The area east of San Diego near California's border with Mexico
was hit by "a swarm" of several hundred earthquakes on Sunday,
with the strongest clocking in at a magnitude 5.5, but no major
damage was reported. Still, the shaking in the area known as the
Imperial Valley was the most significant activity on record
since the '70s, U.S. Geological Survey seismologist Lucy Johnson
said. Of the 300 quakes that were recorded by Sunday evening,
more than 30 were magnitude 3.5 or greater. Only minor damage
had been reported, said Robert Graves, another USGS
seismologist. Graves told reporters that about 300 quakes had
been recorded by Sunday evening. More than 30 had a magnitude
over 3.5, and the biggest "are a little bit larger than what we
have seen in these types of processes in the past." Graves said
the area is a "zone of transition" between the Imperial and San
Andreas faults and tends to have more frequent earthquake
activity than other parts of California. He said that previous
swarms -- some of which were r