Omar Issa, ResiQuant (Co-Founder)/Stanford University A study by FEMA suggests that 20-40% modern code-conforming buildings would be unfit for re-occupancy following a major earthquake (taking months or years to repair) and 15-20% would be rendered irreparable. The increasing human and economic exposure in seismically active regions emphasize the urgent need to bridge the gap between national seismic design provisions (which do not consider time to recovery) and community...

Martijn van den Ende, Université Côte d'Azur Already for several years it has been suggested that Distributed Acoustic Sensing (DAS) could be a convenient, low-cost solution for Earthquake Early Warning (EEW). Several studies have investigated the potential of DAS in this context, and demonstrated their methods using small local earthquakes. Unfortunately, DAS has a finite dynamic range that is easily exceeded in the near-field of large earthquakes, which severely hampers any EEW...

Sara Beth Cebry, U.S.G.S. luid injection decreases effective normal stress on faults and can stimulate seismicity far from active tectonic regions. Based on earthquake nucleation models and measured stress levels, slip will be stable, aseismic, and limited to the fluid pressurized region—contrary to observed increases in seismicity. To understand how fluid injection effects earthquake initiation, rupture, and termination, I used large-scale laboratory faults to experimentally...

John Rekoske, University of California San Diego Rapidly estimating the ground shaking produced by earthquakes in real-time, and from future earthquakes, are important challenges in seismology. Numerical simulations of seismic wave propagation can be used to estimate ground motion; however, they require large amounts of computing power and are too slow for real-time problems, even with modern supercomputers. Our aim is to develop a method using both high-performance computing and...

Haiyang Kehoe, USGS Seismograms contain information of an earthquake source, its path through the earth, and the local geologic conditions near a recording site. Ground shaking felt on Earth’s surface is modified by each of these contributions–the spatiotemporal evolution of rupture, three-dimensional subsurface structure, and site conditions all have a substantial impact on hazards experienced by exposed populations. In this talk, I highlight three studies that have improved our...

Tara Nye, USGS Models of earthquake ground motion (both simulations and ground-motion models) can be likened to a puzzle with three primary pieces representing the earthquake source, site conditions, and source-to-site path. Early versions of these models were developed using average behavior of earthquakes across a variety of regions and tectonic environments. Although informative, such models do not capture the unique source, path, and site effects that are expected to have a...

Rashid Shams, University of Southern California Site response in sedimentary basins is partially governed by mechanisms associated with three-dimensional features. This includes the generation of propagating surface waves due to trapped and refracted seismic waves, focusing of seismic energy due to basin shape and size, and resonance of the entire basin sediment structure. These mechanisms are referred to as basin effects and they lead to a significant increase in the amplitude...

Amy Williamson, University of California Berkeley Alerts sent through earthquake early warning (EEW) programs provide precious seconds for those alerted to take simple protective actions to mitigate their seismic risk. Programs like ShakeAlert have been providing alerts for felt earthquakes across the west coast of the US for almost 5 years. Earthquakes are also one part of a multihazard system and can trigger secondary natural hazards such as tsunamis and landslides. However in...

James Biemiller, USGS An unresolved aspect of tsunami generation in great subduction earthquakes is the offshore competition between coseismic deformation mechanisms, such as shallow megathrust slip, slip on one or more splay faults, and off-fault plastic deformation. In this presentation, we first review results from data-constrained 3D dynamic rupture modeling of an active plate-boundary-scale low-angle normal fault, the Mai’iu fault, that show how stress, fault structure, and...

Jaeseok Lee, Brown University Field observations indicate that fault systems are structurally complex, yet fault slip behavior has predominantly been attributed to local fault plane properties, such as friction parameters and roughness. Although relatively unexplored, emerging observations highlight the importance of fault system geometry in the mechanics governing earthquake rupture processes. In this talk, I will discuss how the geometrical complexities of fault networks impact...

Thomas Lee, Harvard University Since the first seismograms were recorded in the late 19th century, the seismological community has accumulated millions of ground motion records on both paper and film. While almost all analog seismic recording ended by the late 20th century, replaced by digital media, the still-extant archives of paper and film seismograms are invaluable for many ongoing scientific applications. This long-running record of ground motion is crucial for developing...

Ross Maguire, University of Illinois Urbana-Champaign Seismic source parameters – including hypocentral locations and focal mechanism solutions – provide the most direct constraints for understanding tectonic stresses and deformation processes within planetary interiors. The SEIS (Seismic Experiment for Interior Structure) seismometer deployed by the InSight mission to Mars detected and located approximately 40 high-quality marsquakes. However, inferences about the present-day...

Roland Burgmann, University of California Berkeley Decadal changes in aseismic fault slip rate on partially coupled faults reflect long-term changes in fault loading and/or fault-frictional properties that can be related to earthquake cycle processes. We consider constraints on aseismic fault slip rates from historical alignment array measurements, InSAR measurements since 1992, and repeating micro-earthquakes since 1984 along the Hayward fault, California. During recent decades,...

Savvas Marcou, University of California Berkeley MyShake is a free smartphone application, developed at UC Berkeley, that serves as one of the main delivery mechanisms for earthquake early warning (EEW) alerts issued to the US West Coast by the USGS ShakeAlert system. While it is most well-known for delivering alerts to the public, MyShake was originally conceived as a platform for crowdsourcing earthquake data. MyShake currently collects crowdsourced shaking experience reports,...

Zhigang Peng, Georgia Institute of Technology Earthquakes are not frequent in the Southeastern United States (SEUS), but they do occur in areas with long-term seismic activity and in new regions with no clear seismic history. Most of these earthquakes have relatively small magnitudes (less than 1) and are therefore not well recorded by the current seismic network. Some are extremely shallow, with hypocenters less than a few kilometers deep. In this talk, I will provide an update...

Ettore Biondi, California Institute of Technology Traveltime-based tomographic methods have been extensively explored and employed by researchers since the 80s. Such algorithms have been successfully applied to various geophysical applications, ranging from seismic exploration to global to regional seismological scales. However, given the advancements in computational architectures over the last 20 years, full-waveform methodologies are now dominating most of the...

Janet Watt, U.S. Geological Survey Investigating the geologic record of shallow megathrust behavior is imperative for estimating the earthquake hazard and tsunamigenic potential along the Cascadia subduction zone. Ship-borne sparker seismic imaging and multibeam mapping is integrated with targeted autonomous underwater vehicle (AUV) bathymetry and sub-bottom data to document along-strike variability in seafloor morphology and deformation mode along the Cascadia subduction zone...

Jeanne Hardebeck, U.S. Geological Survey Aftershock triggering is commonly attributed to static Coulomb stress changes from the mainshock. A Coulomb stress increase encourages aftershocks in some areas, while in other areas termed “stress shadows” a decrease in Coulomb stress suppresses earthquake occurrence. While the predicted earthquake rate decrease is rarely seen, lower aftershock rates are observed in the stress shadows compared to stress increase regions. However, the...

Theresa Sawi, U.S. Geological Survey Repeating earthquakes sequences are widespread along California’s San Andreas fault (SAF) system and are vital for studying earthquake source processes, fault properties, and improving seismic hazard models. In this talk, I’ll be discussing an unsupervised machine learning‐based method for detecting repeating earthquake sequences (RES) to expand existing RES catalogs or to perform initial, exploratory searches. This method reduces spectrograms...

Andres Pena Castro, University of New Mexico The seismicity detected in the Antarctic continent is low compared with other continental intraplate regions of similar size. The low seismicity may be explained by (i) insufficient strain rates to generate earthquakes, (ii) scarcity of seismic instrumentation for detecting relatively small earthquakes, (iii) lack of comprehensive data mining for tectonic seismicity, or a combination of all the aforementioned. There have been ∼ 200...

Zachary Smith, University of California Berkley Intense dynamic stresses during earthquakes can activate numerous subsidiary faults and generate off-fault damage that alters fault properties and can impact the source processes and rupture dynamics of future earthquakes. Distinguishing how much damage accumulates during a single earthquake versus multiple earthquake cycles and determining how the magnitude of earthquakes impacts off-fault damage remains challenging. We combine...

Yifang Cheng, Tongji University, Shanghai Earthquake focal mechanisms offer insights into the architecture, kinematics, and stress at depth within fault zones, providing observations that complement surface geodetic measurements and seismicity statistics. We have improved the traditional focal mechanism calculation method, HASH, through the incorporation of machine learning algorithms and relative earthquake radiation measurements (REFOC). Our improved approach has been applied...

Travis Alongi, U.S. Geological Survey Many of the world’s most damaging faults are offshore, presenting unique challenges and opportunities for studying earthquakes and faults. This talk explores how earthquake-generated (passive) and human-made (active) marine seismic methods improve our knowledge of on-fault slip behavior and off-fault damage. The first part of my talk explores coupling along the poorly resolved shallow offshore portion of the southernmost Cascadia subduction...

Thomas Rockwell, San Diego State University The Salton Basin was free of significant water between about 100 BCE and 950 CE but has filled to the sill elevation of +13 m six times between ca 950 and 1730 CE. Based on a dense array of cone penetrometer (CPT) soundings across a small sag pond, the Imperial fault is interpreted to have experienced an increase in earthquake rate and accelerated slip in the few hundred years after re-inundation, an observation that is also seen on the...