Betsy Madden, San Jose State University Seismic hazard assessments currently depend on fault slip rates, the cumulative offset over many earthquakes along individual faults, to determine the probability of earthquakes of a certain magnitude over a certain time period and potential ground motions. Geologic fault slip rates are estimated by a combination of field and laboratory techniques. Such data can be generated synthetically with mechanical models that capture slip rate variations along complex, three-dimensional fault networks. I will discuss opportunities provided by these synthetic data ..read more

James Atterholt, USGS Observations of broad-scale lithospheric structure and large earthquakes are often made with sparse measurements and are low resolution. This makes interpretations of the processes that shape the lithosphere fuzzy and nonunique. Distributed Acoustic Sensing (DAS) is an emergent technique that transforms fiber-optic cables into ultra-dense arrays of strainmeters, yielding meter-scale resolution over tens of kilometers for long recording periods. Recently, new techniques have made probing fiber-measured earthquake wavefields for signatures of large-scale deformation and dyn ..read more

Doron Morad, University of California, Santa Cruz In natural fault surfaces, stresses are not evenly distributed due to variations in the contact population within the medium, causing frictional variations that are not easy to anticipate. These variations are crucial for understanding the kinematics and dynamics of frictional motion and can be attributed to both the intact material and granular media accommodating the principal slip zone. Here, I explore the effects of heterogeneous frictional environments using two different approaches: fracture dynamics on non-mobilized surfaces and granular ..read more

Cassie Hanagan, USGS Advancing our understanding of earthquake processes inevitably pushes the bounds of data resolution in the spatial and temporal domains. This talk will step through a series of examples leveraging two relatively niche geodetic datasets for understanding portions of the earthquake cycle: (1) temporally dense and sensitive borehole strainmeter (BSM) data, and (2) spatially dense sub-pixel image correlation displacement data. More specifically, I will detail gap-filling benefits of these two datasets for different earthquakes. BSMs respond to a frequency of deformation that b ..read more

Evan Hirakawa, USGS Northern California, specifically the San Francisco Bay Area, is a great place to study earthquake hazards and risk, due to its dense population centers surrounded by active faults, as well as complex geology that strongly influences earthquake ground motions. Computer simulations of seismic wave propagation which can incorporate 3D models of the subsurface properties and complex faulting behavior are good tools for studying seismic hazard, but ultimately require more development before unlocking full potential; specifically, the 3D seismic velocity models need to be furthe ..read more

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 understanding of ground motion variability arising from source, path, and site effects. First ..read more

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 resilience goals. Recovery-based design has emerged as a new paradigm to address this gap by explicitly designing buildings ..read more

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 efforts. In this talk, I will present a detailed analysis of the dynamic range, and how it impacts EEW: where does ..read more

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 link effects of direct fluid injection to rupture behavior. Comparison between the nucleation of dynamic even ..read more

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 machine learning techniques to obtain a close approximation of simulated seismic wavefields that can be solved rapi ..read more