AVILA BEACH, Calif. -

Southern California residents are already shaken up by Friday night's temblor, and now some are see a letter online that says there may be an even bigger one coming.

They should be relieved to know that letter is fake, and USGS wants everyone to know they didn't write it.

The letter warns Orange County communities to prepare for an earthquake up to magnitude-7.4.

The letter boasts USGS' official logo and it's signed by a “George E Dickson III,” whom we found does work for Seismic Warning Systems, a company mentioned in the letter, but does not work for USGS which the letter claims to be written by.

USGS says it's a mean joke to those who were just rattled by the 5.1 quake on Friday.

Central coast residents aren't laughing, especially those who live near the fault line or the Diablo Canyon power plant.

USGS wants the public to know that they don't predict earthquakes?they only provide information for ones that have already occurred.

For official information from USGS, visit earthquake.usgs.gov.