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Shake it off? Half of Americans at risk for earthquakes

Doyle Rice
USA TODAY
Pedestrians stop to examine a crumbling facade at the Vintner's Collective tasting room in Napa, Calif., after an earthquake  Aug. 24, 2014.

Nearly half of the U.S. population lives in an area prone to earthquakes, according to the U.S. Geological Survey.

More than 143 million Americans in the 48 contiguous states are at risk of potential damage from the ground shaking, according to a USGS report released Wednesday. That is twice as many people as in a 1994 estimate from the Federal Emergency Management Agency.

"Significantly more Americans are exposed to earthquake shaking, reflecting both the movement of the population to higher risk areas on the West Coast and a change in hazard assessments," said Bill Leith, a co-author of the report and a senior science adviser at the geological survey.

About 28 million Americans are in danger of experiencing "strong shaking during their lifetime," the report said. More than 6,000 fire stations, 800 hospitals and nearly 20,000 public and private schools are at risk of strong ground motion from earthquakes that could severely damage the structures and cause deaths.

Earthquakes cause an average of $4.5 billion in damages per year, the USGS report said. Most financial losses occur in California, Oregon and Washington.

The report was one of three out this week regarding earthquakes in the USA. The other two dealt with an increase in man-made earthquakes from the process of extracting oil and gas from underground sources, known as "hydraulic fracturing" or fracking.

Another USGS report released Thursday found that more than a dozen areas in the USA in recent years have had small earthquakes triggered by the fracking process. Scientists pinpointed eight states with increased rates of man-made quakes: Alabama, Arkansas, Colorado, Kansas, New Mexico, Ohio, Oklahoma and Texas.

"These earthquakes are occurring at a higher rate than ever before and pose a much greater risk to people living nearby," said Mark Petersen, who heads the USGS national mapping project.

The USGS said the fracking itself doesn't cause quakes, but the resulting wastewater disposal associated with fracking may be the trigger. The wastewater disposal increases pressure underground, which may lubricate nearby faults and make earthquakes more likely to occur, the USGS said.

The findings were released in Pasadena, Calif., at a meeting of the Seismological Society of America.

Another study, published Tuesday in the journal Nature Communications, pinpointed a region west of Fort Worth hit with a swarm of small earthquakes in 2013 and 2014, probably because of the fracking process.

The outlined areas show where man-made earthquakes have occurred since 2009.
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