The Wasatch Fault runs about 380 kilometres along the western foot of the Wasatch Range in Utah, passing directly beside Salt Lake City, Provo and Ogden. It forms the sharp boundary between the mountains and the valleys of the Basin and Range province, a region stretched by crustal extension.
It is a normal fault, meaning the valley block drops down relative to the rising mountains as the crust pulls apart; its towering fault scarps are classic evidence of repeated prehistoric ruptures. Geologists divide it into segments, several of which are capable of producing earthquakes around magnitude 7.
Although no large earthquake has struck the fault in the historical record, paleoseismic trenching shows major events every few hundred to a couple of thousand years, with the last on some central segments centuries ago. Because Utah's population is concentrated right along the fault, it is regarded as one of the most serious seismic hazards in the western United States.