San Ramon Earthquake Swarm Tops 600, Activity Has Now 'Died Off:' USGS

By Lisa Fernandez

NBC Bay Area's quake map shows all earthquakes recorded near the San Francisco Bay Area over the past 24 hours.

An earthquake swarm in the East Bay topped 600 quakes in about a month - breaking a record set in 2003 - but has been quiet in the last two or three weeks, the US Geological Survey said.

Senior USGS research Geologist David Schwartz told NBC Bay Area on Friday said there were 617 mostly small earthquakes that struck San Ramon since Oct. 13. That's almost six times the number that hit the same area in 2003, when 120 earthquakes hit over 31 days, with the largest clocking in at a magnitude of 4.2.

No earthquake during this latest swarm came close to a magnitude of 4.0.

But since Nov. 2, Schwartz said that the "swarm has been quiet. Activity has really subsided. It's really died off."

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