At least 5 earthquakes strike San Francisco Bay Area on Sunday

SAN FRANCISCO, May 3 (UPI) -- Residents of the San Francisco Bay Area were a bit startled when they felt the ground beneath them shaking from at least five earthquakes on Sunday, officials said.

Scientists said a 4.0-magnitude earthquake struck near Concord, a suburb located about 30 miles northeast of downtown San Francisco, at about 2:15 p.m. local time Sunday.

The U.S. Geological Survey said the movement, though, could be felt by much of the Bay Area -- though experts described the sensation as a quick jolt.

About 10 minutes earlier, a 2.5-magnitude tremor struck that same area -- which was followed by quakes measured at magnitudes of 2.7, 2.4 and 1.6 within the next 45 minutes.

The seismic events shook buildings and homes, mostly in the East Bay region -- which lies west of the Oakland-San Francisco Bay Bridge -- but no injuries or damage were initially reported.

The USGS measured the earthquakes about nine miles underground.

Thousands of Bay Area residents reported feeling the series of tremors to the USGS's reporting website and wrote of the shaking on social media channels.

"Bay Area update: we recently had a baby earthquake in concord (I'm scared)," a Bay Area resident tweeted.

Also Sunday, about 400 miles to the south, a 3.9-magnitude quake {link:struck near Los Angeles just after 4 a.m. local time.

"Anyone else in LA get woken up by the earthquake at around 4am? I thought I was dreaming!" one resident tweeted.

The Los Angeles Fire Department said it briefly went into "earthquake mode" Sunday morning, performing a series of safety checks and surveys for nearly 500 square miles around the city. No damage and no injuries were reported.

A similar 3.5-magnitude quake shook L.A. last month.

California is a hotbed of seismic activity because the state is comprised of numerous geologic fault lines -- the most famous and most dangerous of them all being the San Andreas Fault.

One person died last August when a 6.0-magnitude quake struck in the North Bay, but the area hasn't seen a large-scale catastrophic seismic event since the Loma Prieta quake decimated parts of San Francisco and killed 63 in 1989.

No one has died from a Los Angeles area earthquake since a 6.7-magnitude quake struck Northridge in 1994, killing 60 people.