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STEPS: Slip time earthquake path simulations applied to the San Andreas and Toe Jam Hill Faults to redefine geologic slip rate uncertainty

Geologic slip rates are a time-averaged measurement of fault displacement calculated over hundreds to million-year time scales and are a primary input for probabilistic seismic hazard analyses, which forecast expected ground shaking in future earthquakes. Despite their utility for seismic hazard calculations, longer-term geologic slip rates represent a time-averaged measure of the tempo of strain
Authors
Alexandra Elise Hatem, Ryan D. Gold, Richard W. Briggs, Katherine Scharer, Edward H. Field

Imaging the next Cascadia earthquake: Optimal design for a seafloor GNSS- A network

The Cascadia subduction zone in the Pacific Northwest of the United States of America capable of producing magnitude ∼9 earthquakes, likely often accompanied by tsunamis. An outstanding question in this region is the degree and spatial extent of interseismic strain accumulation on the subduction megathrust. Seafloor geodetic methods combining GNSS and underwater acoustic ranging (GNSS-A) are capab
Authors
Eileen L. Evans, Sarah E. Minson, David Chadwell

Does earthquake stress drop increase with depth in the crust?

We combine earthquake spectra from multiple studies to investigate whether the increase in stress drop with depth often observed in the crust is real, or an artifact of decreasing attenuation (increasing Q) with depth. In many studies, empirical path and attenuation corrections are assumed to be independent of the earthquake source depth. We test this assumption by investigating whether a realisti
Authors
Rachel E Abercrombie, Daniel T. Trugman, Peter M. Shearer, Xiaowei Chen, Jiewen Zhang, Colin Nathanael Pennington, Jeanne L. Hardebeck, Thomas H W Goebel, Christine J Ruhl

The 6 May 1947 Milwaukee, Wisconsin, earthquake

The State of Wisconsin is not known for earthquake activity. The authoritative public‐facing U.S. Geological Survey Comprehensive Catalog of earthquakes includes only three small (magnitude < 2) earthquakes in the state, all instrumentally recorded. Although other catalogs include more events in Wisconsin, experience has shown that many types of events, such as explosions and cryoseisms, have made
Authors
Susan E. Hough

Improvements to the Third Uniform California Earthquake Rupture Forecast ETAS Model (UCERF3‐ETAS)

We describe recent improvements to the Third Uniform California Earthquake Rupture Forecast ETAS Model (UCERF3‐ETAS), which continues to represent our most advanced and complete earthquake forecast in terms of relaxing segmentation assumptions and representing multifault ruptures, elastic‐rebound effects, and spatiotemporal clustering (the latter to represent aftershocks and otherwise triggered ev
Authors
Edward H. Field, Kevin R. Milner, Morgan T. Page, William H. Savran, Nicholas van der Elst

Effect of fixing earthquake depth in ShakeAlert algorithms on performance for intraslab earthquakes

We investigate whether assuming a fixed shallow depth in the ShakeAlert network‐based earthquake early warning system is sufficient to produce accurate ground‐motion based alerts for intraslab earthquakes. ShakeAlert currently uses a fixed focal depth of 8 km to estimate earthquake location and magnitude. This is an appropriate way to reduce computational costs without compromising alert accuracy
Authors
Mika Thompson, J. Renate Hartog, Erin Wirth

Swipe left on the “big one”: Better dates for Cascadia quakes

Improving our understanding of hazards posed by future large earthquakes on the Cascadia Subduction Zone requires advancements in the methods and sampling used to date and characterize past events.
Authors
Jessie Kathleen Pearl, Lydia M. Staisch

Latest Quaternary slip rates of the San Bernardino strand of the San Andreas fault, southern California, from Cajon Creek to Badger Canyon

Four new latest Pleistocene slip rates from two sites along the northwestern half of the San Bernardino strand of the San Andreas fault suggest the slip rate decreases southeastward as slip transfers from the Mojave section of the San Andreas fault onto the northern San Jacinto fault zone. At Badger Canyon, offsets coupled with radiocarbon and optically stimulated luminescence (OSL) ages provide t
Authors
Sally F. McGill, Lewis A. Owen, Ray J. Weldon, Katherine J. Kendrick, Reed J. Burgette

NGA-subduction global ground motion models with regional adjustment factors

We develop semi-empirical ground motion models (GMMs) for peak ground acceleration, peak ground velocity, and 5%-damped pseudo-spectral accelerations for periods from 0.01 to 10 s, for the median orientation-independent horizontal component of subduction earthquake ground motion. The GMMs are applicable to interface and intraslab subduction earthquakes in Japan, Taiwan, Mexico, Central America, So
Authors
Grace Alexandra Parker, Jonathan P. Stewart, David Boore, Gail M. Atkinson, Behzad Hassani

SSA task force on diversity, equity, and inclusion: Toward a changing, inclusive future in earthquake science

In the United States, a wide variety of studies show that the geoscience community does not reflect the broader societal makeup (e.g., Velasco and Jaurrieta de Velasco, 2010; Dutt, 2020; Howley, 2020). In fact, only about 10% of all Science, Technology, Engineering, and Mathematics (STEM) Ph.D. degrees are awarded to people of color, although they represent more than a third of the population (Dut
Authors
Aaron A. Velasco, Kasey Aderhold, Richard Alfaro-Diaz, Wesley Brown, Mike Brudzinski, Margaret Fraiser, Monique M. Holt, Jim Mori, Gabriela Noriega, Katherine M. Scharer, Denise Templeton, Fabia Terra, Sherilyn Williams-Stroud

Late Holocene slip rate of the Mojave section of the San Andreas Fault near Palmdale, California

The geologic slip rate on the Mojave section of the San Andreas fault is poorly constrained, despite its importance for understanding earthquake hazard, apparent discrepancies between geologic and geodetic slip rates along this fault section, and long‐term fault interactions in southern California. Here, we use surficial geologic mapping, excavations, and radiocarbon and luminescence dating to qua
Authors
Elaine Young, Eric Cowgill, Katherine Scharer, Emery Anderson-Merritt, Amanda Keen-Zebert, Ray J. Weldon

Electrical properties of carbon dioxide hydrate: Implications for monitoring CO2 in the gas hydrate stability zone

CO2 and CH4 clathrate hydrates are of keen interest for energy and carbon cycle considerations. While both typically form on Earth as cubic structure I (sI), we find that pure CO2 hydrate exhibits over an order of magnitude higher electrical conductivity (σ) than pure CH4 hydrate at geologically relevant temperatures. The conductivity was obtained from frequency-dependent impedance (Z) measurement
Authors
Laura A. Stern, S. Constable, Ryan Lu, Wyatt L. Du Frane, J. Murray Roberts