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 101-150 of 320

SCEC ID	Category	Title and Authors	SCEC Award
Poster 220	Ridgecrest	Coseismic Variations in Slip Orientation from Curved Striations and Projectile Playa Soils during the 2019 M7.1 Ridgecrest Earthquake Elizabeth Haddon, Scott Bennett, Jason Patton, Katherine Kendrick, David Oglesby, Brian Olson, Christopher DuRoss, Alexandra Pickering Porpoising fault striations and overturned soil horizons in China Lake playa record coseismic oscillations in fault slip vector orientation during the July 5, 2019 M7.1 Ridgecrest earthquake. We investigated aspects of the dynamic rupture process by... more
Poster 270	Ridgecrest	Aftershock forecasts following the M6.4 and M7.1 Ridgecrest, California, earthquakes of July 2019 Jeanne Hardebeck, Andrew Michael, Morgan Page, Nicholas van der Elst, Michael Barall, Andrea Llenos, Eric Martinez, Sara McBride The M6.4 and M7.1 Ridgecrest earthquakes were the first significant California earthquakes since the USGS developed a new national capability for aftershock forecasting. The USGS has for decades issued aftershock forecasts in California, based on... more
Poster 263	Ridgecrest	Recent Damaging Earthquakes on Conjugate Structures in the Walker Lane: Characteristics of the The Nine Mile Ranch Sequence (2016-2019) and Comparison to the Ridgecrest Sequence of 2019 Rachel Hatch, Ken Smith, Rachel Abercrombie, Christine Ruhl, William Hammond, Ian Pierce Two damaging earthquake sequences have occurred on conjugate fault structures in the Walker Lane tectonic zone in the last 3 years. The Ridgecrest sequence (July 2019, M6.4 and M7.1) in the eastern California Shear Zone, the southern part of the... more
Poster 057	Seismology	Estimation of shear wave velocity structure using joint inversion of surface-wave phase and group velocities derived from ambient noise recordings Takumi Hayashida, Toshiaki Yokoi, Mukunda Bhattarai The usual geophysical exploration method using ambient noise (microtremor) array is focusing on deriving phase velocity dispersion curves of longer wavelength (2-10 times of sensor-to-sensor distance) Rayleigh wave and estimating S-wave velocity... more
Poster 242	Ridgecrest	Postseismic deformation models for the July 2019 Ridgecrest earthquakes: Applications of the SCEC Community Rheology Model Elizabeth Hearn, Charles Williams We are developing finite-element models to forward calculate early postseismic deformation following the Ridgecrest earthquake sequence. Our goals are to (1) compare modeled surface velocities with postseismic velocity data as they become available... more	19155, 18193
Poster 170	FARM	Earthquake cycles on a self-similar rough fault: The importance of the minimum roughness wavelength Elias Heimisson Faults in nature demonstrate fluctuations from planarity at most length scales that are relevant for earthquake dynamics. These fluctuations may influence all stages of the seismic cycle; earthquake nucleation, propagation, arrest, and inter-seismic... more
Poster 143	SAFS	Multicomponent Model of Crustal Stress at Cajon Pass, Southern California with Implications for Stress Field Heterogeneity Elliott Helgans, Karen Luttrell, Bridget Smith-Konter, Liliane Burkhard Earthquake processes in plate boundary settings are chiefly controlled by the in situ crustal stress field. Knowledge of the relative importance of various active processes acting on a fault system is necessary to understand the mechanics of... more	18150, 19070
Poster 035	EFP	Revisiting the Earthquake Interevent Time Distribution and the Poisson Model with the QTM Catalog for Southern California Erin Hightower, Jean-Philippe Avouac Existing probabilistic seismic hazard models often assume a stationary Poisson process. Such a process is often argued to be insufficient for the largest earthquakes, which have a greater impact on crustal stresses and seismicity patterns and may... more
Poster 313	CXM	Evaluation and Adjustments of the USGS San Francisco Bay Area Velocity Model: Special Focus on the East Bay Evan Hirakawa, Brad Aagaard The current version of the USGS Bay Area Velocity Model is a 3D representation of the seismic velocity structure in the San Francisco Bay region. The model has been shown to successfully reproduce many aspects of ground motion and wave propagation... more
Poster 042	Seismology	Time-dependent earthquake tomography in Southern California Jing Hu, Hongrui Qiu, Pieter-Ewald Share, Jiawei Qian, Haijiang Zhang, Yehuda Ben-Zion Temporal changes of seismic velocities have been determined through analyses of earthquake and ambient noise data in Southern California and elsewhere, but there is limited understanding of the spatial distribution and amplitudes of these changes.... more
Poster 007	GM	Modeling of Empirical Transfer Functions including 3D Velocity Structure Zhifeng Hu, Daniel Roten, Kim Olsen, Steven Day Site response can be an important factor in estimating seismic hazard. However, conventional simplified modeling of site amplification with assumptions of plane SH waves propagating vertically through layered homogeneous media (SH1D) often poorly... more
Poster 260	Ridgecrest	Spatio-temporal foreshock evolution of the 2019 M 6.4 and M 7.1 Ridgecrest, California Earthquakes Hui Huang, Roland Bürgmann, Lingsen Meng, Kang Wang, Baptiste Rousset The 2019 M 7.1 Ridgecrest, California earthquake ruptured in a complex multi-segment fault system in the Eastern California Shear Zone. The mainshock was preceded by an intense foreshock sequence, including a large M 6.4 event. The aftershocks of... more
Poster 224	Ridgecrest	Airborne lidar and electro-optical imagery along surface ruptures of the 2019 Ridgecrest earthquake sequence, southern California Kenneth Hudnut, Benjamin Brooks, Katherine Scharer, Janis Hernandez, Timothy Dawson, Michael Oskin, Ramon Arrowsmith, Kelly Blake, Stephan Bork, Matthew Boggs, Craig Glennie, Juan Carlos Fernandez-Diaz, Abhinav Singhania, Darren Hauser Surface rupture from the Ridgecrest earthquake sequence occurred on July 4 along the 17 km long, northeast-southwest oriented, left-lateral zone of faulting associated with the M 6.4 foreshock. Offset across several strands forming a 165 meter-wide... more
Poster 276	Ridgecrest	The first few days of the 2019 Ridgecrest earthquake sequence Benjamin Idini, Mark Simons, Minyan Zhong, Oliver Stephenson, Zachary Ross, Eric Fielding, Sang-Ho Yun, Egill Hauksson, Chris Milliner, Angelyn Moore, Zhen Liu A nearly 20-year-long hiatus in significant seismic activity in southern California ended on July 4, 2019 with a sequence of earthquakes near the city of Ridgecrest, CA. This sequence included a M6.4 foreshock followed by a M7.1 mainshock nearly... more
Poster 074	Seismology	Thermally Induced Deformation and Seismicity Kyungjae Im, Jean-Philippe Avouac Thermal stress perturbation due to geothermal operation is slow, but the associated stress changes can be significant and could contribute substantially to fracturing, reactivation of pre-existing faults and surface deformation. Furthermore, the... more
Poster 108	Geology	Late Holocene Rupture History of the South-Central San Andreas Fault at Van Matre Ranch, California Nick Inserra, Sinan Akciz Characterizing long-term rupture patterns for active faults is integral to understanding fault dynamics and evaluating seismic hazard. Even for the south-central San Andreas Fault (SAF), sites with well-constrained past earthquakes evidence are few... more
Poster 316	CXM	How certain are regional strength envelopes in Southern California? Kristel Izquierdo, Laurent Montesi, William Holt, Alireza Bahadori, William Shinevar Comparing different estimates of viscosity in the lithosphere can lead to a more robust understanding of the geological origin of rheological variations in the study area. Similar patterns of viscosity increase confidence in the validity of the... more
Poster 259	Ridgecrest	Preliminary seismological analyses of 2019 Mw 6.4 Searles Valley and Mw 7.1 Ridgecrest California earthquakes Chen Ji, Ralph Archuleta, Kenichi Tsuda, Scott Condon We have studied the co-seismic rupture processes of the 2019 Mw 6.4 Searles Valley and Mw 7.1 Ridgecrest earthquakes by joint inverting seismic waveforms recorded by local and teleseismic stations, and co-seismic geodetic displacements estimated... more	19079
Poster 051	Seismology	Shallow velocity structure of Los Angeles Basin from ambient noise tomography with dense seismic arrays Zhe Jia, Robert Clayton It is important to understand the lateral variation of the sediment structure in the Los Angeles (LA) basin because the shallow velocity structure can amplify strong ground motions. The existing sediment models in the Los Angeles Basin are usually... more
Poster 127	Geology	Seismogenic structure of the 2017 Ms6.9 Milin earthquake in Tibet Tian Jian The Ms6.9 Milin earthquake occurred at November 18,2017. The focal mechanism shows that the Milin earthquake is mainly caused by thrust structures. The relocated result shows that the aftershocks concentrate in a narrow stripe along the northeast... more
Poster 196	SDOT	Time-dependent deformation and seismicity in the Imperial Valley, California Junle Jiang, Rowena Lohman The Imperial Valley region in Southern California straddles the transitional zone from the southern terminus of the San Andreas fault to a series of right-lateral faults and extensional structures that extend to the south of the US-Mexico border.... more
Poster 275	Ridgecrest	Rupture models of the 2019 M6.4-7.1 Ridgecrest earthquakes constrained by space geodetic data and aftershock locations Zeyu Jin, Yuri Fialko The July 2019 Ridgecrest earthquake sequence includes two major events, the M6.4 foreshock and M7.1 main shock that ruptured the nearly orthogonal intersecting strike-slip faults within one day of each other. Analysis of space geodetic observations... more	19234
Poster 065	Seismology	Classifying emergent and impulsive signals in continuous seismic waveforms Christopher Johnson, Yehuda Ben-Zion, Haoran Meng, Frank Vernon Proper classification of different emergent and impulsive noise signals is critical for detection of microearthquakes and developing an improved understanding of ongoing weak ground motions. Tectonic events occupy about 1% of recorded seismic... more
Poster 178	FARM	Inversion for the Higher-Degree Moment Tensors of the 2016 Mw 7.8 Kaiköura Earthquake Alan Juarez, Thomas Jordan The Mw7.8 Kaikoura, New Zealand, earthquake of 2016 is one of the most complex earthquakes ever recorded. It ruptured more than twenty crustal faults with different strikes, dips, and rakes, as well as the subduction megathrust beneath New Zealand.... more
Poster 191	SDOT	Horizontal Principal Stress Orientations Near Long Beach, California from Borehole Breakouts Justin Kain, Patricia Persaud, Joann Stock We present new results on crustal stress in the Wilmington oil field near Long Beach, California. The Wilmington field is bordered by major fault systems such as the THUMS-Huntington Beach and the Palos Verdes faults, and is a target of our... more	16062
Poster 165	FARM	Fault Stabilization by Dilatant Hardening in Granular Rocks Taka Kanaya Triaxial compression experiments were conducted on Fontainebleau sandstone with initial porosities of 4 and 6% at a constant effective pressure of 70 MPa (produced by various combinations of confining and pore pressures), a strain rate of 10-5/... more	19218
Poster 097	Geology	Differential uplift of fluvial and marine terraces across the Santa Ynez River fault, Santa Barbara County, California Clay Kelty, Nate Onderdonk, Richard Behl, Antonio Garcia The Santa Ynez River fault is a major regional structure along the central California coast that separates the Western Transverse Ranges and the Santa Maria Basin. The fault is interpreted as a steep, south-dipping, oblique left-lateral reverse... more
Poster 217	Ridgecrest	Geologic observations of surface fault rupture associated with the Ridgecrest M6.4 and M7.1 earthquake sequence by the Ridgecrest Rupture Mapping Group Katherine Kendrick, Sinan Akciz, Stephen Angster, Jean-Philippe Avouac, Jeffrey Bachhuber, Scott Bennett, Kelly Blake, Stephan Bork, Benjamin Brooks, Paul Burgess, Colin Chupik, Timothy Dawson, Michael DeFrisco, Jaime Delano, Stephen DeLong, James Dolan, Christopher DuRoss, Todd Ericksen, Erik Frost, Ryan Gold, Nicholas Graehl, Elizabeth Haddon, Alexandra Hatem, Janis Hernandez, Christopher Hitchcock, Kenneth Hudnut, Rich Koehler, Ozgur Kozaci, Tyler Ladinsky, Christopher Madugo, Maxime Mareschal, Devin McPhillips, Chris Milliner, Alex Morelan, Johanna Nevitt, Brian Olson, Salena Padilla, Jason Patton, Belle Philibosian, Alexandra Pickering, Ian Pierce, Daniel Ponti, Cynthia Pridmore, Carla Rosa, Nathaniel Roth, Katherine Scharer, Gordon Seitz, Ellie Spangler, Brian Swanson, Kate Thomas, Jessica Thompson Jobe, Jerry Treiman, Alana Williams, Michael Oskin Surface rupture associated with the July 2019 Ridgecrest earthquake sequence initiated with a M6.4 earthquake on 4 July 2019 that ruptured along a NE-striking, sinistral fault zone. The M7.1 earthquake, the largest of the sequence, followed on 5... more
Poster 101	Geology	Late Quaternary deformation and recency of faulting of the northernmost San Jacinto fault zone, and implications for slip transfer to San Andreas fault Drake Kerr, Nate Onderdonk, Paula Figueiredo Paleoseismic and geologic data on the southern San Andreas fault (SAFZ) show that there is a significant difference in earthquake recurrence and slip rate on the fault north and south of Cajon Pass. The northern end of the San Jacinto fault zone (... more	18124
Poster 202	Geodesy	Deep slow-slip events promote seismicity in northeastern Japan subduction zone Mostafa Khoshmanesh, Manoochehr Shirzaei, Naoki Uchida The sliding movement between oceanic and crustal plates in subduction zones is accommodated through both rapid stick-slip earthquakes and quasi-static or transient aseismic slip. On northeastern Japan subduction zone (NJSZ), aseismic transients,... more
Poster 061	Seismology	On the Variability of Earthquake Ground Motion from the Sage Brush Flats High Density Array in Southern California Debi Kilb, Christopher Johnson, Annemarie Baltay, Frank Vernon We explore the spatial variability in peak ground velocity (PGV) at the southern California Sage Brush Flats (SGB) study area, along the Clark branch of the San Jacinto Fault zone. The SGB dense network array spans a 0.6 km by 0.6 km footprint and... more
Poster 001	GM	Source and Site Spectral Inversion for κ0 Computation in the Bay Area Elias King, Alexis Klimasewski, Valerie Sahakian, Annemarie Baltay Site characterization is an important component of understanding ground motion, and is one of the only parameters that can be constrained prior to an earthquake. κ0, the attenuation of high frequency energy near the site (Anderson & Hough, 1984... more
Poster 124	Geology	Bedrock structural controls on the propagation of multi-fault earthquake ruptures and their environmental effects Tamarah King, Mark Quigley, Dan Clark Analyses of geological and geophysical data from ten moderate magnitude (Mw 4.7 – 6.6) historical surface-rupturing earthquakes in cratonic Australia indicate that bedrock structure controlled the orientation and geometry of their seismogenic... more
Poster 021	GM	Comparing artificial neural networks with traditional ground-motion models for small magnitude earthquakes in Southern California Alexis Klimasewski, Valerie Sahakian, Amanda Thomas Earthquake ground motions are the superposition of source mechanics, wave propagation, and near site effects which cannot be fully known a priori. Statistically-based ground-motion models (GMMs) are by far the most widely-used method to estimate... more
Poster 018	GM	Strong Ground Motions Simulations for Dunedin Anna Kowal We present our on-going QuakeCoRE-funded work on strong motion seismology for Dunedin–Mosgiel area, focusing on ground motion simulations for the Dunedin Central Business District (CBD). Source modelling and ground motion simulations are being... more
Poster 221	Ridgecrest	Rapid post-earthquake reconnaissance and paleoseismic trenching preliminary results for the M6.4 and M7.1 Ridgecrest earthquake sequence, Southern California Ozgur Kozaci, Christopher Madugo, Jeffrey Bachhuber, Christopher Hitchcock, Albert Kottke, Kaherine Herr A sequence of surface rupturing events started with a magnitude M6.4 earthquake on July 4th, 2019 near Ridgecrest, California. The coseismic deformation associated with this event is identified by an approximately 22-km-long, east-west oriented... more
Poster 284	Seismology	Parametric Estimation of the Local Stress Field in Southern Kansas Kayla Kroll, Keith Richards-Dinger, Josha White, James Dieterich Accurate determination of state of stress at a field site is key in order to evaluate the geomechanical impacts of any industrial operation that involves injection of fluids into the deep subsurface. Direct borehole measurements of the orientation... more
Poster 152	FARM	The Cajon Pass Earthquake Gate: the effect of topography on dynamic rupture models Christodoulos Kyriakopoulos, Baoning Wu, David Oglesby One of the most distinctive topographic features in Southern California is the asymmetric disposition of the topography around Cajon Pass. Southeast of the Pass, the San Bernardino range is on the North side of the fault, whereas a short distance to... more	19223
Poster 012	GM	Analyzing Shallow Basin Effects in Los Angeles Basin using 3D Simulations and Dense Array Analysis Voon Hui Lai, Robert Graves, Zhongwen Zhan, Chunquan Yu, Donald Helmberger Ground motions in the Los Angeles Basin during a potential large earthquake such as a San Andreas rupture are modulated by several factors including earthquake source magnitude and rupture length, path effects into the LA Basin, and local basin... more	18128
Poster 149	FARM	Modeling the low-stress, low-heat operation of mature faults Valere Lambert, Nadia Lapusta Numerous lines of evidence, including observations of heat flow, steep angles between largest principal stress and fault traces, and the geometry of thrust-belt wedges, suggest that the shear resistance on mature faults must be low ( < 20 MPa).... more	18174, 19085
Poster 063	Seismology	Broadband Ground-Motion Simulation for the Korean Peninsula Jaejoon Lee, Yonghyun Chung, Kangryul Lee, Changsoo Shin We present our on-going work on developing a broadband ground motion simulation platform for the Korean Peninsula funded by Korea Electric Power Corporation (KEPCO). The Korean Peninsula is generally considered stable with low to moderate intraplate... more
Poster 020	GM	Hybrid Broadband Ground Motion Simulation Validation of New Zealand Earthquakes with an Updated 3D Velocity Model and Modified Simulation Methodology Robin Lee, Brendon Bradley, Peter Stafford, Robert Graves, Adrian Rodriguez-Marek Over the past 30 years there has been significant research to advance physics-based ground motion simulations via improvement of the simulation methodologies, and refinement of earthquake source, crustal velocity, and site effects modelling.... more
Poster 318	CXM	Terrane Boundary Definition for the Borderland Geologic Framework SCEC5 Community Rheology Model Mark Legg, Marc Kamerling A Geologic Framework (GF) for the offshore southern California region (Borderland) is developed for the Community Rheology Model. The Borderland region of fault-bounded basins and ridges formed during the Miocene evolution of the PAC-NAM transform... more	19205
Poster 211	Geodesy	Testing Structural Model Predictions Against Geodetic Data in the Western Transverse Ranges, Southern California Yuval Levy, Scott Marshall, Thomas Rockwell, John Shaw In the Western Transverse Ranges of southern California, paleoseismic evidence has documented large uplift events along the Ventura-Pitas Point fault system. Given the number of competing models in the region we conducted a comprehensive structural... more	19189
Poster 173	FARM	Exploring the effect of timing on the source properties of intershocks produced at asperities in a rate-and-state fault model Junheng Li, Natalie Schaal, Semechah K.Y. Lui Despite the countless observations of foreshocks before many large earthquakes, the mechanism responsible for their occurrence remains under debate. Moreover, the physical relationship between foreshocks and mainshocks remains uncertain. In this... more
Poster 054	Seismology	S wave velocity model from ambient-noise surface-wave tomography in the San Gabriel and San Bernardino Basins Yida Li, Robert Clayton, Zhe Jia The velocity structure of San Gabriel basin and San Bernardino Basin in the northern part of the Los Angeles region are of great importance for the earthquake hazard evaluation, as they have the potential to focus seismic energy into the Los Angeles... more
Poster 180	FARM	Structural Relationship between Rupture Zones in a Sequence of Earthquakes Viewed by Fault-Zone Trapped Waves Yong-Gang Li, J-R Su, T-C Chen, P. Wu, Gregory De Pascale, M. Quigley, D. Gravely We used fault-zone trapped waves (FZTW) to image rupture zones of the 20018 M8 Wenchuan and 2013 M7 Lushan earthquakes occurred on the Longmenshan Fault (LSF) in Sichuan, China, and rupture zones of the 2010 M7.1 Darfield and 2011 M6.3 Christchurch... more
Poster 207	Geodesy	Characterizing creeping faults using InSAR: a case study of the Xianshuihe Fault Yuexin Li, Roland Bürgmann The Xianshuihe Fault is located at the eastern boundary of the Tibetan Plateau and is one of the most active faults in China. It is associated with substantial seismic potential, with more than 20 Mw>6 earthquakes since 1700. The fault has been... more
Poster 309	CEO	30 Year Forecast for the Current California Earthquake Drought Ruben Li Wu, Gisselle Mondragon, Terri Tang, Laura Davey, Vanessa Carpio, Amabel Teca, Malka Lazerson, Jerlyn Swiatlowski, Kevin Milner, Scott Callaghan, Thomas Jordan Since 1906, California’s San Andreas Fault System has not produced a M7.0+ earthquake in over 100 years. After over a century of dormancy, the San Andreas Fault is approaching its recurrence rupture interval of 140 years (Wald et al., 2019). In... more
Poster 277	Ridgecrest	Co-seismic rupture process of the large 2019 Ridgecrest earthquakes from joint inversion of geodetic and seismological observations Chengli Liu, Thorne Lay, Emily Brodsky, Kelian Dascher-Cousineau, Xiong Xiong On 4 July 2019 and 6 July 2019, two large strike-slip earthquakes with W-phase moment magnitudes MWW 6.5 (foreshock) and MWW 7.1 (mainshock) struck the Eastern California Shear Zone, northeast of Ridgecrest. The faulting geometry and kinematic co-... more

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