Quake swarm near the California-Mexico border gets scientists’ attention

A swarm of more than 250 small earthquakes have struck since New Year’s Eve near the California-Mexico border, causing unease among residents and attention from scientists.

The strongest earthquake in the sequence was magnitude 3.9, striking directly underneath the town of Brawley, about 170 miles southeast of Los Angeles.

The earthquakes struck in the southern end of the Brawley Seismic Zone, a seismically active region where tectonic plates are moving away from each other and the Earth’s crust is getting stretched out “and basically adding land,” said Caltech seismologist Egill Hauksson.

The Brawley Seismic Zone is particularly important to watch because it is the region that connects the San Andreas and Imperial faults, both of which can produce damaging earthquakes. The seismic zone extends for about 30 miles from the city of Brawley, across the Salton Sea’s southern half, and ends near Bombay Beach.

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