USGS study: Southern California overdue for major earthquake

Posted at 8:55 AM, Mar 07, 2017
and last updated 2017-03-07 14:55:00-05

LOS ANGELES - Southern California could be overdue for a major earthquake along the Grapevine north of Los Angeles, according to a new study by the U.S. Geological Survey.

The research found earthquakes happen there on average every 100 years, the Los Angeles Times reported. The last major temblor occurred 160 years ago, rupturing 185 miles of the San Andreas fault.

The land on either side of the fault has been pushing against the other at a rate of more than 1 inch a year since 1857, the researchers said, accumulating energy that will be suddenly released in a major earthquake, when the land along the fault would move by many feet, The Times reported.

"So you expect that amount of accumulation of energy will be released in the future in a large-magnitude rupture, somewhere along the San Andreas," said the lead author of the study, USGS research geologist Kate Scharer, according to The Times.

A repeat of the 1857 earthquake could damage aqueducts that ferry water into Southern California from the north, disrupt electric transmission lines and tear up Interstate 5, whose Grapevine section runs on top of the San Andreas fault at Tejon Pass, The Times reported.

Central Los Angeles could experience a couple of minutes of shaking, which could feel like a lifetime compared with the 1994 Northridge earthquake, which shook for roughly 15 seconds.

"This would be more broadly felt across the basin," Scharer said, according to The Times. "It would impact our ability to be a world-class city."

Scientists observing trenches at this site discovered that earthquakes on this section of the San Andreas fault occurred on average once every 100 years, according to The Times.