How common are faults in California?
There are hundreds of identified faults in California; about 200 are considered potentially hazardous based on their slip rates in recent geological time (the last 10,000 years). More than 70 percent of the state’s population resides within 30 miles of a fault where high ground shaking could occur in the next 50 years. Does California have more and bigger earthquakes than anyplace else? Actually, Alaska has more earthquakes and the biggest ones in the U.S. The largest earthquake in history occurred in Chile (a magnitude 9.5 on May 22, 1960). The biggest earthquake in the contiguous 48 states was the magnitude 7.9 Ft. Tejon quake on Jan. 9, 1857. What is an epicenter? Earthquake ruptures usually begin far under the surface of the Earth. The point of origin miles down is called the hypocenter. The epicenter is the point on the surface directly above the hypocenter. How often do earthquakes happen? The National Earthquake Information Center (U.S.) reports 12,000-14,000 earthquakes a year
