Rate of Earthquake Swarm in Mammoth Area Slows
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A weeklong swarm of hundreds of small earthquakes dwindled to about 20 Sunday in the Mammoth Lakes area, and all of the newest temblors were too small to be felt by residents, the U.S. Geological Survey reported.
Scientists believe most of the quakes to be volcanic in origin, with some slow quakes lasting 20 minutes or more, reflecting movement of magma eight miles or more beneath the surface.
The strongest quake of the series, last Thursday, measured only a mild magnitude 3.0. It was situated five miles southeast of Mammoth Lakes. Most of the quakes were centered immediately northeast of the Eastern Sierra ski resort and measured less than 2.0.
Meanwhile, the Geological Survey said, aftershocks continued over the weekend in an area near the intersection of the San Andreas and San Jacinto faults, four miles northwest of San Bernardino.
The strongest of the new aftershocks in this series was a magnitude 3.6 on Saturday morning. The main shock on June 28 registered a moderate 4.2.
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