Scientists have recently discovered an active fault underneath Los Angeles that may have been the cause of four previous large-magnitude earthquakes. The fault, named the Puente Hills Blind Thrust System, is 2 to 11 miles deep and extends for almost 31 miles from northern Orange County, through Los Angeles, and up to Beverly Hills. James Dolan, a professor at The University of Southern California’s Department of Earth Sciences, had this to say about the newfound fault: “In terms of location, it couldn’t be much worse. Downtown L.A. is sitting on top of this thing.” A blind thrust fault is one that does not reach the earth’s surface, and as such has remained, until recently, a point of argument even over its existence among those who study the earth’s faults and the ensuing earthquakes.

Scientists believe that the Puente Hills fault once caused an earthquake measuring 7.5 on the Richter scale—15 times stronger than the 1994 earthquake that hit north of Los Angeles, killing 51 people. Dolan went on to say, “The good news is that major earthquakes along this fault are very infrequent, it may not happen again for thousands of years. The bad news is that it could be very strong when it does happen.”

Source: The National Geographic