Publications
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Apparent non-double-couple components as artifacts of moment tensor inversion
Compilations of earthquake moment tensors from global and regional catalogs find pervasive non-double-couple (NDC) components with a mean deviation from a double-couple (DC) source of around 20%. Their distributions vary only slightly with magnitude, faulting mechanism, or geologic environments. This consistency suggests that for most earthquakes, especially smaller ones whose rupture...
Authors
Boris Rösler, Seth Stein, Adam T. Ringler, Jiří Vackár
Preliminary implications of viscoelastic ray theory for anelastic seismic tomography models
The recent developments in general viscoelastic ray theory provide a rigorous mathematical framework for anelastic seismic tomography. They provide closed‐form solutions of forward ray‐tracing and simple inverse problems for anelastic horizontal and spherical layered media with material gradients. They provide ray‐tracing computation algorithms valid for all angles of incidence that...
Authors
Roger D. Borcherdt
Inbuilt age, residence time, and inherited age from radiocarbon dates of modern fires and late Holocene deposits, Western Transverse Ranges, California
Radiocarbon dates of sedimentary deposits include the elapsed time between formation of the organic material and deposition at the sample site, known as the inherited age. Long inherited ages reduce the accuracy of estimates of the timing of depositional events used to infer paleoclimate change, fire histories, and paleoearthquake timing. An inherited age distribution combines the...
Authors
Katherine M. Scharer, Devin McPhillips, Jenifer Amy Leidelmeijer, Matthew Kirby
Performance-based earthquake early warning for tall buildings
The ShakeAlert Earthquake Early Warning (EEW) system aims to issue an advance warning to residents on the West Coast of the United States seconds before the ground shaking arrives, if the expected ground shaking exceeds a certain threshold. However, residents in tall buildings may experience much greater motion due to the dynamic response of the buildings. Therefore, there is an ongoing...
Authors
S. Farid Ghahari, Khachik Sargsyan, Grace Alexandra Parker, Dan Swensen, Mehmet Çelebi, Hamid Haddadi, Ertugrul Taciroglu
Noise constraints on global body‐wave measurement thresholds
Intermediate sized earthquakes (≈M4–6.5) are often measured using the teleseismic body‐wave magnitude (𝑚b). 𝑚b measurements are especially critical at the lower end of this range when teleseismic waveform modeling techniques (i.e., moment tensor analysis) are difficult. The U.S. Geological Survey National Earthquake Information Center (NEIC) determines the location and magnitude of all...
Authors
Adam T. Ringler, David C. Wilson, Paul S. Earle, William L. Yeck, David B. Mason, Justin T. Wilgus
Seismic attenuation and stress on the San Andreas Fault at Parkfield: Are we critical yet?
The Parkfield transitional segment of the San Andreas Fault (SAF) is characterized by the production of frequent quasi-periodical M6 events that break the very same asperity. The last Parkfield mainshock occurred on 28 September 2004, 38 years after the 1966 earthquake, and after the segment showed a ∼22 years average recurrence time. The main reason for the much longer interevent period...
Authors
Luca Malagnini, Robert M. Nadeau, Thomas E. Parsons
Summary of Creepmeter Data from 1980 to 2020—Measurements Spanning the Hayward, Calaveras, and San Andreas Faults in Northern and Central California
This report is an update to the presentation by Schulz (1989) introducing potential users to the creepmeter data collected between the publication of Schulz’s report and mid-2020. The creepmeter network monitors aseismic, surface slip at various locations on the Hayward, Calaveras, and San Andreas Faults in northern and central California. There are different designs of creepmeters and...
Authors
John Langbein, Roger G. Bilham, Hollice A. Snyder, Todd Ericksen
Submarine avalanche deposits hold clues to past earthquakes
Earthquakes and other natural events sometimes shake the seafloor near coastlines severely enough to cause underwater avalanches that rush down steep slopes, scouring the seabed and carrying sediment to greater depths. These fast-moving sediment-laden flows, called turbidity currents, have at times damaged underwater infrastructure like pipelines and communications cables, as they did...
Authors
Valerie J. Sahakian, Debi Kilb, Joan S. Gomberg, Nora M. Nieminski, Jake Covault
Distinct yet adjacent earthquake sequences near the Mendocino Triple Junction: 20 December 2021 Mw 6.1 and 6.0 Petrolia, and 20 December 2022 Mw 6.4 Ferndale
Two earthquake sequences occurred a year apart at the Mendocino Triple Junction in northern California: first the 20 December 2021 �w 6.1 and 6.0 Petrolia sequence, then the 20 December 2022 �w 6.4 Ferndale sequence. To delineate active faults and understand the relationship between these sequences, we applied an automated deep‐learning workflow to create enhanced and relocated...
Authors
Clara Yoon, David R. Shelly
Data-driven adjustments for combined use of NGA-East hard-rock ground motion and site amplification models
Model development in the Next Generation Attenuation-East (NGA-East) project included two components developed concurrently and independently: (1) earthquake ground-motion models (GMMs) that predict the median and aleatory variability of various intensity measures conditioned on magnitude and distance, derived for a reference hard-rock site condition with an average shear-wave velocity...
Authors
Maria E. Ramos-Sepulveda, Jonathan P. Stewart, Grace Alexandra Parker, Morgan P. Moschetti, Eric M. Thompson, Scott J. Brandenberg, Youssef M A Hashash, Ellen Rathje
The influence of anthropogenic regulation and evaporite dissolution on earthquake-triggered ground failure
Remote sensing observations of Searles Lake following the 2019 moment magnitude 7.1 Ridgecrest, California, earthquake reveal an area where surface ejecta is arranged in a repeating hexagonal pattern that is collocated with a solution-mining operation. By analyzing geologic and geotechnical data, here we show that the hexagonal surface ejecta is likely not a result of liquefaction...
Authors
Paula Madeline Burgi, Eric M. Thompson, Kate E. Allstadt, Kyle Dennis Murray, Henry (Ben) Mason, Sean Kamran Ahdi, Devin Katzenstein
Background seismic noise levels among the Caribbean network and the role of station proximity to coastline
The amplitude and frequency content of background seismic noise is highly variable with geographic location. Understanding the characteristics and behavior of background seismic noise as a function of location can inform approaches to improve network performance and in turn increase earthquake detection capabilities. Here, we calculate power spectral density estimates in one‐hour windows...
Authors
Justin T. Wilgus, Adam T. Ringler, Brandon Schmandt, David C. Wilson, Robert E. Anthony