Scientists eyeing small quakes for fault trauma

Three more earthquakes -- one capable of causing at least moderate damage -- rocked the area around the Salton Sea Monday at a time when scientists are watching closely to see if small faults crossing under the lake are transferring energy to the more dangerous San Andreas fault.

The latest quakes to hit the area occurred early Monday morning, including a magnitude-4.8 shaker at 4:55 a.m., its epicenter 3 miles south of Bombay Beach and 90 miles east-northeast of San Diego, according to the U.S. Geological Survey.

That quake, which was big enough to cause moderate damage, was followed by a magnitude-2.7 temblor four minutes later and a magnitude-3.0 shaker at 6:52 a.m., according to the USGS. All three quakes had their epicenters in the same area.

Scientists are particularly interested in the area because an earthquake that starts in Bombay Beach in Imperial County and ripples northwest along the San Andreas fault could be the Big One that devastates Los Angeles, Graham Kent, a research geophysicist at UC San Diego, told the Los Angeles Times.

The quakes appeared to be tapering off by Monday afternoon, according to the monitoring system run by the USGS and Caltech in Pasadena.

In a 48-hour period starting Saturday morning, 42 quakes shook just south of Bombay Beach on the Salton Sea, ranging in magnitude from 0.5 to 3.3.

These quakes appear to be taking place at the hazy intersection of several recently mapped faults crossing beneath the Salton Sea and the the San Andreas fault, according to the newspaper.

The worry for scientists comes from a case in 1987, when a magnitude-6.2 earthquake on one of the crossing faults appeared to trigger a 6.6 quake 12 hours later on the Superstition Hills fault to the south.

But the the last time a swarm of this type occurred in the area was 2001, so they are not especially unusual, Caltech seismologist Kate Hutton told The Times. She said scientists do not yet know if quakes this small can trigger anything dangerous on the San Andreas.

   
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