Oct. 28, 2006 An earthquake swarm -- a steady drumbeat of
moderate, related seismic events -- over hours or days, often
can be observed near a volcano such as Mount St. Helens in
Washington state or in a geothermal region such as Yellowstone
National Park in Wyoming. New research led by a University of
Washington seismologist shows, however, that such swarms can
occur anywhere that is seismically active, not just near
volcanoes or geothermal regions. "In our research we saw swarms
everywhere and we could see the broad characteristics of how
they behaved," said John Vidale, a UW professor of Earth and
space sciences and director of the Pacific Northwest Seismograph
Network. Vidale and two colleagues, Katie Boyle of Lawrence
Livermore National Laboratory and Peter Shearer of the
University of California, San Diego, examined data from 83
Japanese earthquake swarms over about 2½ years. Their findings
confirmed work they published earlier this year that looked at
data from 72 events in southern California during a