Anniversary earthquake measures 3.8 on San Francisco peninsula
By Lisa M. Krieger
Posted: 04/18/2011 03:56:07 PM PDT
Updated: 04/18/2011 04:54:49 PM PDT
On the 105th anniversary of the giant 1906 San Francisco earthquake, the San Andreas fault woke up with a small shrug.
A 3.41 magnitude quake was reported at 2:57 p.m. on Monday afternoon, with an epicenter 8.5 miles deep located halfway between Millbrae and Pacifica, near the north end of Crystal Springs Reservoir, according to U.S. Geological Survey spokesman Paul Laustsen. The tremor was felt from San Jose to Oakland.
At 5:12 a.m. April 18, 1906, San Franciscans were jarred awake by a massive magnitude 7.9 earthquake, which caused buildings to crumble and killed an estimated 3,000 people, according to recent updated calculations by USGS.
Scientists believe there is a 62 percent chance another earthquake rivaling the "great one" in 1906 will hit the San Francisco Bay area within the next 30 years.
That quake caused millions of dollars worth of damage in California from Eureka to Salinas, measured an estimated 8.3. During that event, roads, fences and rows of trees that crossed the fault were offset several yards, and the road across the head of Tomales Bay, part of today's Point Reyes National Seashore, was offset almost 21 feet.
"If the 105th anniversary of the 1906 earthquake failed to serve as a reminder to get your emergency kits ready, perhaps the 3.8 we just had will do!" tweeted Jeffrey's Natural Pet Foods in San Francisco.
The San Andreas fault system -- a complex network of many intricate faults -- forms a continuous
narrow break in the Earth's crust that extends from northern California southward to Cajon Pass near San Bernardino. It is a "strike slip" fault, caused by a fracture of two crustal plates. The Pacific Plate, on the west, moves northwest relative to the North American fault, on the east.
LINK: Anniversary earthquake measures 3.8 on San Francisco peninsula - San Jose Mercury News