Publications

The scaling of rupture properties with magnitude is of critical importance to earthquake early warning (EEW) systems that rely on source characterization using limited snapshots of waveform data. ShakeAlert, a prototype EEW system that is being developed for the western United States, provides real-time estimates of earthquake magnitude based on P-wave peak ground displacements measured...

Nonearthquake seismic events from sources such as landslides, debris flows, dam collapses, floods, glaciers, and avalanches are rarely included in traditional earthquake catalogs. The new Incorporated Research Institutions for Seismology (IRIS) Data Management Center Exotic Seismic Events Catalog data product provides information on such events to help accelerate research in the area of

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...

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

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...

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...

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

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...

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...

An important predictive variable for site amplification is the site dominant frequency (⁠ƒd⁠). At seismic monitoring stations, ƒd can be calculated from the peak of the horizontal‐to‐vertical spectral ratios (HVSRs) obtained from earthquake recordings (eHVSR). For other sites, ƒd can be estimated from microseismic (mHVSR) observations. We compare the ƒd values derived from eHVSR (5%...

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...

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...