4.5 earthquake shakes Bay Area Monday night

A magnitude 4.5 earthquake struck at 10:33 PM local time in Pleasant Hill, California. A magnitude 4.5 earthquake struck at 10:33 PM local time in Pleasant Hill, California. Photo: USGS Photo: USGS Image 1 of / 24 Caption Close 4.5 earthquake shakes Bay Area Monday night 1 / 24 Back to Gallery

A 4.5 magnitude earthquake shook the Bay Area late Monday night, the USGS reported.

The epicenter of the 10:33 p.m. earthquake was less than a mile from Pleasant Hill in Contra Costa County. The shaking could reportedly be felt as far away as Chico, Lake Tahoe, and Salinas, according to a map released by USGS.

BART reported that the earthquake would affect their operations.

"Earlier, an earthquake had been felt within the area serviced by BART," they wrote on Twitter. "Trains are running at reduced speeds completing track inspections. Please expect residual delays of 10-15 minutes throughout the BART system. Thank you."

The Contra Costa Sheriff Department tweeted that they received no calls for injuries or damage related to the tremor.

Initially reported as a magnitude 4.7, the earthquake was later revised to a 4.5. A smaller 2.5 earthquake preceded it at roughly the same location at 10:23 p.m.

A multitude of aftershocks followed the 4.5 quake. The largest registered a 2.1 magnitude.

Observers noticed the epicenter of the quakes was near the 80-mile long Concord-Green Valley Fault. The Chronicle reported the earthquake occurred on a previously unmapped fault between the Concord and Calaveras faults.

MORE: Seismologists weigh in on Bay Area earthquake, 26 aftershocks follow

Patrycja Moszczenska, a graduate student from Poland living in Danville, said the tremor jolted her awake. "It woke me up. Didn't know what was going on. My whole bed and house was shaking," she told SFGATE. "Scariest experience ever."

As always, Bay Area residents took to Twitter to share their observations about the earthquake, which was a bit larger than the usual shaker.

"Y’all up?" the San Jose Earthquakes soccer team wrote, cheekily.

ALSO: 'That quake was not playin:' Bay Area reacts to earthquake with hilarious tweets

"The algorithmic timeline has ruined Earthquake Twitter," wrote another user.