The mission of this page is to provide an education for the public of the earthquake hazards and potential within and around the State of Idaho. By educating our citizens, we can begin mitigating or reducing in advance the effect of this most unpredictable natural hazard.
Idaho has experienced two of the largest earthquakes in the contiguous United States in the last forty years, the 1959 Hebgen Lake Earthquake (7.5M), and the 1983 Borah Peak Earthquake (7.3M).
All of Idaho's 44 counties have moderate or higher risk. At least 38 counties need special focus on earthquake preparedness as they are in areas of high to severe risk. Estimates place nearly 80% of our population is concentrated in high seismic risk areas. Geography has also concentrated lifelines (utilities and transportation routes) and critical facilities (dams, government, military and research installations) in a few corridors. A number of the areas are near range front faults like Boise. Other cases are in large resort areas and tourist attractions in seismically active mountainous areas like Sun Valley and Yellowstone.
This active seismic belt extends in an east-west direction across the center of the state where we have little geologic understanding of its characteristics.
Recent geological investigations along the Snake River near Brownlee Reservoir (there are three large reservoir projects in this vicinity) have demonstrated the existence of clustered seismicity that may be related to mapped faults. Seismic activity also appears to be related to the Osburn Fault, a large feature along a major structural system called the Lewis and Clark Line (Wallace Mullen area). A number of other clusters of historic seismicity are also apparent in the state (Breckenridge and others, 1984; Stover and others, 1986).
Digital Map of Idaho (Earthquakes): http://imnh.isu.edu/digitalatlas/geo/quakes/quakes.htm
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Bureau of Homeland Security
4040 Guard Street
Building 600
Boise, Idaho 83705
(208) 334-3460