Light quake shakes San Francisco; no immediate damage reported
A technician of the French National Seism Survey Institute (RENASS) presents a graph of an earthquake. (AFP)

A shallow but light earthquake shook the San Francisco Bay Area of California early on Thursday, waking many, but there were no immediate reports of damage.

The United States Geological Survey said the quake was of magnitude 4.5 and its epicenter was in Berkeley, across the bay from San Francisco, at 2:39 a.m. (5:39 ET).

A California Governor's Office of Emergency Services spokesman said in an email that there were no reports of harm to the region.

"Since everyone in the Bay Area is awake, it's time for the 30 minute dance party! #earthquake," a Twitter user with the name @Troop206Oakland wrote in a message, as the social media service lit up with comments, many lighthearted.

(reporting by Peter Henderson and San Francisco Bureau reporters, editing by John Stonestreet)