There's a few articles that go into a loosely defined faulting area dubbed the Walker Lane[1][2][3] in which it's theorized that the East Pacific Rise (a rift), under the Gulf of California, may be expanding directly north. I know some geologists were surprised at first at the 7.4 Landers earthquake in 1994, and the article goes into that the Walker Lane seems to follow US 395, so I wonder if this is just a continuing extension of geologic activity associated with it.