Major Earthquake Could Be Overdue on San Andreas Fault North of L.A., New USGS Study Finds

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

An aerial view of the San Andreas fault in the Carrizo Plain, Central California. (Credit: USGS)

The research found earthquakes happen there on average every 100 years. The last major temblor occurred 160 years ago, a catastrophic geological event that ruptured an astonishing 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.

“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.

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These images show the location where scientists studied a section of the San Andreas fault, identified by the red line, and found that earthquakes there happened on average once every 100 years. The most common earthquake found was magnitude 7.5. (Credit: USGS via Los Angeles Times)