Programs and Services
Geologic Hazards—Earthquakes
Geological and seismological studies show that earthquakes are likely
to happen in any of several active zones in Idaho and adjacent states.
Idaho is ranked fifth highest in the nation for earthquake hazard. Only
California, Nevada, Utah, and Alaska have a greater overall hazard. Idaho
has experienced the two largest earthquakes in the contiguous United
States in the last thirty years—the 1959 Hebgen Lake earthquake (M7.5) and
the 1983 Borah Peak earthquake (M7.3). Both tremors caused fatalities and
millions of dollars in damage.
In all parts of Idaho, the historical record of
seismicity reveals at least a moderate threat from earthquakes. The Idaho
Geological Survey addresses earthquake concerns by studying faults and
seismic activity, and by promoting earthquake education
programs. The Survey works closely with other agencies in planning state
and regional earthquake policy and response, and participates in regional
organizations such as the Western States Seismic Policy Council (WSSPC).
