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 20, 2010|
Four additional earthquakes felt in Yellowstone
Four additional minor earthquakes were felt Jan. 19 in Yellowstone National Park, just a day after two minor earthquakes were felt there. There were no reports of injuries or damage.
The six earthquakes were associated with a small earthquake swarm that continued through 7 a.m. Jan. 20, 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 do not normally indicate that large, damaging earthquakes are imminent.
The first earthquake that was felt Jan. 19 in Yellowstone occurred at 9:48 a.m. approximately 10 miles southeast of West Yellowstone, Mont., and 19 miles east-northeast of Island Park, Idaho.
The magnitude 3.3, intensity II earthquake occurred 4.2 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 3.5 event, occurred at 2:32 p.m. and was felt in Yellowstone National Park as intensity II. The earthquake occurred 10 miles southeast of West Yellowstone and 18 miles east-northeast of Island Park at a depth of 5.8 miles.
A third earthquake happened at 6:35 p.m. and was felt as intensity II in Yellowstone. The 3.1 magnitude earthquake occurred 9 miles southeast of West Yellowstone and 18 miles east-northeast of Island Park at a depth of 5.8 miles.
A fourth earthquake, magnitude 3.4, took place at 9:41 p.m. The event occurred 9 miles southeast of West Yellowstone and 19 miles east-northeast of Island Park at a depth of 5.4 miles. The earthquake was felt as intensity II in Yellowstone.
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.