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, creep rates consistently increased along the whole Hayward fault. Accelerated fault creep associated with M > 4 ..read more

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, EEW message delivery receipts, as well as triggered acceleration waveforms using the onboard smartphone acceleromete ..read more

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 on our recent efforts to study shallow microearthquakes in several regions of the SEUS using dense nodal seismic net ..read more

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 subsurface-parameter inversion applications. These workflows seek to match all the waveforms present within active seismic data or s ..read more

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 question remains why some aftershocks occur in the stress shadows. I examine three hypotheses: (1) A ..read more

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 of earthquake waveforms into low-dimensionality “fingerprints” that can the ..read more

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 earthquakes in the interior of the Antarctic continent in the past two decades according to the International Seismolog ..read more

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 geodetic, field, and experimental observations to evaluate the relationship between slip and off-fault deformation duri ..read more

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 to over 1.5 million catalog earthquakes in California from 1980 to 2021, yielding high-quality focal mechanisms for m ..read more

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 zone plate interface using microseismicity patterns. Knowledge of coupling provides information about the s ..read more