Southern California Town Rings In New Year With ‘Earthquake Swarm’

Southern California Town Rings In New Year With ‘Earthquake Swarm’
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More than 100 small earthquakes have struck the Southern California-Mexico border since Saturday. But while “quake swarm” sounds like the term Morgan Freeman uses in the disaster movie right before Los Angeles cracks off into the ocean, real scientists say this particular event is nothing to worry about.

A M 2.5 earthquake struct near Brawley, California on Sunday (star). Dozens of earthquakes were recorded in the area over the weekend.

The town of Brawley, California rang in the New Year with dozens of earthquakes, the LA Times reports. But most of them were too weak to be felt or noticed by people, with the strongest quake in the sequence registering a magnitude 3.9. So-called quake swarms are standard fare along the Brawley Seismic Zone, a strip of land connecting the San Andreas and Imperial faults. (A swarm of over 300 small earthquakes struck the same region in August 2012.)

The precise reason quake swarms occur is not well-understood. They tend to garner attention when they do, however, because of their potential to trigger larger, deadlier earthquakes. But according to geologists, California’s latest swarm is too far south from the infamous San Andreas fault to tip off the magnitude 7+ apocalypse quake everybody’s bracing for. 

“If they happened a mile [1.6km] away we would be concerned, but these quakes are about 30 miles [48km] from the San Andreas Fault,” Caltech seismologist Lucy Jones told CNN.

In September, a quake swarm struck the northern end of the Brawley Seismic Zone, with over 140 individual tremors recorded under the Salton Sea. That event was close enough to the southern extent of the San Andreas fault to dramatically boost the risk of a major earthquake for a short period of time. Fortunately, the Big One never came.

[LA Times, CNN]