The U.S. Geological Survey has released an updated version of its National Seismic Hazard Maps that predict decreased earthquake intensity for most of the United States except for two states.

The USGS said while most of the country saw a decrease in intensity estimates, intensity has increased for Oregon and Washington.

The map utilized the latest scientific information available to determine earthquake intensity. The increased intensity in western Oregon and Washington is due to new ground motion models for the offshore Cascadia subduction zone.

Models put the ground motion intensity in the Central and Eastern United States at about 10-to-25 percent lower. Ground motion estimates in most of California, Utah, Nevada, Arizona, Idaho and western Montana are as much as 30 percent lower for shaking that affects multistory buildings. For those six states, ground motion estimates remain unchanged for one- and two-story buildings.

Among some noteworthy items, the Wasatch fault in Utah was modeled to include a 7.4 earthquake. Offshore earthquakes were added as possible sources of earthquake for Charleston, S.C.

The maps are available at earthquake.usgs.gov/research/hazmaps/.

Last week the USGS, along with its partners, released a new earthquake rupture forecast for California--the first ever such forecast done statewide. That forecast focused on the likelihood of earthquakes happening on specific faults.

In an e-mail statement, Loretta Worters spokeswoman with the Insurance Information Institute said the revised map was well received by the insurance industry.

"This information obviously is useful from a mitigation standpoint as well as when determining a home's risk to earthquakes," she said.

(This story was updated at 4:35 p.m.)

Special Reports /

USGS Earthquake Map Increases Risk In Oregon, Wash.

Related Stories

Recommended For You