Is there going to be an Earthquake Today in Orange Country...!

No.. there is not going to be an actual earthquake, they are carrting out a drill, to show people how to prepare for a big earthquake if it were to ever happen.

'Great ShakeOut' is being dubbed nation's largest tremor exercise.

More than 5 million people are expected to take part Thursday in what's being billed as the nation's largest-ever earthquake drill – the Great Southern California ShakeOut – and public safety experts hope the event will erase any complacency about preparing for the region's seismic dangers.

"Californians need to be prepared to take care of themselves for at least 72 hours after an earthquake," said Greg Renick of the state Office of Emergency Services.

The Great ShakeOut, a collaborative effort involving corporations, nonprofit groups and government agencies, “gives the public an opportunity to do what they should do in an earthquake,” Renick said.

Students at dozens of Orange County schools, administrators at numerous city halls and staffers at John Wayne Airport's offices will be among the millions who "duck, cover and hold" at 10 a.m. sharp in the mock 7.8 magnitude quake.

The mega-drill comes after a recent forecast concluded that in the next three decades, there's a 67 percent chance the greater Los Angeles area will experience a tremor of at least 6.7 magnitude – the same strength as the 1994 Northridge quake, which killed 57 people.

Thursday's faux catastrophe assumes a massive quake along the southern San Andreas fault, a perpetual seismic specter for inland counties and a less-serious, but still potentially devastating danger to Orange County.

A U.S. Geological Survey projection says a 7.8 magnitude quake along the fault could cause 300 deaths in Orange County and bring down an unspecified 240,000-square-foot mixed-use building.

The Great Shakeout is notable not just for its seven-figure participation, but also for a savvy public relations campaign aiming to transform an ostensibly ho-hum duck-and-cover drill into an attention-grabbing spectacle.

Several YouTube videos have been posted to spark interest, including one that says, "There's more you can do to prepare for the next major earthquake in California," then proceeds to show a man protected only by a helmet getting clobbered in the face with a brick.

On Friday, K-EARTH 101-FM will blare tunes at a "Get Ready Rally" combining music and earthquake presentations at a downtown Los Angeles venue.

Officials have also sought to add realism to Thursday's exercise, offering MP3 downloads of simulated earthquake noise – glass shattering, metal creaking, car alarms going off – that participants can play over loudspeakers during the drill.

A concurrent event Thursday – dubbed Golden Guardian – will gauge the ability of emergency crews to address a huge quake.

Orange County Fire Authority spokesman Greg McKeown said that 58 of 62 fire stations will be involved in the drill by creating divisional command posts in Buena Park, Irvine, Rancho Santa Margarita, Tustin and Laguna Woods. The posts will assess damage to 10 potentially dangerous locations, such as large buildings or bridges.

In Irvine – one of many local cities taking part in the day's events – emergency workers will receive simulated calls from the community, media, law enforcement and other agencies reporting significant damage throughout the region. Community members at Mariners Church will set up a mock shelter for displaced people and pets.

"These exercises allow us to assess strengths and weaknesses and improve our response capabilities in the future," Renick said. "Practice makes perfect."

An aerial view of the San Andreas Fault in the Carrizo Plain National Monument, northwest of Bakersfield.

Earthquake prediction has not advanced far enough to say when earthquakes will occur. At best, geophysicists can say that within x amount of time y number of earthquakes are likely to occur in a location (i.e. 40 earthquakes of Richter scale level 5 or higher in so and so city over the next three hundred years). This would be based on past earthquake records, and not any data about the future.

Prediction is so difficult because of the massive amount of material that is being moved at geologic stress points. In Orange County, the danger from an earthquake is from the San Andres fault in northern California. In that fault, the North American and Juan de Fuca tectonic plates are sliding past each other. Now, you can imagine just how much rock material is contained within each of those plates, and how even the tiniest change in speed or direction could drastically alter the chances of an earthquake occurring.

In the future, perhaps when we have a greater understanding of tectonic plate movement, better sensors and more powerful supercomputers dedicated to earthquake predictions, we will be able to predict such events more accurately, though it would still be a much wider margin than saying "this Thursday."