Publications

Currently, an aftershock sequence is ongoing in Alaska after the magnitude 7.0 Anchorage earthquake of November 30, 2018. Using two scenarios, determined with observations as of December 14, 2018, this report estimates that it will take between 2.5 years and 3 decades before the rate of aftershocks decays to the rate of earthquakes that were occurring in this area before the magnitude 7...

Wastewater disposal is generally accepted to be the primary cause of the increased seismicity rate in Oklahoma within the past decade, but no statewide analysis has investigated the contribution of hydraulic fracturing (HF) to the observed seismicity or the seismic hazard. Utilizing an enhanced seismicity catalog generated with multi‐station template matching from 2010‐2016 and all...

On 14 February 2017, two small (equivalent MD 0.8 and 1.0) seismic events occurred in proximity to the Oroville Dam in the Sierra Nevada foothills, California. To examine possible causal relationships between these events and reservoir operations, including the spillway failure starting prior to these events, we applied a new optimized template matching approach to seismic data between...

Before the digital era, seismograms were recorded in analog form and read manually by analysts. The digital era represents only about 25% of the total time span of instrumental seismology. Analog data provide important constraints on earthquake processes over the long term, and in some cases are the only data available. The media on which analog data are recorded degrades with time and...

Reasenberg and Jones (1989) introduced a statistical model for aftershock rate following a mainshock along with estimates of “generic” California parameter values based on past aftershock sequences. The Reasenberg and Jones (1989) model has been used for decades to issue aftershock forecasts following M≥5 mainshocks in California. Here, we update the “generic” parameters for California...

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No abstract available.

Enhanced reservoir connectivity generally requires maximizing the intersection between hydraulic fracture (HF) and preexisting underground natural fractures (NF), while having the hydraulic fracture continue to propagate across the natural fractures. Observations of downhole core samples suggest that these natural fractures are in fact veins filled with minerals such as calcite (Mighani...

The Cascadia Subduction Zone (CSZ) produces long-duration, large-magnitude earthquakes that could severely affect structures in the Pacific Northwest (PNW). The impact of synthetic M9.0 CSZ earthquakes on buildings in the Pacific Northwest is studied using eight reinforced concrete wall archetypes that range from 4 to 40 stories. These archetypes were subjected to an ensemble of...

We describe the data model that we intend to use in a publicly available site profile database under development for the United States. The initial implementation of the database contains data from California. Currently, our prototype data model consists of JavaScript Object Notation (JSON) format files for storing metadata and data. For a site to be included in the database, the minimum...

An exposure of a creeping segment of the Bartlett Springs Fault (BSF), part of the San Andreas Fault system in northern California, is a ~1.5‐m‐wide zone of serpentinite‐bearing fault gouge cutting through Late Pleistocene fluvial deposits. The fault gouge consists of porphyroclasts of antigorite serpentinite, talc, chlorite, and tremolite‐actinolite, along with some Franciscan...

A total of seven independent ML ≥ 4.0 earthquakes occurred in the Los Angeles, California, basin, during the early instrumental period between 1932 and 1952, the largest of which was the 1933 Long Beach earthquake. Revising available macroseismic and instrumental data for a total of 6 4.0 ≤ ML ≤ 5.1 events between 1938 and 1944, we conclude that early instrumental locations can be...