Programs and Services
Earthquake Risk in Idaho
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 risk.
The 1991 Uniform Building Code (UBC), a nationwide industry standard, sets construction
standards for different seismic zones in the nation. UBC seismic zone rankings for Idaho
are among the highest in the nation. When buildings are built to these standards they have
a better chance to withstand earthquakes.
Studies of ground shaking in Idaho during previous earthquakes has led to better
interpretations of the seismic threat to buildings. In areas of severe seismic shaking
hazard, older buildings are especially vulnerable to damage. Older buildings are at risk
even if their foundations are on solid bedrock. Areas shown on the map with high seismic
shaking hazard can experience earthquakes with intensity VII where weaker soils exist.
Most populated areas in Idaho are located on or near alluvial deposits which provide
poorer building site conditions during earthquakes. Older buildings may suffer damage even
in areas of moderate ground shaking hazards.
Seismic Shaking Hazard of Idaho