Understanding intraplate earthquakes

China holds the record for the deadliest earthquake with 830,000 casualties, even though the event occurred far from a tectonic plate boundary.

In recent months, a U.S. team of geophysicists led by OU professor Randy Keller of the ConocoPhillips School of Geology and Geophysics completed two large seismic projects jointly with Chinese colleagues that will advance the understanding of the cause of devastating intraplate earthquakes. This effort complements that of Keller's Oklahoma Geological Survey colleagues, whose work focuses on the intraplate region around Oklahoma.

During the first experiment in China, the team deployed 500 seismic recorders along a profile extending from near Beijing to Mongolia. OU is collaborating with the Chinese Academy of Geological Sciences to produce an image of the velocity of the earth down to a depth of about 40 miles. The effort was part of China's ambitious SinoProbe project -- a comprehensive, five-year, eight-component geological and geophysical study of the lithosphere, the outer part of the Earth's surface.

In January, Keller and colleagues teamed with the Chinese Earthquake Administration and Chinese universities on the second experiment to deploy an array of seismographs in and around the city of Tangshan, which was destroyed by an earthquake in 1976. Tangshan sits on a fault, so the goal of this project is to establish new boundaries and determine earthquake hazards based on the new data. The team will use the data gathered to provide an image of the structure of the area to a depth of about 20 miles.

The seismic recorders employed on the project were instruments initially designed by Keller and others as part of a series of research grants. A $2M National Science Foundation grant to the University of Missouri and OU is providing some of the funding for Keller's team, however, the Chinese government funded most of the experiment costs in China. OU is continuing its collaboration with China by hosting a group of Chinese scientists and graduate students involved in processing, modeling and interpreting data collected during the two experiments.