Publications
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Induced seismicity reduces seismic hazard?
Earthquakes caused by human activities have been observed for decades. Often these are related to industrial activities pumping fluids into deep geologic formations, like with wastewater disposal. The simplest theory connecting these processes to earthquakes is straightforward: injection leads to fluid pressure changes that either reduce the strength of preexisting faults or generate new faults. I
Authors
Andrew J. Barbour, Fred Pollitz
The current unlikely earthquake hiatus at California’s transform boundary paleoseismic sites
Paleoseismic and historical earthquake records used to quantify earthquake recurrence rates can also be used to test the likelihood of seismically quiescent periods. At principal paleoseismic sites in California on the San Andreas, San Jacinto, Elsinore, and Hayward faults, no ground‐rupturing earthquake has occurred in the last 100 yr, yet this interval is about three times the average interearth
Authors
Glenn Biasi, Katherine Scharer
Improving earthquake forecasts during swarms with a duration model
Earthquake swarms present a challenge for operational earthquake forecasting because they are driven primarily by transient external processes, such as fluid flow, the behavior and duration of which are difficult to predict. In this study, we develop a swarm duration model to estimate how long a swarm is likely to last based on actuarial statistics of previous swarms in a given region. We demonstr
Authors
Andrea L. Llenos, Nicholas van der Elst
Sea level rise in the Samoan Islands escalated by viscoelastic relaxation after the 2009 Samoa‐Tonga earthquake
The Samoan islands are an archipelago hosting a quarter million people mostly residing in three major islands, Savai'i and Upolu (Samoa), and Tutuila (American Samoa). The islands have experienced sea level rise by 2–3 mm/year during the last half century. The rate, however, has dramatically increased following the Mw 8.1 Samoa‐Tonga earthquake doublet (megathrust + normal faulting) in September 2
Authors
Shin-Chan Han, Jeanne Sauber, Fred Pollitz, Richard Ray
Slow-growing and extended-duration seismicity swarms: Reactivating joints or foliations in the Cahuilla Valley Pluton, Central Peninsular Ranges, Southern California
Three prolific earthquake swarms and numerous smaller ones have occurred since 1980 in the Mesozoic igneous plutonic rocks of the Perris block of the Peninsular Ranges, Southern California. The major swarms occurred in 1980–1981, 1983–1984, and 2016–2018, with the latest swarm still ongoing. These swarms have no clear mainshock, with the largest events of ML 3.6, ML 3.7, and Mw 4.4. Each successiv
Authors
E. Hauksson, Z. Ross, Elizabeth S. Cochran
Quantitative coseismic and precipitation-induced landslide risk mapping for the country of Lebanon
Quantitative landslide risk assessment is a key step in creating appropriate land use policies. The forced migration of those displaced by recent events in Syria has highlighted the need for studies to guide humanitarian aid and resettlement policies. In 2011, armed conflict in the region precipitated the largest refugee crisis in a generation. Over 1.5 million displaced Syrians now reside in Leba
Authors
William Pollock, Joseph Wartman, Grace Abou-Jaoude, Alex R. R. Grant
Characteristics and spatial variability of wind noise on near-surface broadband seismometers
By coupling with the ground, wind causes ground motion that appears on seismic records as noise across a wide bandwidth. This wind-generated noise can drown out important features such as small earthquakes and prevent observation of normal modes from large earthquakes. Because the wind field is heterogeneous at local scales due to structures, diurnal heating, and topography, wind-induced seismic n
Authors
S. N. Dybing, Adam T. Ringler, David C. Wilson, Robert E. Anthony
Delayed dynamic triggering of disposal-induced earthquakes observed by a dense array in Northern Oklahoma
Recent increases in earthquake occurrence rates in Oklahoma have been linked to the injection of large volumes of saltwater, a byproduct of oil and gas extraction. Here we present a detailed study of remote earthquake triggering in an area of active injection‐induced seismicity in northern Oklahoma using data from the LArge‐n Seismic Survey in Oklahoma (LASSO) temporary array and nearby permanent
Authors
A. Pena Castro, Sara L. Dougherty, R. M. Harrington, Elizabeth S. Cochran
Leakage and increasing fluid pressure detected in Oklahoma's wastewater disposal reservoir
The Arbuckle Group is the principal reservoir used for wastewater disposal in Oklahoma. In Osage County—a seismically quiet part of the state—continuous measurements of fluid pressure reveal that pressure in the reservoir is increasing by at least 5 kPa annually and sometimes at a much higher rate. Tidal analysis reveals that fluid level changes lead the local strain tides, with no apparent influe
Authors
Andrew Barbour, Lian Xue, Evelyn Roeloffs, Justin Rubinstein
Earthquake stress drop and Arias Intensity
We determine earthquake stress drops directly from the Arias intensity database of NGA-West2. Arias intensity (Arias, 1970) is an engineering measure proportional to the integral of the absolute value of acceleration squared, over the significant duration of the signal. As such, it is closely related to root-mean-square acceleration, and can readily be connected to earthquake stress drop (Hanks an
Authors
Annemarie S. Baltay, Thomas C. Hanks, Norman A. Abrahamson
The Mw 6.0 South Napa earthquake of August 24, 2014—Observations of surface faulting and ground deformation, with recommendations for improving post-earthquake field investigations
The Mw 6.0 South Napa earthquake of August 24, 2014, produced complex and extensive surface faulting and other ground deformation features. Following the event, geologists made more than 1,200 field observations at locations where tectonic faulting and ground failure produced visible deformation that fractured and disturbed the ground surface. At a few locations, large-scale, detailed, field-based
Authors
Daniel J. Ponti, Carla M. Rosa, James Luke Blair
Seismic hazard assessment at the Fallon, Nevada, Frontier Observatory for Research in Geothermal Energy site
Enhanced geothermal systems (EGS) technology aims to engineer a productive geothermal reservoir in regions of hot, but low permeability, rocks. In any EGS operation, the rock mass requires stimulation by high pressure injection of fluids, which has the potential to induce seismicity. To address the seismic hazard specifically, a probabilistic seismic hazard assessment (PSHA) is often required and
Authors
J. Ole Kaven, Ernest L. Majer, William Foxall, Eric L. Sonnenthal, William Pettitt