Series of quakes rock San Diego region
http://www.utsandiego.com/news/2012/aug/26/series-quakes-rock-region/
by Gary Robbins
1:01 p.m., Aug. 26, 2012
Updated 1:11 p.m.
A series of three sizable earthquakes erupted early Sunday afternoon on the San Andreas fault, south of the Salton Sea, causing shaking that was felt across the region from San Diego and Imperial counties to northern Orange County.m
The first quakehead a 5.3 that occurred four miles southeast of Westmorland at 12:30 p.m, according to the U.S. Geological Survey.
That was followed one minute later by a 5.4 quake in the same area. Then there was another 5.3 at 12:32 p.m. a short distance away, the USGS said.
Since then there have been two quakes above 3.1 and two quakes above 4.0 in that area.
Three quakes of that size close in time is unusual, but it does not necessarily mean a larger event is imminent, earthquake experts.
However, the quake occurred at the very southern end of the San Andreas. Scientists are concerned that the entire stretch of the San Andreas will someday snap, causing a catastrophic quake.
The quake caused a lot of shaking in the heavily congested stands at the Del Mar race track and people did look around but there was no panic.
Tom Rockwell, seismologist at SDSU said: “Today’s event occurred in the Brawley Seismic Zone, an area where the San Andreas and Imperial faults come together. It’s a very seismically active region.:
But Rockwell said having three 5.0 earthquakes is very unusual so close in time.
“The big concern is if a moderate earthquake would lead to a larger earthquake on the San Andreas,” Rockwell said.
Thanks for the update. YES, the number of these quakes is very unusual.
I’ve got the earthquake, real-time list going for the USGS. Almost all the quakes for the last 4 hours in Brawley just spit out the “computer message, not reviewed by a seismologist”. Wondering why? I can’t fathom a reason unless their computer has taken over. (slight attempt at humor) Any ideas?
“However, the quake occurred at the very southern end of the San Andreas. Scientists are concerned that the entire stretch of the San Andreas will someday snap, causing a catastrophic quake.”
The Southern end of the San Andreas fault is way overdue for the “big one”.