The Uniform Building Code (UBC) - see the International Conference of Building Officials - classifies earthquake hazard on a scale from 0 (least hazard) to 4 (most hazard). These values are used to determine the strengths of various components of a building required to resist earthquake damage. The current version of the UBC map reflects the hazard from great earthquakes on the Cascadia fault that lies offshore of northern California, Oregon, Washington, and British Columbia.

How UBC seismic zone maps have changed with time
in the Pacific Northwest