A small earthquake shook the northern Peninsula on Wednesday evening, Oct. 28. The U.S. Geological Survey lists it as magnitude 2.73, centered about 2 kilometers northeast of Pacifica.
The details
The quake hit at 5:17 p.m., NBC Bay Area reported, citing the USGS. The station said it was centered 1.3 miles northeast of Pacifica, 3.2 miles west of San Bruno and 3.9 miles west-southwest of South San Francisco. The USGS event page lists a depth of about 6.5 kilometers, or roughly 4 miles.
A quake of this size rarely causes damage, and none was reported. But it was widely noticed. As of Friday, the USGS "Did You Feel It?" page showed more than 500 responses, with a top community intensity of about 3.8. That is roughly the level of light shaking that rattles windows and dishes.
Why the area shakes
Pacifica sits close to the San Andreas Fault, which runs just offshore along this stretch of coast before heading down the Peninsula through the Crystal Springs reservoirs. The USGS has not tied this small quake to a particular fault. Small quakes like this are common in the Bay Area and do not mean a larger one is coming.
Be ready
Experts recommend keeping water, food, medications and a flashlight on hand, and securing heavy furniture. If you feel shaking, drop, cover and hold on. You can report shaking to the USGS through its "Did You Feel It?" tool on the event page. For more on preparedness, see our guide to the Great California ShakeOut.