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