A total of 583 small earthquakes have shaken San Ramon, California, in the last three weeks or so – more than five times the record set 12 years ago, according to the latest US Geological Survey updates.

"It's the swarm with the largest number of total earthquakes in San Ramon," said USGS scientist David Schwartz, who is more concerned about the size of quakes than he is the total number of them. Still, the number tops the previous record set in 2003, when 120 earthquakes hit over 31 days, with the largest clocking in at a magnitude of 4.2.

The largest magnitude earthquake in the current swarm, which began on Oct. 13, is a magnitude 3.6.