Eastern U.S. earthquakes pack strong punch - study

Reuters News
Posted: Nov 06, 2012 3:07 PM
Eastern U.S. earthquakes pack strong punch - study

WASHINGTON (Reuters) - Shock waves from earthquakes in the eastern United States can travel much farther and cause damage over larger areas than previously thought, the U.S. Geological Survey said on Tuesday in a study of the strong quake that hit Virginia last year.

The 5.8 magnitude quake triggered landslides at distances four times farther - and over an area 20 times larger - than previous research showed, the USGS said in a statement.

The study offers more evidence that although the East Coast has fewer quakes than the West Coast, the damage can be more extensive.

"We used landslides as an example and direct physical evidence to see how far-reaching shaking from East Coast earthquakes could be," said Randall Jibson, USGS scientist and lead author of the study.

The USGS found that the farthest landslide from the Virginia earthquake was 150 miles from the epicenter, by far the greatest landslide distance recorded from any quake of similar magnitude.

It is estimated that about one-third of the U.S. population could have felt the earthquake, the most for any quake in U.S. history.

Landslides enclosed an area of about 12,900 square miles (33,400 square km). Previous studies indicated an expected area of about 580 square miles (1,500 square km) from an earthquake of similar strength.

The difference between shaking in the eastern United States versus the west is due in part to the geologic structure and rock properties that allow seismic waves to travel farther without weakening, the USGS said.

The study will help with earthquake hazard and risk assessments and emergency preparedness. It also will aid in checking the geological record for signs of quakes from the Virginia seismic zone.

The research was presented on Tuesday at the Geological Society of America conference. It will be published in the December issue of the Bulletin of the Seismological Society of America.

(Reporting by Ian Simpson; Editing by Xavier Briand)