EARTHQUAKE HAZARDS

Virginia and much of the East Coast experienced a widely-felt earthquake at 1:51 p.m. eastern daylight time on Tuesday, August 23, 2011. According to the U.S. Geological Survey, the epicenter of the quake was located near Cuckoo, in Louisa County. With a magnitude of 5.8, this is the largest Virginia earthquake recorded by seismometers. More than 80 aftershocks have been reported by the USGS and the area is currently being monitored by geophysicists from several leading science institutions.

The U.S. Geological Survey is now reporting that this is the most widely-felt earthquake in U.S. history. Photos from the hazard assessment team can be found here.

Earthquakes in the eastern U.S. are different from the earthquakes that occur in more seismically active areas, such as California. California is located on the boundary between two large blocks of the earth’s crust, the North American and Pacific tectonic plates. As these plates grind past each other, stresses build up and periodically release catastrophically. Virginia, however, is located in the middle of the North American plate; the nearest tectonic plate boundary is the Mid-Atlantic Ridge, in the middle of the Atlantic Ocean. Earthquake activity occurring away from plate boundaries is known as “intraplate seismicity.” Such earthquakes are generally less severe and less damaging than those occurring at plate boundaries, although occasional large earthquakes, such as the 5.8M in central Virginia, do occur.*

Virginia DEM Earthquake Page
https://www.vaemergency.gov/earthquakes-landslides/

Virginia Tech Seismological Observatory
http://www.magma.geos.vt.edu/vtso/

USGS Virginia Earthquake Webpage
https://earthquake.usgs.gov/earthquakes/byregion/virginia.php

*Earthquake hazard information from the Virginia Dept. of Mines, Minerals, and Energy webpage:
https://www.dmme.virginia.gov/DGMR/earthquake2011.shtml