Stories a Trench Can Tell—Determining St. George Earthquake Threat

Geologists are digging into the Washington fault about three miles south of the Utah-Arizona border in Arizona. “The fault is three miles east of St. George and runs through the nearby city of Washington,” said Bill Lund, UGS senior geologist. “There is evidence of surface rupturing earthquakes. Our goal is to figure out how often the fault has moved and how large the earthquakes have been. That will help us understand the potential for future earthquake activity.”