Wallace L. Ulrich

Acting Director & State Geologist
Wyoming State Geological Survey
P.O. Box 1347
Laramie, WY 82073


MEDIA ADVISORY
Wyoming State Geological Survey

Earthquake felt Aug. 4 in western Wyoming

A light earthquake occurred Aug. 4 in eastern Teton County and was felt in much of western Wyoming and portions of eastern Idaho. There were no immediate reports of injuries or damage.

The earthquake, which occurred at 6:04 p.m., was felt in Teton, Park, Sweetwater, Sublette, and Lincoln counties, according to information received by the Wyoming State Geological Survey (WSGS).

The event was approximately 20 miles east-northeast of Jackson and 40 miles west of Dubois.

The magnitude 4.8, intensity IV earthquake occurred 3.1 miles below the surface, according to the U.S. Geological Survey’s National Earthquake Information Center (NEIC) in Golden, Colo.

The earthquake was reportedly felt as intensity IV in Kelly and Moose and intensity III in Dubois, Jackson, Moran and Alta. During an intensity IV event, hanging objects swing, vehicles that are not moving rock, vibrations are felt similar to that of a passing truck, windows and dishes rattle and glasses clink.

It was felt as intensity II in Yellowstone National Park, Cody, Lander, Rock Springs, Bondurant, Cora, Green River, Daniel and Thayne.

The strength of an earthquake at its epicenter is called its magnitude, as measured on the Richter scale. Light earthquakes – those between magnitude 4.0 and 4.9 – can but do not usually 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. These reports provide historic seismicity and information about long- and short-term seismic hazard analysis.