Top Expert Warns San Andreas Fault Is 'Locked, Loaded and Ready to Roll' — Here's What It Means If He’s Right

A leading earthquake expert is warning that Southern California’s section of the San Andreas fault is “locked, loaded and ready to roll,” setting off fears of an impending deadly disaster.

Thomas Jordan, director of the Southern California Earthquake Center, explained during his keynote speech Wednesday at the National Earthquake Conference that the “springs on the San Andreas system have been wound very, very tight.” It’s been nearly 160 years since the last big earthquake hit southern San Andreas, a 7.9-magnitude event in 1857.

“The southern San Andreas fault, in particular, looks like it’s locked, loaded and ready to go,” he said, adding that other parts of the fault are also overdue for activity.

The Los Angeles Times breaks down why this is so concerning:

Other sections of the San Andreas fault also are far overdue for a big quake. Further southeast of the Cajon Pass, such as in San Bernardino County, the fault has not moved substantially since an earthquake in 1812, and further southeast toward the Salton Sea, it has been relatively quiet since about 1680 to 1690.

Here’s the problem: Scientists have observed that based on the movement of tectonic plates, with the Pacific plate moving northwest of the North American plate, earthquakes should be relieving about 16 feet of accumulated plate movement every 100 years. Yet the San Andreas has not relieved stress that has been building up for more than a century.

So, how devastating would a major earthquake on the southern San Andreas fault similar to the one that occurred in 1857 actually be?

In 2008, a U.S. Geological Survey concluded that a 7.8-magnitude earthquake on the southern part of the fault would leave roughly 1,800 people dead, 50,000 injured and cities with $200 billion in damages. The report also estimated such a catastrophe could leave areas without a sewer system for up to six months.

Jordan advised California cities to start preparing now for an earthquake as large as magnitude 8.

Watch a simulation of a magnitude 8 earthquake hitting the San Andreas fault:

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