5-year UC Riverside-led research project funded by $4.6 million National Science Foundation grant

Geophysicists at the University of California, Riverside have received a $4.6 million grant from the National Science Foundation to study the dynamics of earthquake fault systems. Such systems occur where the world's tectonic plates meet, and control the occurrence and characteristics of the earthquakes they generate.

The UC Riverside-led team will develop and use large-scale supercomputer simulations to investigate these systems, and will focus first on the North American plate boundary and the San Andreas fault system of Northern and Southern California. The simulations can be performed, however, for any earthquake-prone region on Earth.

"Observations of earthquakes go back to only about 100 years, resulting in a relatively short record," said James Dieterich, a distinguished professor of geophysics in the Department of Earth Sciences and the five-year grant's principal investigator. "If we get the physics right, our simulations of plate boundary fault systems – at 1-kilometer resolution for California – will span more than 10,000 years of plate motion and consist of up to a million discrete earthquake events, giving us abundant data to analyze."

Dieterich, a member of the National Academy of Sciences, explained that his simulations will provide the means to integrate a wide range of observations from seismology and earthquake geology into a common framework. In particular, the fault system models will integrate advanced ground motion simulations to better characterize the magnitude and variability of ground shaking in damaging earthquakes.

"A computer model of the kind we are developing is an excellent experimental tool for understanding how fault systems organize themselves, how earthquake stresses build up in the Earth," he said. "The simulations will help us better understand the interactions that give rise to observable effects. They are computationally fast and efficient, and one of the project goals is to improve our short- and long-term earthquake forecasting capabilities. More accurate forecasting has practical advantages – earthquake insurance, for example, relies heavily on forecasts. More important, better forecasting can save more lives."

Dieterich and colleagues also will study in detail the long-term processes that condition fault systems to fail in great earthquakes (larger than 8 on the Richter scale). An increasing fraction of the world's population lives in regions where great earthquakes occur – or could occur – and is exposed to high seismic risk as a result. Great earthquakes, such as the 1906 earthquake in San Francisco and the one off the coast of Japan earlier this year, occur every 300-500 years.

Dieterich is an internationally renowned authority in rock mechanics, seismology and volcanology. His research has led to a new understanding of the Earth's crust. He is the recipient on numerous awards including the Bucher Medal from the American Geophysical Union; and the Distinguished Service Award from the US Department of Interior. He is a fellow of the American Geophysical Union.

He will be joined in the research project by researchers at UCR, Brown University, Columbia University, the University of Southern California, San Diego State University, UC San Diego and the US Geological Survey. The UCR researchers are David Oglesby, an associate professor of geophysics; Elizabeth Cochran, an assistant adjunct professor; Keith Richards-Dinger, an assistant researcher; and graduate students.

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