An earthquake with a preliminary magnitude of 4.5 centered in Contra Costa County was felt in the Menlo Park area on Monday night.
The temblor struck at 10:33 p.m. in an area less than a mile away from Pleasant Hill and about 2.2 miles away from Walnut Creek, according to the U.S. Geological Survey in Menlo Park. It had a depth of 9.1 miles.
Some Bay Area residents, including people in Menlo Park and surrounding cities, took to Twitter minutes after the quake with reactions to the jolt.
"That was an #earthquake just now! small but noticeable in Menlo Park," tweeted Christine Loredo, founder and vice president of Yodlee Incubator.
"Did anyone feel a mild earthquake just now down here in Menlo Park?" tweeted Carolyne Zinko, editor-in-chief of Modern Luxury Silicon Valley magazine.
The 4.5-magnitude earthquake was preceded by a 2.5-magnitude temblor at 10:23 p.m.
A larger earthquake with a magnitude of 4.8, which struck shortly before 1 p.m. today (Oct. 15) about 10 miles away from Tres Pinos, was also felt throughout the Bay Area.