My understanding is that the fault through CA is actually a side-by-side, not an over-under. If so, this would mean that, although CA may suffer bad earthquakes, it will never “fall off” because of one.
Where the SA runs through the Puget Sound near Seattle, however, it is an over-under. While they do not make predictions of WA or Seattle “falling off,” there is quite a bit of evidence that the Cascade Fault creates massive damage every 500 years or so. And they are due for a return.
Thanks for that info. I like the pizza example below..
http://geology.com/articles/san-andreas-fault.shtml
The San Andreas Fault is the sliding boundary between the Pacific Plate and the North American Plate. It slices California in two from Cape Mendocino to the Mexican border. San Diego, Los Angeles and Big Sur are on the Pacific Plate. San Francisco, Sacramento and the Sierra Nevada are on the North American Plate. And despite San Francisco’s legendary 1906 earthquake, the San Andreas Fault does not go through the city. But communities like Desert Hot Springs, San Bernardino, Wrightwood, Palmdale, Gorman, Frazier Park, Daly City. Point Reyes Station and Bodega Bay lie squarely on the fault and are sitting ducks.
The San Andreas Fault is a transform fault. Imagine placing two slices of pizza on the table and sliding them past one another where they touch along a common straight edge. Bits of pepperoni from one side crumble across the boundary onto the anchovy side. The same thing happens with the fault, and the geology and landforms along the mighty rift are extremely complicated.