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Swarm at Yellowstone Has Diminished

USGS Volcano Hazards Program Volcano Update

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YVO update page and observatory web site

The January-February, 2010, earthquake swarm at Yellowstone National Park has diminished in terms of earthquake-occurrence rate and magnitudes. A few small events continue to be recorded each day at the University of Utah Seismograph Stations (UUSS), the YVO partner responsible for earthquake monitoring at Yellowstone National Park. Seismologists cannot state that the swarm has ceased, but the rate of earthquake occurrence in the Madison Plateau area is now at background levels for this area of Yellowstone. As such, UUSS and YVO will cease to issue daily updates unless conditions change.

As of February 8, 2010 14:00 MST, there have been 1799 events recorded by the automatic earthquake system of the University of Utah. Of those, 827 have been verified by seismic analysts and forwarded to the National Earthquake Information Center (NEIC) for incorporation in the permanent listing of earthquakes. Seismologists of the University of Utah will continue to analyze data from the past several weeks to finalize the earthquake information.

The largest events were a pair of earthquakes of magnitude 3.7 and 3.8 that occurred after 11 PM MST on January 20, 2010. Both events were felt throughout the park and in surrounding communities in Wyoming, Montana, and Idaho. Other smaller events were also reported as felt.

The earthquakes were on the Madison Plateau along the northwest side of the Yellowstone caldera, in an area where previous swarms had occurred over the past 30 years. Visual observation of landforms and geothermal features by Yellowstone National Park personnel did not show any changes that could be attributed to the earthquakes.

Yellowstone National Park is in a region of active seismicity associated with regional Basin and Range extension of the Western U.S., as well as youthful volcanism of the Yellowstone volcanic field. Pressurization due to crustal magma bodies of the Yellowstone hotspot and associated shallow geothermal reservoirs can also contribute to earthquakes. Scientists will continue to research the origin of these and other Yellowstone earthquakes.

Any new information will be posted to: http://volcanoes.usgs.gov/yvo/activity/index.php

A summary of the swarm and links to additional information can be found at: http://volcanoes.usgs.gov/yvo/publications/2010/10swarm.php

Seismic information on the earthquake can be viewed at the University of Utah Seismograph Stations: http://www.seis.utah.edu/

Seismograph recordings from stations of the Yellowstone seismograph network can be viewed online at: http://quake.utah.edu/helicorder/yell_webi.htm

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