|A swarm of quakes, one measuring 4.0, struck the East Bay.|
May 3, 2015 - CALIFORNIA, UNITED STATES - A string of moderate earthquakes has rattled the East Bay Sunday, shaking buildings. There were no immediate reports of injuries or damage.
The U.S. Geological Survey says an earthquake with a preliminary magnitude of 4.0 hit at 2:13 p.m. Sunday. It was centered a mile south of Concord, along the Concord fault.
Three smaller quakes shook the area in the moments before and after the larger one. A magnitude 2.5 earthquake hit at 2:01 p.m., followed by the 4.0 at 2:13, and a 2.7 magnitude quake at 2:14 p.m. A magnitude 2.4 shook the area again at 2:28 p.m. A magnitude 1.6 hit at 2:56 p.m.
The earthquakes struck at a depth of 8 to 9 miles.
Thousands of Bay Area residents reported feeling the shaking on the USGS Did You Feel It site, and on social media sites like Twitter.
Irish Girl tweeted, “Nothing like an Earthquake to shake up a lazy Sunday!”
Yo~ongie tweeted, “@BamBam1A did you feel the earthquake? Welcome to the state of Earthquakes.”
In Southern California, a magnitude of 3.9 hit the Los Angeles area at 4:07 a.m. Sunday. That quake was centered a mile northwest of the View Park-Windsor Hills neighborhood, just north of the cities of Inglewood and Culver City. A magnitude-3.5 earthquake hit that same area on April 12.
|Multiple earthquakes struck the East Bay near Concord on Sunday. (cbsSF)|
The Los Angeles quake struck while many residents were sleeping, and the timing of the Bay Area quakes Sunday was not lost on social media users.
Zachary Burkett tweeted, “It was nice of the northern California earthquake to show up in the mid afternoon instead of the stupid 4 AM jolt down here this morning.”
The Los Angeles Fire Department said in a statement early Sunday that it briefly went into “earthquake mode.” The alert was lifted after fire officials surveyed more than 470 square miles in the Los Angeles area and conducted safety checks.
Strong earthquakes with an epicenter off the coast can trigger tsunamis, depending on the size and type of the fault movement. The Pacific Tsunami Warning Center tracks earthquake data for the West Coast. - CBS.
Concord-Green Valley Fault
The Concord-Green Valley Fault is mostly a right-lateral strike-slip fault with up to approximately 4 mm/yr (1/6 inch/year) of creep. The Concord Fault lies to the south of the Green Valley Fault. The total slip rate on the Concord Fault segment is 4 mm/yr (1/6 inch/year) and on the Green Valley Fault segment is about 5 mm/yr (1/5 inches/yr).
The Concord Fault maybe connected to the Greenville Fault through a complex set of faults under Mount Diablo, including the Mount Diablo Thrust. The Concord Fault may also be connected to the northern Calaveras Fault through a complex set of faults south of Walnut Creek. The Green Valley Fault is a direct continuation of the Concord Fault north of Carquinez Straight. The northern end of the Green Valley Fault is not well defined at the surface or from seismicity.
At present, there is little information on the date of the last surface-rupturing event on the Concord-Green Valley Fault. The current best estimate is that the last large earthquake on this fault occurred between 200 to 500 years ago.
The 2003 Working Group for California Earthquake Probability assigned a 4% probability that the Concord-Green Valley Fault system would produce a magnitude 6.7 or larger earthquake in the next 30 years.