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 The findings come from updated earthquake hazard maps that were
released by the U.S. Geological Survey on Thursday. The maps are
used to help define safe building codes, help emergency responders
plan after a quake, and influence insurance rates, the report said.
"The cost of inaction in planning for future earthquakes and other
natural disasters can be very high, as demonstrated by several
recent damaging events across the globe," Mark Petersen, chief of
the USGS National Seismic Hazard Mapping Project, said in a
statement.
The western United States faces a high risk of damaging earthquakes
up and down the coast and in the intermountain region, the report
said. The California cities of San Jose, Vallejo and San Diego all
saw a heightened threat, as new fault lines have been recently
discovered, the report said.
The cities of Irvine, Santa Barbara and Oakland had their threats
downgraded however, the report said.
It also upgraded the risks facing parts of the central and eastern
United States, singling out areas near New Madrid, Missouri, and
Charleston, South Carolina. Scientists did however lower the threat
facing New York City's skyscrapers, as slow-shaking quakes which
impact taller buildings are less likely in the area than previously
thought.
The 16 states with areas facing the highest risk are Alaska,
Arkansas, California, Hawaii, Idaho, Illinois, Kentucky, Missouri,
Montana, Nevada, Oregon, South Carolina, Tennessee, Utah,
Washington, and Wyoming.
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The survey noted a sharp spike in the number of earthquakes over
magnitude 3, potentially driven by hydraulic fracturing in states
like Texas, Oklahoma and Arkansas. Between 2010 and 2012 more than
300 quakes were recorded, compared to an average of just 21 per year
over recent decades in the region.
While those quakes were not included in the analysis of earthquake
risk, researchers said that planners should consider higher
potential for shaking given the increased seismic activity.
The maps are based on over a century of observed earthquake data.
The last assessments were published in 2008 and were updated to
account for new scientific modeling and studies on quakes, the
report said. (Reporting by Curtis Skinner in New York; Editing by
Eric Beech)
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