Ridgecrest Earthquake Sequence Chris Milliner, Saif Aati, Jean-Philippe Avouac Constraining the variation of stress throughout the crust along fault zones and over time has importance for improving our understanding of the mechanics of faulting and estimating the hazard of distributed fault rupture and seismic ground motions.... more
Talk 15-Sep (11:00)	Geodesy	Characterizing the Deformation and Hazard of Fault Zones Using Geodetic Imaging Data Chris Milliner, Jean-Philippe Avouac, Saif Aati, Rui Chen, Brian Chiou, Timothy Dawson, Andrea Donnellan, James Dolan Understanding how inelastic, co-seismic shear strain attenuates with distance away from the primary fault rupture is important for accurately characterizing the hazard it poses to critical infrastructure and estimating the full geologic slip rate.... more	19222
Poster 029	CS	OpenSHA: New tools and file formats for building and analyzing UCERF3-style rupture sets and running inversions Kevin Milner, Edward Field The 3rd Uniform California Earthquake Rupture Forecast (UCERF3) model, released in 2014, introduced Fault System Rupture Sets and Solutions as data containers for fault-based earthquake rupture forecasts. A Rupture Set defines all of the on-fault... more	21148
Poster 254	EFP	Towards next-generation earthquake forecasting by embracing short-term aftershock incompleteness Leila Mizrahi, Shyam Nandan, Stefan Wiemer Epidemic-Type Aftershock Sequence (ETAS) models are the most successful earthquake forecasting models currently available, both for short- and long-term hazard assessment. They account for the spatio-temporal clustering of earthquakes intrinsically... more
Poster 018	CXM	Predicted Ductile Rheology of Textured and Non-Textured Rocks in Southern California Laurent Montesi, Greg Hirth, Michael Oskin Rheology controls how global and local stress sources are redistributed through the lithosphere to produce the observed deformation field and to load potentially seismogenic faults. Even though most geodynamical models assume uniform rheology,... more	20084
Poster 014	CXM	Parsimonious velocity inversion applied to the Los Angeles Basin, CA Jack Muir, Robert Clayton, Victor Tsai, Quentin BRISSAUD Effectively combining local high-resolution tomographic results with existing regional models presents an ongoing challenge. We have recently developed a framework based on the Tikhonov-regularized level-set method that provides a simple means to... more	20024
Poster 250	EFP	A more realistic model for the probability of large earthquakes James Neely, Leah Salditch, Bruce Spencer, Seth Stein Earthquake hazard mitigation requires accurate earthquake probability models. However, current models ignore complexities of the strain accumulation and release processes that drive earthquakes. They assume that a large earthquake releases all... more
Poster 231	Seismology	Comparison of Stress Drop Variation of M3.8-4.2 Earthquakes Between 0-12 km Depth Using Four Independent Methods on 2019 Ridgecrest, CA Data Arjun Neupane, Christine Ruhl, Rachel Abercrombie Earthquake static stress drop is an enigmatic and highly uncertain source parameter to measure, but is fundamentally related to the rupture process and is needed to understand observed variations in strong ground motion between different events. Too... more	21083
Poster 007	CXM	Updates and Additions to the Community Fault Model (CFM version 5.3): detachments, cross faults and en echelon fault sets Craig Nicholson, Andreas Plesch, John Shaw, Egill Hauksson Since its introduction in 2001, the Community Fault Model (CFM) has continued to progress, expand and improve, culminating in the recent release of CFM version 5.3 (Nicholson et al., 2020; Plesch et al., 2020; Marshall et al., 2021). This on-going... more	21023
Poster 150	FARM	Pulse-like ruptures linked to chaotic recurrence patterns in seismic cycles with compliant fault zones Shiying Nie, Sylvain Barbot Seismic cycles materialize in various rupture styles, from slow-slip events, to slow and fast earthquakes. Meanwhile, the paleoseismic record documents various recurrence patterns for large earthquakes, going from periodic to much more complex... more
Poster 253	EFP	Modified estimation and forecasting of the hierarchical space-time ETAS (HIST-ETAS) model for earthquake catalogs in a wide area possessing long- and short-term incompleteness Yosihiko Ogata, Koichi Katsura In this study, we use the hierarchical spatio-temporal ETAS (HIST-ETAS) model to make short-term forecasts of region-dependent seismic activity and to separate background seismicity rates over a wide area, such as all of Japan and inland areas. In... more
Poster 177	FARM	The effects of Absolute Friction Level on Shallow Fault Dynamics David Oglesby, Baoning Wu, Christodoulos Kyriakopoulos, Kenny Ryan Earthquakes that rupture up to the Earth’s surface pose significant threats to populations. However, our quantitative understanding on how the free surface affects earthquake rupture is still incomplete. At present, modelers still heavily rely on... more	21153
Poster 042	GM	0-5 Hz Deterministic 3D Ground Motion Simulations for the 2014 La Habra, California, Earthquake Kim Olsen, Zhifeng Hu, Steven Day We have simulated 0-5 Hz deterministic ground motions for the 2014 Mw 5.1 La Habra, CA, earthquake in a mesh from the SCEC Community Velocity Model Version S4.26-M01 with a finite-fault source. Our simulations include statistical distributions of... more	19221
Poster 182	Seismology	Searching for Hidden Microearthquakes using Data-based, Physics-based, and Hybrid Models: Implications for Salt Dome Monitoring Joses Omojola, Patricia Persaud, Rufus Catchings, Mark Goldman Earthquakes in stable salt domes are few, with a notable increase in the rate of seismicity prior to catastrophic events, such as the collapse of salt caverns used to store hydrocarbons. Cavern collapse, subsequent gas leakage, and the formation of... more
Poster 083	Geology	Changes in rock uplift rates and fault slip rates over the past 125 ky in the western Transverse Ranges Nate Onderdonk, Clay Kelty, Ian McGregor, Eric Tutterow A sequence of Quaternary fluvial and marine terraces in the Western Transverse Ranges (WTR) of California record the pattern and rates of rock uplift, folding, and faulting over the past 125 ky and show that deformation is not steady through time... more
Poster 135	FARM	Numerical modelling of rupture dynamics constrained by past seismicity for ground motion prediction Elif Oral, Jean-Paul Ampuero, Javier Ruiz, Domniki Asimaki Predicting ground motion by physics-based modelling, particularly at magnitudes and distances that lack empirical data, has been an attractive avenue for seismic hazard assessment studies. In the proximity of a fault, both source- and site-related... more	21010
Poster 256	EFP	Aftershocks Preferentially Occur in Previously Active Areas Morgan Page, Nicholas van der Elst The clearest statistical signal in aftershock locations is that most aftershocks occur close to their mainshocks. To first order, aftershocks are triggered at distances following a power-law decay in distance (Felzer and Brodsky, 2006). While... more
Poster 187	Seismology	Change in seismic velocity during laboratory triaxial stick-slip experiments Kiran Pandey, Thomas Goebel, Taka'aki Taira, Georg Dresen Seismic velocity changes resulting from crack opening and closure within fault damage zones may be indicative of stress state and proximity to failure. However, such velocity changes are commonly extremely small and thus hard to resolve in the... more
Poster 257	EFP	An Interactive Web Tool to Visualize and Improve USGS Operational Aftershock Forecasts Gabrielle Paris, Andrew Michael The USGS Earthquake Hazards Program provides information to the public when potentially damaging earthquakes happen. The Operational Aftershock Forecasting (OAF) system (https://earthquake.usgs.gov/data/oaf/) publishes the chance of more earthquakes... more
Poster 043	GM	The Effect of Earthquake Depth on Ground Motion Predictions for Earthquake Early Warning Alerting Grace Parker, Annemarie Baltay We investigate the influence of earthquake source depth on subduction zone ground motion model (GMM) predictions in the context of the U.S. Geological Survey (USGS) ShakeAlert Earthquake Early Warning System. ShakeAlert forecasts alert regions using... more
Poster 241	Seismology	Linking sediment strength and earthquake shaking to understand the Cascadia Subduction Zone paleoseismic record Kiki Paroissien-Arce, Tara Nye, Valerie Sahakian Records of turbidites offshore Cascadia are an integral part of detangling the Cascadia Subduction Zone paleoseismic record, and support estimates of seismic hazard. In this study, we aim to extend this work, and re-examine some current assumptions... more
Poster 183	Seismology	Quantifying the Sensitivity of Microearthquake Slip Inversions to Station Distribution Using the LASSO Nodal Array in Oklahoma Colin Pennington, Hilary Chang, Justin Rubinstein, Rachel Abercrombie, Nori Nakata, Takahiko Uchide, Elizabeth Cochran To investigate the sensitivity of slip inversions to station distribution we examine three microearthquakes (M1.7, M2.1, and M2.7) that occurred within the high density LArge-n Seismic Survey in Oklahoma (LASSO) nodal array. The LASSO array’s dense... more
Talk 17-Sep (08:00)	CXM	Borehole-Derived Stress Constraints for High-Risk Fault Systems in Southern California Patricia Persaud, Joann Stock Several previous studies have used different stress indicators to provide constraints on crustal stress in Southern California. They noted that regional and local stress variations exist at various spatial scales and degrees of heterogeneity, and... more	20022
Poster 060	Geology	Trenching the causative faults of the 2019 Ridgecrest sequence Ian Pierce, Alana Williams, Rich Koehler, Ramon Arrowsmith The 2019 Ridgecrest earthquake sequence consisted of a M6.4 rupture along the Salt Wells Valley left-lateral strike-slip fault on July 4th, 2019, followed by a M7.1 rupture of the nearly perpendicular Paxton Ranch right-lateral strike-slip fault on... more	20103
Poster 005	CXM	Updates to the SCEC Community Fault Model (CFM), and to web-based tools, and plans for its peer review and version 6.0 Andreas Plesch, Scott Marshall, Ana Luiza Nicolae, John Shaw, Philip Maechling, Mei-Hui Su We present a series of enhancements to the Community Fault Model (CFM) and the web-based tools that help to support its use in a wide range of SCEC activities. The CFM is one of the most established SCEC community models, and is now accessed through... more	21018, 21009, 21080
Talk 17-Sep (08:00)	CXM	The SCEC CVM effort: new basin models, enhanced access and tomographic updates Andreas Plesch, Clifford Thurber, Carl Tape, John Shaw The SCEC Community Velocity Model (CVM) offers 3D descriptions of seismic wave speeds in Southern California's crust and upper mantle. One is based on a sedimentary basin description from stratigraphic layering rules (CVM-S) which is heavily... more	20040, 19017, 20071, 21080
Poster 069	Geology	Localized and distributed deformation in a step-over of the Ridgecrest 2019 mainshock Ruth Prado, Alba Rodriguez Padilla, Michael Oskin High-resolution aerial images of the surface provide an opportunity to map surficial deformation from earthquakes in detail. We mapped the northern step-over region of the Ridgecrest 2019 Mw 7.1 mainshock from 5cm per pixel aerial imagery collected... more
Talk 14-Sep (08:00)	Geology	Revisiting geologic fault slip rates - and their uncertainty - across southern California Veronica Prush, Michael Oskin Models of earthquake hazard rely on geologic fault slip rates to forecast future activity. With the increasing complexity of earthquake forecasting, it's crucial to apply consistent uncertainty models to the input geologic data. To date, the... more	17121, 15209
Poster 025	CS	Forward-Inverse Modeling of Earthquake Cycle Deformation Simone Puel, Thorsten Becker, Umberto Villa, Omar Ghattas, Dunyu Liu, Eldar Khattatov Analysis of coseismic and postseismic surface displacements can help to constrain the Earth's structure and physics of deformation mechanisms occurring at depth. Here, we propose a new finite-element (FE) based computational framework to solve... more
Poster 211	Seismology	NEAR-SURFACE SHEAR WAVE VELOCITY AND ATTENUATION AT GARNER VALLEY, CALIFORNIA Lei Qin, Jamison Steidl, Kenneth Hudson, Timothy Lamere, Hongrui Qiu, Yehuda Ben-Zion We analyze data from seismic and pore pressure stations at 0-50 m depths, and a cross-hole array experiment, from the Garner Valley Downhole Array, to estimate shear-wave velocities and attenuation in the near-surface structure. Impulse response... more
Poster 208	Seismology	Internal structure of the Garlock fault zone from Ridgecrest aftershocks data recorded by dense linear arrays Hongrui Qiu, Benxin Chi, Yehuda Ben-Zion The left-lateral strike-slip Garlock Fault runs northeast–southwest along the southern ends of Sierra Nevada and north margins of the Mojave Desert of Southern California. Although no significant ruptures have occurred in the past century, the... more
Poster 064	Geology	Near-field deformation of the southeastern strand of the 2019 Ridgecrest mainshock Mercedes Quintana, Alba Rodriguez Padilla, Duncan Chadly, Michael Oskin The Ridgecrest earthquake sequence occurred in July 2019 in the Eastern California Shear Zone, generating a complex surface rupture. Some sections of the surface rupture were captured with 2-20cm per pixel drone imagery collected by Pierce et al. (... more
Poster 217	Seismology	Seismotectonics of the California-Baja California region. Erik Ramírez-Ramos, Joann Stock, Zachary Ross, Antonio Vidal-Villegas, Jorge Ramírez Hernández Mapped and unknown faults in the northern Baja California region have generated earthquakes of high magnitudes, which have caused significant damages to the infrastructure, water canals, croplands, etc. For this study, we build a new seismic catalog... more
Poster 054	EEII	Predicting Damage to Steel Rebar in Reinforced Concrete Structures Subjected to Earthquake Loading Leslie Ramos, Maha Kenawy High-intensity ground shaking can cause significant damage to civil structures and interruption of community functions. Structural components, such as reinforced concrete (RC) columns, deteriorate and accumulate damage during high-intensity shaking... more
Poster 045	GM	Joint Calibration of NGA-East GMMs and Site Amplification Models Against CENA Ground Motions Maria Ramos-Sepulveda, Grace Parker, Meibai Li, Okan Ilhan, Halil Uysal, Youssef Hashash, Ellen Rathje, Jonathan Stewart Ground motion models (GMMs) are used by the engineering community to estimate ground motion intensity measures given the source earthquake and wave propagation path. The Next Generation Attenuation (NGA) projects have developed GMMs for the main... more
Talk 15-Sep (15:00)	EEII	Regional Assessments of Earthquake-Induced Landslides Ellen Rathje, Olaide Ojomo, Krishna Kumar Earthquake-induced landslides represent a significant seismic hazard, with some earthquake events generating thousands of landslides that affect massive areas. The considerable number and size of landslides induced by earthquakes has the potential... more
Poster 172	FARM	Aseismic slip on rate-weakening interfaces Sohom Ray, Dmitry Garagash We highlight how slow aseismic slip travels long distances on rate-weakening interfaces. We considered two model faults with sliding rate- and state-dependent interfacial shear strength: a thin deformable layer over a substrate and a slip surface... more
Poster 164	FARM	Dynamic fault weakening during earthquakes: Rupture or Friction? Ze'ev Reches, Xiaofeng Chen, Sai-Sandeep Chitta, Ximeng Zu An earthquake is an event of dynamic, unstable slip that releases elastic energy stored in the earth’s crust. This abrupt energy release requires the weakening of the slipping fault that is manifested by a strength drop from a static level to a... more
Poster 073	Geology	Late Holocene Rupture History of the Ash Hill Fault, Eastern California Shear Zone Christine Regalla, Eric Kirby, Shannon Mahan, Eric McDonald Several recent, large-magnitude earthquakes in the Eastern California Shear Zone (ECSZ) help serve as a reminder of the role that intraplate faults play in accommodating plate boundary deformation. Understanding how seismogenic strain is distributed... more	18048

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