Meeting Abstracts

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 form below to search and view all poster and invited talk abstracts submitted to this meeting.

Results 1-50 of 320

SCEC ID	Category	Title and Authors	SCEC Award
Poster 272	Ridgecrest	ShakeAlert Earthquake Early Warning Performance for the 2019 Ridgecrest Sequence Brad Aagaard, Sarah Minson, Annemarie Baltay, Elizabeth Cochran, Tom Hanks We evaluate the performance of the ShakeAlert earthquake early warning (EEW) system for M5+ earthquakes in the 2019 Ridgecrest earthquake sequence using a cost-savings, ground-motion-based performance metric for public alerting strategies. We find... more
Poster 232	Ridgecrest	Surface deformation of the Mw 6.4 and Mw 7.1 Ridgecrest earthquakes measured from subpixel correlation of Copernicus Sentinel-2 optical images Saif Aati, Jean-Philippe Avouac We use sub-pixel correlation of optical images to measure surface deformation in the epicentral area of the Mw6.4 Searles Valley and the Mw 7.1 Ridgecrest earthquakes, which struck California on July 4, and 5 respectively. This study provides an... more
Poster 167	FARM	Modeling sequence of earthquakes and aseismic slip (SEAS) in low-velocity faults zones using a computationally efficient numerical algorithm Mohamed Abdelmeguid, Xiao Ma, Ahmed Elbanna Modeling earthquake ruptures is a complex challenge due to the eclectic sources of nonlinearities and heterogeneities, such as friction, plasticity, nonplanar fault surfaces, and material damage. In addition to the nonlinearities, another... more
Poster 182	FARM	Just how similar are individual earthquakes within repeating sequences at Parkfield? Rachel Abercrombie, Xiaowei Chen, Jiewen Zhang The discovery of repeating sequences of earthquakes on the San Andreas at Parkfield has led to significant advances in our understanding of fault mechanics, and earthquake rupture dynamics. But just how similar are the repeating events? How similar... more
Poster 192	SDOT	Numerical simulations of stress variations with depth in a model for the San Jacinto fault zone Niloufar Abolfathian, Christopher Johnson, Yehuda Ben-Zion Depth dependent crustal stress orientations in strike-slip faulting environments are explored using quasi-static numerical simulations with variations of fault geometry and rheology of a layered substrate, to compare model predictions with stress... more	19136
Poster 216	Geodesy	Mitigation of atmosphere noise in satellite interferometry through machine learning DongChan Ahn, Zhen Liu Interferometric synthetic aperture radar (InSAR) is a radar imaging technique widely used to track surface deformation. InSAR can measure surface deformation with centimeter to millimeter accuracy, but is susceptible to noise. One major noise source... more	17225
Poster 055	Seismology	Evaluating seismic velocity models in the Salton Trough, Southern California using spectral-element wave simulation of validation events Rasheed Ajala, Patricia Persaud, Alan Juarez, Gboyega Ayeni The Southern California ShakeOut Scenario considers a potential M7.8 earthquake that initiates on the southernmost section of the San Andreas fault in the Salton Trough, with energy propagating northward into the Los Angeles basin. To improve... more	19014, 18074
Poster 255	Ridgecrest	A Multiscale Seismic Deployment with 463 Sensors Following the 2019 Ridgecrest Earthquake Sequence in Eastern CA Amir Allam, Rufus Catchings, Jamison Steidl, Elizabeth Berg, Nathan Downey, Yehuda Ben-Zion, Mark Goldman, Joanne Chan, Coyn Criley, Daniel Langermann, Adrian McEvilly, Ziqiang Ma, Daniel Mongovin The 2019 Ridgecrest Earthquake sequence in the Eastern California Shear Zone includes the M6.4 and M7.1 July 4-5 events and numerous aftershocks that extend to the north towards the Owens Valley and to the south towards the Garlock fault. The July... more
Poster 282	FARM	Shear localization from the interplay between fault motion and grain size evolution Kali Allison The formation of ductile shear zones in the lower crust and upper mantle and their interaction with brittle faults remains an open question in continental tectonics. We explore how grain size evolution, shear zone structure, and fault motion are... more
Poster 189	FARM	Fault Damage Zones in 3D with Active-Source Seismic Data Travis Alongi, Emily Brodsky, Jared Kluesner, Daniel Brothers Damage zones are important to the rupture dynamics, evolution and fluid coupling of earthquakes. However, information about the damage zone at depth is limited. It is unclear if damage zones increase or decrease in intensity with depth. Here we use... more	19213
Poster 155	FARM	Revisiting the classical earthquake experiment in the Rangely oil Field, Colorado, 1970: insights from coupled flow and geomechanical modeling Josimar Alves da Silva, Hannah Byrne, Andreas Plesch, John Shaw, Ruben Juanes The earthquake experiment conducted in the Rangely oil field, Colorado, in 1970, was pioneering in elucidating the correlation between wastewater injection and induced earthquakes. This correlation, in spite of the wealth of data collected during... more
Poster 261	Ridgecrest	Seismic Velocity Changes Associated with the 2019 Ridgecrest Earthquake Sequence Yanru An, Taka'aki Taira, Chenyu Li, Zhigang Peng The 2019 M 7.1 Ridgecrest earthquake sequence triggered widespread local and regional seismicity including the Coso Geothermal Field (CGF). To understand spatiotemporal variations in stress transients associated with the Ridgecrest sequence, we... more
Poster 002	GM	Empirical Self-similar Double-corner Frequency Spectrum as a Model for the Earthquake Source Ralph Archuleta, Chen Ji We introduce a self-similar double-corner-frequency (DCF) source spectrum. Its displacement spectrum amplitude remains constant for frequency less than f_c1, decays as f^(-1) between f_c1 and f_c2, and f^(-2) for frequency larger than f_c2. The two... more	17247
Poster 208	Geodesy	Quantitative relationship between aseismic slip propagation speed and frictional properties Keisuke Ariyoshi, Jean-Paul Ampuero, Roland Bürgmann, Takanori Matsuzawa, Akira Hasegawa, Ryota Hino, Takane Hori Recent observations show evidence of propagation of postseismic slip, which may contain information about the mechanical properties of faults. Here, we develop a new analytical relationship between the propagation speed of aseismic slip transients... more
Poster 157	FARM	Detecting asperity flash heating on hematite faults from deformation experiments and (U-Th)/He thermochronometry Alexis Ault, Gabriele Calzolari, Greg Hirth, Robert McDermott Co-seismic temperature rise, which induces dynamic weakening, is challenging to directly document in natural and experimental fault rocks. Hematite (U-Th)/He (He) thermochronometry is sensitive to transient high temperature events. Thus, hematite-... more	17164
Poster 025	EFP	The Predictable Chaos of Slow Earthquakes Jean-Philippe Avouac, Adriano Gualandi, Sylvain Michel, Davide Faranda Slow Slip Events (SSEs) are episodic slip events that play a significant role in the moment budget along subduction megathrust. They share many similarities with regular earthquakes, and have been observed in major subduction regions like, for... more
Poster 160	FARM	Thermal pressurization in experimental faults Nir Badt, Terry Tullis, Greg Hirth Thermal pressurization (TP) is expected to be a dominant process during earthquake rupture, however most of our understanding on TP relies on theoretical studies. Our unique experimental setup allows us to test the mechanical response of... more	19117
Poster 029	EFP	The USGS Automatic Aftershock Forecasting System Michael Barall, Andrew Michael, Jeanne Hardebeck Last year, the USGS expanded aftershock forecasts to the nation with upgraded methods and presentation on the USGS website. A forecast is probabilistic and includes information such as the probability that an M6 aftershock will occur in the next... more
Poster 163	FARM	Controlling the life-time and rest-time of asperity contact populations to investigate the temperature and stress distribution in flash-weakened frictional surfaces in granite Monica Barbery, Frederick Chester, Judith Chester For frictional sliding in rock at rates >0.01 m/s, the coefficient of friction (µ) can be reduced by flash heating at asperity contacts and by the associated rise in average temperature of the sliding surface. Using a high-velocity (~1 m/s), high... more	17253
Poster 253	Ridgecrest	Earthquake Magnitudes from Dynamic Strain: Application to the 2019 Ridgecrest Earthquakes Andrew Barbour, Noha Farghal We investigate the attenuation and geometrical spreading characteristics of dynamic strain measurements of seismic waves from local earthquakes. We assemble a catalog of earthquakes along the Pacific/North-American plate boundary with moment... more
Poster 024	GM	Region-Specific Fourier-Based Site Amplification Modeling Jeff Bayless, Andreas Skarlatoudis, Jonathan Stewart There is increasing recognition that simulations can be utilized in engineering applications, but for the simulations to be accepted, they need to be validated first. To facilitate future validations, we develop a Fourier-based site amplification... more	19097
Poster 036	EFP	A regionalized seismicity model for subduction zones based on geodetic strain rates, geomechanical parameters and earthquake-catalog data José Bayona Viveros, Sebastian von Specht, Anne Strader, Sebastian Hainzl, Fabrice Cotton, Danijel Schorlemmer The Seismic Hazard Inferred from Tectonics based on the Global Strain Rate Map (SHIFT_GSRM) earthquake forecast was designed to provide high-resolution estimates of global seismicity to be used for seismic hazard assessment. This model combines... more
Poster 125	Geology	The 1983 Borah Peak earthquake (M7.3) (Idaho - USA) - 3D architecture and seismotectonics along the Lost River fault from field observations and high-resolution topography integrated with seismological data Simone Bello, Ramon Arrowsmith, Chelsea Scott, Giusy Lavecchia, Tyler Scott, Rita De Nardis, Federica Ferrarini The Lost River Fault (LRF; northern Basin and Range, USA) is composed of six segments and of a large number of multi-scale en-echelon SW- to SSW dipping normal and normal oblique fault surfaces. Two NNW-SSE trending segments, known as Warm Spring (... more
Poster 131	SAFS	Barriers to rupture propagation may be different beneath the surface: Insights from the Elizabeth Lake paleoseismic record Sean Bemis, Katherine Scharer, James Dolan Structural complexity and stress release history along active faults systems may exert significant controls on the locus and extent of individual earthquake ruptures. Fault bends are often invoked as a possible mechanism for terminating earthquake... more	14202, 13136, 12157
Poster 068	Seismology	Pre-earthquake Response: Closing critical data gaps and preparing for large earthquakes Yehuda Ben-Zion, Mark Benthien, Jason Ballmann, Christine Goulet The limited understanding of earthquakes stems partially from their highly complex dynamics, along with significant observational gaps in the available in-situ data. The existing natural observations in earthquake physics are generally associated... more
Poster 289	GM	Ground Motion Prediction Constraints and Hazard Curve Evaluation in Southern California Using Precariously Balanced Rocks Glenn Biasi, John Anderson, James Brune, Richard Brune Precariously balanced rocks (PBRs) provide approximate bounds on unexceeded ground motions for the period of their current configuration. For many PBRs, this can be thousands of years, which is much longer than any instrumental records. We use... more	15038
Poster 241	Ridgecrest	Triggered slip and afterslip in the 2019 Ridgecrest earthquakes: evidence for rotation of fault zone fabrics Roger Bilham, Castillo Bryan We report sub-cm triggered slip and afterslip from eighteen creepmeters in the epicentral region and at distances of up to 450 km from the Ridgecrest earthquake sequence. Eleven extensometers 300-450 km south and NE of the July 2019 Mw6.4 and Mw7.1... more
Poster 135	SAFS	Evidence for an alternative position for the primary active strand of the San Andreas Fault along its restraining bend in southern California Kimberly Blisniuk, Greg Balco, Julie Fosdick, Jesse Waco This study summarizes new multi-proxy data to provide evidence for an alternative position for the primary active strand of the southern San Andreas Fault along its restraining bend. We combine data from LiDAR imagery, field mapping, sedimentary... more
Poster 179	FARM	Detailed space-time variations of shallow seismic velocities at the San Jacinto fault zone based on autocorrelation analysis of dense array data Luis Bonilla, Yehuda Ben-Zion The Sage Brush Flat (SGB) site in the trifurcation area of the San Jacinto fault zone (SJFZ) southeast of Anza, California, had a dense array of 1,108 vertical ZLand nodes recording continuous waveforms for ~30 days in spring of 2014. The dense... more	19072
Poster 116	Geology	Termination of the Palos Verdes Fault at Lasuen Knoll: Evaluating Models of Geometry, Kinematics and Potential Connectivity Daniel Boyd, Jayne Bormann The Palos Verdes fault (PVF) is an active component of the Inner California Borderlands offshore strike-slip fault system that collectively accommodates ~6-8 mm/yr of Pacific-North American plate boundary shear. The PVF extends 95 km from Santa... more
Poster 100	Geology	Dating the duration of deformation along a major shear zone within the Eastern Peninsular Ranges Batholith Adam Brackman, Jeremy Torres, Joshua Schwartz, Elena Miranda, Sinan Akciz Understanding the formation and evolution of continental crust in Southern California is a complex inverse problem due to the ever-evolving tectonics of the region. Determining an accurate date for the formation of the unaltered protolith of the... more
Poster 019	GM	Cybershake NZ v19.5: New Zealand simulation-based probabilistic seismic hazard analysis Brendon Bradley, Jonney Huang, Jason Motha, Karim Tarbali, Robin Lee, Sung Bae, V Polak, M Zhu, C Schill, J Patterson, D Lagrava This poster presents the computational components and results of the May 2019 version (v19.5) of probabilistic seismic hazard analysis (PSHA) in New Zealand based on physics-based ground motion simulations (‘Cybershake NZ’). A total of 11,362 finite... more
Poster 186	FARM	Slip partitioning and plate kinematic barriers to megathrust rupture Kyle Bradley, Wardah Shafiqah Binti Mohammad Fadil , Shengji Wei Great earthquakes arise from horizontal propagation of fault ruptures over distances approaching the length of Earth’s minor tectonic plates. At these scales, the rotational relative motion of rigid plates dictates the rate and direction in which... more
Poster 050	Seismology	Train traffic as a powerful noise source for monitoring active faults with seismic interferometry Florent Brenguier, Pierre Boué, Yehuda Ben-Zion, Frank Vernon, Christopher Johnson, Aurelien Mordret, O Coutant, Pieter-Ewald Share, E Beaucé, Daniel Hollis, T Lecocq Laboratory experiments report that detectable seismic velocity changes should occur in the vicinity of fault zones prior to earthquakes. However, operating permanent active seismic sources to monitor natural faults at seismogenic depth is found to... more
Poster 043	Seismology	Improving the resolution of co-seismic velocity change monitoring at active fault zones using the ambient seismic field Jared Bryan, Kurama Okubo, Congcong Yuan, Marine Denolle The release of accumulated strain energy during dynamic earthquake ruptures causes stress relaxation around the fault. Off-fault fractures are co-seismically generated around the rupture front due to high stress concentrations, and this damage can... more
Poster 104	Geology	Dating of Offset Geomorphic Features Along the Garlock Fault, Mojave Desert, California: Testing a Proposed Earthquake Supercycle Model James Burns, Sally McGill, Ed Rhodes, James Dolan, Nathan Brown Recent investigations of the Garlock Fault at the northern edge of the Mojave Desert point to a strongly irregular pattern of earthquake recurrence, which may be related to temporal variations in slip rate on the fault. These previously published... more
Poster 297	CS	New Advances in CyberShake PSHA Models Scott Callaghan, Philip Maechling, Christine Goulet, Kevin Milner, Mei-Hui Su, Robert Graves, Kim Olsen, Yifeng Cui, Brad Aagaard, Kathryn Wooddell, Albert Kottke, Bruce Shaw, Thomas Jordan SCEC has developed the CyberShake software platform to perform 3D physics-based probabilistic seismic hazard analysis (PSHA). To reduce computational cost, CyberShake uses reciprocity: Strain Green Tensors are convolved with slip time histories for... more
Poster 200	SDOT	Groundwater Unloading in the Central Valley Modifies Crustal Stress Grace Carlson, Manoochehr Shirzaei, Susanna Werth, Guang Zhai, Chandrakanta Ojha The earth responds elastically to changes in surface mass such that when mass is added there is regional sinking of the land surface and when mass is lost there is regional uplift. These mass changes can disturb the regional stress field, which in... more
Poster 053	Seismology	Seismic Imaging of Southern California with Scattered Waves Jorge Castellanos, Robert Clayton, Voon Hui Lai The generation of a high-resolution velocity model of southern California has been the center of attention for many years. The recent growth of high-density seismic arrays has led to the development of velocity models that can now explain most of... more
Poster 134	SAFS	Ages of Prehistoric Earthquakes on the Banning Strand of the San Andreas Fault, Near North Palm Springs, California Bryan Castillo, Sally McGill, Katherine Scharer, Doug Yule, Devin McPhillips, James McNeil, Sourav Saha, Nathan Brown, Seulgi Moon The southernmost section of the San Andreas Fault (SAF) is the only section of that fault that has not ruptured in the last 200 years. It is not known whether this long quiescent period reflects a long average recurrence interval for this portion of... more
Poster 138	SAFS	High resolution imaging of the San Andreas Fault System in Baja California, Mexico using triple-difference tomography Raul Castro, Pieter-Ewald Share, Antonio Vidal-Villegas, Luis Mendoza, Yehuda Ben-Zion Understanding transform plate boundary processes and the associated seismic hazard for society requires knowledge of the geometry and material properties along major faults comprising these boundaries. High-resolution properties of the San Andreas... more
Poster 254	Ridgecrest	Three-Component Nodal Array Aftershock Deployments for the 2019 Ridgecrest Earthquake Sequence Rufus Catchings, Mark Goldman, Joanne Chan, Amir Allam, Jamison Steidl, Yehuda Ben-Zion, Coyn Criley, Zhenning Ma, Daniel Langermann, Adrian McEvilly, Daniel Mongovin To better evaluate subsurface faulting, seismic wave propagation, instrument response of seismometers, Vp and Vs structure, and seismic energy transmission from the 2019 Ridgecrest Earthquake sequence onto the Garlock fault, collaborators from the... more
Poster 315	CXM	Refining estimates of the seismic properties and geologic framework of the Mojave Desert, southern California Alan Chapman, Emma Schneider, David Lockner The Pelona-Orocopia-Rand (POR) schist of southern California exerts a primary influence on the mechanical properties of regional seismogenic zones, including the San Andreas and the Eastern California shear zone (within which the 2019 Ridgecrest... more	18210
Poster 291	EEII	A Service System for Seismic Ground Motion Parameters Zonation Map of China based on Smart Terminal and Internet Technique Bo Chen Mandatory national standard GB18306—2015 “Seismic ground motion parameters zonation map of China” has implemented since June 1, 2016, which plays an important role in people's life property safety, national economic development and social... more
Poster 262	Ridgecrest	Cascading, pulse-like ruptures during the 2019 Ridgecrest earthquakes, East California Shear Zone Kejie Chen, Jean-Philippe Avouac, SAIF AATI, Chris Milliner, Fu Zheng, Chuang Shi On July 4 2019, a Mw 6.5 earthquake struck the Searles Valley in California; 34 hours later, a larger Mw 7.1 shock ripped ~15 km to the northwest. Both ruptured previously unrecognized faults within the East California Shear Zone. Here, we present... more
Poster 183	FARM	Source characteristics of the foreshock sequence of the 2010 M7.2 El Mayor-Cucapah earthquake: implication for the triggering process Xiaowei Chen, Qimin Wu, Dongdong Yao, Zhigang Peng Foreshocks provide valuable information on the nucleation process of an upcoming large earthquake. However, the interpretation of foreshocks in terms of the underlying physical processes remains unresolved with two opposing end-member conceptual... more	19207
Poster 084	Seismology	A focal mechanism catalog for Southern California derived with deep learning algorithms Yifang Cheng, Zachary Ross, Egill Hauksson, Yehuda Ben-Zion We present an updated focal mechanism catalog for 16,341 events that occurred in southern California during 2017. The approach uses S/P amplitude ratios and first-motion P wave polarities to determine focal mechanisms with the HASH method of... more	19136
Poster 073	Seismology	Tremor or train? An attempt to discern tremor and noise using a deep convolutional neural network Lindsay Chuang, Zhigang Peng, Lijun Zhu, James McClellan Deep tectonic tremors are often characterized as non-impulsive, low signal-to-noise ratio, long-duration, and lacking in high frequency energy, which can be confused with background or anthropogenic noise. A standard technique to avoid... more	19177
Poster 274	Ridgecrest	Performance of the ShakeAlert Earthquake Early Warning System During the Ridgecrest Sequence Angela Chung, Deborah Smith, Jennifer Andrews, Maren Böse, Jeff McGuire, Men-Andrin Meier, Igor Stubailo, Richard Allen On July 4, 2019 an earthquake sequence began near Ridgecrest, CA. The sequence began with a M4.0 earthquake followed 30 minutes later by a M6.4 earthquake. Less than 36 hours later, a M7.1 earthquake shook the Los Angeles region. This mainshock was... more
Poster 058	Seismology	Ambient noise tomography of the Saudi Arabian Shield Francesco Civilini, Walter Mooney, Hani Zahran Saudi Arabia is located in a tectonically active region: spreading occurs to the west and south in the Red Sea rift and the Gulf of Aden and is accommodated by a fold and thrust belt in the Zagros mountains to the north-east. The geology in western... more

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