USGS: California is not doomed to fall into the ocean


Yet another aftershock of the March 11 earthquake hit Japan today. So it seems like a good time to bring up the United States Geological Survey's fascinating FAQ on earthquake myths. Here's one new thing that I learned.

Q: Will California eventually fall off into the ocean?

A: No. The San Andreas Fault System, which crosses California from the Salton Sea in the south to Cape Mendocino in the north, is the boundary between the Pacific Plate and North American Plate. The Pacific Plate is moving northwest with respect to the North American Plate at approximately 46 millimeters per year (the rate your fingernails grow). The strike-slip earthquakes on the San Andreas Fault are a result of this plate motion. The plates are moving horizontally past one another, so California is not going to fall into the ocean. However, Los Angeles and San Francisco will one day be adjacent to one another!

Image: Photo taken by Wikipedia user Ikluft, used via CC


  1. “However, Los Angeles and San Francisco will one day be adjacent to one another!”

    My first thought was, “Great, this means traffic is just going to get worse.”

  2. Actually, continental crust does not “fall” into the ocean for most other types of faults. It is less dense than oceanic crust and tends to get scaped up on the edges. The exception is when rifting occurs mid continent. If the blocks of crust fall faster than erosion fills the basin and/or the ocean rises fast enough, they will “fall” into the ocean. (inundated by the ocean is a better description)

  3. My geoscience prof in university used to say that Clifornia is going to end up eventually adjacent to Vancouver. In terms of geologic time, of course.

    1. Great, considering so many Angelinos are moving to Seattle and taking it over anyway, now they want to crush us on their way to Vancouver.

  4. I used to hear that all the time from the pulpit in church (former Mormon). It was pretty much accepted as fact that California being swallowed into the ocean was an inevitable harbinger of the second coming. I moved around a lot (military Brat) and this was always the case in every congregation. Could it be that this is a Mormon myth?

    1. I’m LDS and have never heard anyone at church talking about California falling into the ocean, especially not as a “sign of the times.” I may have heard it once from other LDS members, but that was because we lived in Los Angeles and just had an earthquake. The only relation it had to our religion was the fact that we expressed anxiety of not having 72 hr. kits prepared, despite frequent reminders at church.

  5. it’ll all be underwater soon enough, just not from tectonic activity. It’ll be from global warming.

    …..or because all the homosexuals in California caused another great flood, which will be the alternate version that is taught along side “climate change theory” in the south.

  6. Only the strip of California to the west of the San Andreas Fault is headed north; San Francisco is (barely) on the east side of it, while the coastal cities to the south of San Francisco are all on the west. Baja California is also on the northward-moving piece.

    1. you may know this and just didn’t share, that strip is called the Salinian Block and after heading out to sea around Daly City comes back landward at Bolinas Lagoon and runs parallel with Hwy 1 through part of West Marin emerges at the end of Tomales bay, cuts off the Bodega Heads in Sonoma, back to sea until just south of Fort Ross, it starts following a series of gulches and the South Fork of the Gualala River. At Salt Point a the riser of a marine terrace with one of the Pygmy Forest ecological staircases falls directly in to the SA fault before it jumps from the coast to the river and emerges around Pt Arena.

  7. “Los Angeles and San Francisco will one day be adjacent to one another!”
    In only 13-14 million years.

  8. If they’re going to be next to each other, why are we spending billions of dollars on a pork barrel boondoggle High-speed rail network from SF to LA?

    1. If they’re going to be next to each other, why are we spending billions of dollars on a pork barrel boondoggle High-speed rail network from SF to LA?

      Because by the time it’s done, the train will go from SF to Tijuana! Woohoo!

      1. (I should have added the disclaimer that I’m working on the project and it’ll all going well)

  9. I understand there are some strata and a few plants in Inverness, which is to the west of the fault, that are common to Baja, CA..

  10. Actually, it’s a corollary of Murphy’s Law that someday everything *East* of the San Andreas fault will fall into the ocean.

  11. There has already been ~195 miles of movement along the San Andreas fault since its inception. Pinnacles national monument is half of an ancient volcano that was cut in half by the San Andreas fault. The western portion, riding on the Pacific plate resides west of Monterrey, while the eastern half of the volcano, sitting on the North American plate is currently located between Bakersfield and L.A., some 195 miles to the southeast.

  12. In grad school for geology in a SoCal state school, I taught geology 101 lab classes mostly to non-science-majors, and got questions about this kind of thing constantly (especially after the film 2012 came out).

    I had a lot of fun with it because I made sure they understood why such notions are ridiculous (because of how relatively slowly things happen in geology mainly), which they hopefully learned by the end of the course anyway, but I also got them to be frightened (in a good way) about the true dangers to SoCal from large earthquakes that could happen at any time.

    Of course, it’s also a useful exercise when explaining the various movements involved in plate tectonics to show where everything west of the San Andreas is headed eventually.

    Amazingly, though most students were reasonably well educated (they got into a somewhat selective university anyway) and grew up in California, they still had almost no sense of the realities of earthquakes and geology in general.

  13. Man, that would equally piss off all San Franciscan’s and Los Angelenos, both which won’t shut up about how much they’re totally different than the other.

  14. Did anyone ever see that classic old documentary _The_City_That_Waits_to_Die_ with the soundtrack by the Mommas And The Papas?

    1. >So, like, it’s everything EAST of the San Andreas that’s doomed then?

      That’s been my joke since I was a kid. Interestingly enough a lot of the western US is made up of island arcs and other detritus scraped off the Farallon Plate as it subducted below the North American plate. Rather than slipping below th waves, it’s actually gained land.

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