The effect of the San Andreas fault as depicted in the movie has about as much relationship to reality as John Cusak's driving as depicted in the movie does to a Sunday afternoon drive.

It's complete fiction.

The San Andreas fault is a strike-slip fault. It represents a boundary between two geological plates (the North American and the Pacific), which are moving past each other.

Within an hour's drive from me is the Pinnacles National Monument, which is the eroded carcass of an ancient volcano. I should say that it is part of the eroded carcass of an ancient volcano. Specifically, it is the western part. The eastern part of the volcano is near Lancaster, CA, which is nearly 200 miles SouthEast. Over the course of 30 million years the fault has moved that much.

The maximum size of an earthquake on the San Andreas fault (currently) is about 8. It can't be much bigger than that, because for a large distance in the central portion of the fault (from Parkfield CA to Hollister CA) the fault exhibits "aseismic creep", meaning that it moves along without causing earthquakes. The size of the earthquake is determined by how large (the length) of a locked section of the fault lets go.

So, contrary to what the movie depicts, (and gee it would be fun to out-drive an earthquake, but alas, impossible) the San Andreas fault can't heave massive blocks of crust into the air in a few moments, it can't split off parts of California and have them sink into the ocean, and it can't create quakes as large as the Chile earthquake.

Another thing people forget, the San Andreas fault is actually well to the East of Los Angeles. Have a look at the USGS map: http://quake.usgs.gov/recenteqs/Maps/Los_Angeles.html

The San Andreas fault is the big one which runs through Palmdale, and then East of San Bernardino. All the little faults in Los Angeles proper are not capable of generating quakes as large as the San Andreas.

The plates can't just upend themselves and sink into the ocean as in the movie. They are far too massive to do this, there is no force that could be applied that would be great enough to cause such an upheaval, and there is no place for them to fall into. The oceans couldn't hold them. Remember that there is crust at the bottom of the oceans as well as continental crust. Imagine something many thousands of miles across and an average of 19 miles thick magically rising up on end and sinking when there is nowhere to sink to.

The Challenger Deep in the Marianas Trench, at 7 miles deep, is the deepest part of any ocean on Earth. Do you think an enormous slab of continental plate 19 miles thick can sink into an ocean with its deepest point only 7 miles?

I guess that I should have written that question better. I was trying to determine if the magnitudes were in Moment Magnitude or measured in another method. Moment Magnitude is a method that I'm not very familiar with. I had found an article that talked about an earthquake around an 8.3 magnitude under the older method of the Richter scale, and it became around a 7.6 magnitude under the Moment Magnitude method. So, it would be prudent to determine which method the website is showing magnitudes in. I can only guess that the USGS supports the website; due to, the magnitudes being in Moment Magnitude in accordance to its Earthquake Magnitude Policy Page.

On the fault map you will see california's faults. Click on one and it will
give you the descriptions like I depicted below. Look at the last 2 responses
to this thread. Anymore questions, feel free to write.

Sorry for the delayed response.

Thank you for giving me the Southern California Earthquake Center's website, I'm not familiar with this website, and I've been having problems locating information on it.

1). What scale is used to determine the magnitude of an earthquake?

2). Where do I look to see the maximum magnitude a fault can produce?

Could you lend me a hand here?

TYPE OF FAULTING : right-lateral strike-slip; minor right-reverse
LENGTH: 210 km, including Coyote Creek fault
NEARBY COMMUNITIES: Lytle Creek, San Bernardino, Loma Linda, San Jacinto, Hemet, Anza, Borrego Springs, Ocotillo Wells
MOST RECENT SURFACE RUPTURE: within the last few centuries; April 9, 1968, Mw6.5 on Coyote Creek segment
SLIP RATE: typically between 7 and 17 mm/yr
INTERVAL BETWEEN SURFACE RUPTURES: between 100 and 300 years, per segment
PROBABLE MAGNITUDES: Mw6.5 - 7.5

COYOTE CREEK FAULT

TYPE OF FAULT : right-lateral strike-slip - ANIMATION
LENGTH: 80 km
NEARBY COMMUNITIES: Borrego Springs, Borrego, Ocotillo Wells
MOST RECENT SURFACE RUPTURE: April 9, 1968, Mw6.5, on southern half; within the last few centuries on northern half
SLIP RATE: between 2 and 6 mm/yr, possibly greater
INTERVAL BETWEEN MAJOR RUPTURES: 100 - 300 years
PROBABLE MAGNITUDES: Mw6.5 - 7.5

HOT SPRINGS and BUCK RIDGE FAULTS

TYPE OF FAULT: right-lateral strike-slip - ANIMATION
LENGTH: 75 km
NEARBY COMMUNITIES: Idyllwild, Mountain Center, Thomas Mountain, Anza
MOST RECENT SURFACE RUPTURE: Late Quaternary; Holocene only at extreme northern end
OTHER NOTES: Probably the least active strands of the San Jacinto fault zone, though the southern Buck Ridge fault is associated with a zone of recent active seismicity.

As in other large fault zones, many of the individual fault strands in the San Jacinto fault zone have their own identities. At its extreme northern end, where the San Jacinto meets the San Andreas fault, this fault zone is made up of several parallel fault strands. The farthest east of these is called the Glen Helen fault; the farthest west is known as the Lytle Creek fault.

One of the larger and more active fault segments, the Casa Loma fault, runs from near Perris Reservoir to just north of Anza. Another large and active named segment is the Clark fault, which runs from near Hemet to just 15 km southwest of the shore of the Salton Sea. The 1954 San Jacinto earthquake probably occurred due to rupture on the Clark fault.

TYPE OF FAULT: right-lateral strike-slip
LENGTH: 1200 km
550 km south from Parkfield; 650km northward
NEARBY COMMUNITY: Parkfield, Frazier Park, Palmdale, Wrightwood, San Bernardino, Banning, Indio
LAST MAJOR RUPTURE: January 9, 1857 (Mojave segment); April 18, 1906 (Northern segment)
SLIP RATE: about 20 to 35 mm per year
INTERVAL BETWEEN MAJOR RUPTURES: average of about 140 years on the Mojave segment;
recurrence interval varies greatly — from under 20 years (at Parkfield only) to over 300 years
PROBABLE MAGNITUDES: MW6.8 - 8.0

San Andreas Fault Zone — San Gorgonio Pass Area:

The San Gorgonio Pass area is fairly complex, geologically speaking. Here the San Andreas fault interacts with other faults (most notably the San Jacinto fault zone and the Pinto Mountain fault) and thereby becomes somewhat fractured, over the distance extending from just north of San Bernardino to just north of Indio, some 110 kilometers (70 miles). Because this deformation has been going on for well over a million years, ancient and inactive strands of the San Andreas fault can be found here. Other faults in this area are have been "reawakened" recently after being dormant for hundreds of thousands of years. There is even evidence to suggest that there is no active, continuous main trace of the San Andreas fault going all the way through the pass, not even at depth — implying that the San Andreas fault may currently be in the process of creating a new fault path through this area! This could also mean that a single, continuous rupture from Cajon Pass to the Salton Sea (a stretch of the San Andreas that has not ruptured in historical times) is unlikely to occur. Fault rupture mechanics are still not well understood, however, and the discontinuity could prove to have little effect on tempering a major earthquake on this southern stretch of the San Andreas fault zone.

Below is a clickable map of the San Gorgonio Pass area, similar to the other clickable maps within these pages; clicking on the surface trace of a fault will take you to a file detailing some of the features of that fault. Cities and towns are shown as diamonds, lakes are shown in light blue, and highways are shown in yellow. It should be noted that due to the complexity of this area, many researchers have used different nomenclature for the local faults, and placed the dividing lines between certain named fault segments in varying places. This naturally makes it difficult to decide upon one standard for labelling maps such as this. When possible, these differences will be noted within the fault files, but keep in mind that the system used here represents only one of many ways of characterizing this intriguing and complex geologic region.

To help reinforce what other's already said, San Andreas Fault is true, and it's a Transform Boundary*. There's another fault zone in the region, but I'd have to double check the name of it. No, California won't sink into the Pacific Ocean.

Ryan, could you provide a link that the San Andreas can only produce magnitude 8 earthquake during a rupture? Or did you mean that the San Andreas Fault has only produced a magnitude 8 earthquake in its recorded history?

Yes, the San Andreas fault does exist, how ever there are faults everywhere on the face of the Earth— Some bigger and some smaller.

The possibility of California or a piece of California being ripped from the continent is as it stands, pure speculation.
Will the San Andreas fault cause an earthquake some time in the future? Of course, just like every other fault line.
How ever no one can say with any amount of certainty just how strong the earthquake will be, if it's disastrous then it will likely be a local event only on the west coast of the United States which is not likely to effect the entire world.

Usually, the only places that you hear about California sinking or separating from the continent due to a massive earthquake is either in SyFy movies or on National Geographic with theoretical disasters.

Contrary to popular belief, California will not 'fall into the ocean'.

The San Andreas fault marks a join between two blocks. The block to the west of the fault is moving to the north-west. This means that eventually (in millions of years) Los Angeles will be north of San Francisco, and San Francisco will be land-locked.