Long Valley was formed 760,000 years ago when a huge volcanic eruption released very hot ash that later cooled to form the Bishop tuff that is common to the area. The eruption was so colossal that the magma chamber under the now destroyed volcano was significantly emptied to the point of collapse. The collapse itself caused an even larger secondary eruption of pyroclastic ash that burned and buried thousands of square miles. Ash from this eruption blanketed much of the western part of what is now the United States. Geologists call topographic depressions formed in this manner calderas.

Originally posted by blamethegreys
As far as science understands faults and plate tectonics, California is not going to fall into the ocean. If it does, modern geologic science will have to throw out most all their reference books and start from scratch.

I noticed looking at the maps that there were several small quakes west, in the Mammoth Lakes area that could have shifted tensions to the east, causing this week's quakes.

Mammoth is actually a very active region, and a hot spot like yellowstone is as well, so quakes in the region aren't out of place at all.

en.wikipedia.org...