San Andreas: Separating 5 Facts From Earthquake Fiction

Sometime in the future, cafés in Kathmandu will be abuzz about a devastating magnitude-8 earthquake, except this time the temblor will have been half a world away, in California, where the San Andreas Fault will have finally ruptured after a long period of dormancy.

Although criticism of the recently released film San Andreas from scientific circles is a certainty, as a state seismologist for Nevada, with responsibility for monitoring Nevada and parts of eastern California, I welcome this movie and hope it marks the beginning of a serious conversation about the real consequences of a large earthquake in modern America. Whatever the scientific flaws of San Andreas may be — and they are plenty — the consequences of a large urban earthquake remain unnerving.

With a little help (OK, a lot of help), Hollywood went with the “wall-to-wall” scenario and ruptured the entire San Andreas Fault, extending from near the Mexican border almost to Oregon. This kind of rupture has never been seen and is a highly unlikely scenario given both historic and paleo-earthquake records. And in reality, the magnitude would be closer to 8.3, not 9 as depicted in the movie.

Of course, Hollywood paints a bigger-than-life picture and plays with the truth in order to entertain, so let’s try to separate fact from fiction with this latest take on the disaster genre.

Here are five truths about the depictions in San Andreas:

  1. The trigger: Can a large earthquake in Nevada trigger the San Andreas Fault or knock down Hoover Dam like in the movie? Western Nevada and eastern California occupy the Walker Lane, which has some fault lines that are capable of generating quakes with magnitudes up to about 7.5 (just not near Hoover Dam). Larger Nevada earthquakes can trigger other regional earthquakes; it happened in reverse in 1992, when the —> Read More