Now Playing

Science: We're Due for a Swarm of Earthquakes in 3... 2... 1...

A "cluster of large earthquakes" could be heading our way. 

The aftermath of the 1989 Loma Prieta earthquake. 

What Godzilla couldn't accomplish, Mother Nature might. According to scientists, San Francisco is due for a cluster of large earthquakes soon.

Well, soon in geological time, which means sometime in the next few decades. But still, it's not good news.

The study, published in the Bulletin of the Seismological Society of America argues that earthquakes happen in cyclical frequency—sometimes many and sometimes a few. Despite the 1989 quake, we are still headed on the up slope of that sinusoid. The scientists reached the conclusion by studying historical records dating back to 1776 and physical evidence including radiation dating and the movement of layers of rocks at fault lines dating back to 1600. They found a cluster of earthquakes dating from 1690 to 1776, followed by a period of relative quiet that lasted until 1906. 

The cause that they identified was no different from what your yoga instructor keeps telling you during those savasana lectures you tune out: Stress builds up. In case, it's stress along geological plates grinding into each other. Then, during earthquakes, it "is released and builds up again,” said David Schwartz, a geologist with the US Geological Survey who led the study. Currently, the highest levels of stress—and hence the greatest risk for quakes—is along faultlines near Fremont and Hayward, as well as along the Peninsula from San Mateo to Palo Alto.

"Everyone is still thinking about a repeat of the 1906 quake," Schwartz told the Wall Street Journal. "But what happens if every five years we get a magnitude 6.8 or 7.2? That's not outside the realm of possibility."

As SFist reminded us, "[Now] is a good time for yet another nudging reminder that you should be pulling an earthquake kit together, if you haven't already."


Have feedback? Email us at
Email Scott Lucas at
Follow us on Twitter @sanfranmag
Follow Scott Lucas on Twitter @ScottLucas86