Ronald C. Surdam
Wyoming State Geological Survey
P.O. Box 1347
Laramie, WY 82073
Editor in Chief
307-766-2286, ext. 255
|News Release||January 21, 2010|
Three additional earthquakes felt in Yellowstone
Three minor earthquakes were felt Jan. 20 in Yellowstone National Park, and there were no reports of injuries or damage. They were a continuation of the earthquake swarm that started Jan. 17.
The events brought the total number of earthquakes felt to nine, and the seismic activity was ongoing as of 7 a.m. Jan. 21, according to information received by the Wyoming State Geological Survey (WSGS).
An earthquake swarm is a collection of small earthquakes that happen in the same general area and time. Earthquake swarms in Yellowstone are not usually indicative that large, damaging earthquakes are imminent.
The first earthquake that was felt Jan. 20 occurred at 2:43 p.m. approximately 9 miles southeast of West Yellowstone, Mont., and 19 miles east-northeast of Island Park, Idaho.
The magnitude 2.9, intensity II earthquake occurred 5.8 miles below the surface, according to the U.S. Geological Survey’s National Earthquake Information Center (NEIC) in Golden, Colo.
The second earthquake, a magnitude 3.6 event, occurred at 11:01 p.m. and was felt as intensity III. The earthquake occurred 9 miles southeast of West Yellowstone and 18 miles east-northeast of Island Park at a depth of 6 miles.
A third event happened at 11:16 p.m. and was felt as intensity III. The 3.7 magnitude earthquake occurred 9 miles southeast of West Yellowstone and 19 miles east-northeast of Island Park at a depth of 6.4 miles.
The strength of an earthquake at its epicenter is called its magnitude, as measured on the Richter scale. Minor earthquakes – those between magnitude 3 and 3.9 – do not cause structural damage.
The effect of an earthquake on the surface is called its intensity, as measured on the Modified Mercalli Intensity Scale. Intensities range from I (imperceptible shaking) to XII (catastrophic destruction).
The WSGS has compiled seismological characterizations of all Wyoming counties, which include analyses of historic seismicity. See Earthquake Database for more information, or contact Seth Wittke at 307-766-2286, ext. 244, or by e-mail at firstname.lastname@example.org.