San Andreas Fault, California
The San Andreas fault zone, which is about 800 miles long and at least 10 miles deep, slices through two-thirds of the length of California. The Pacific Plate, on the west side of the fault zone, has been grinding in a northwesterly direction past the North American Plate for millions years, at a rate of up to 2 inches per year.
The 1906 earthquake, which measured an estimated 8.3 on the Richter scale, was one of the worst natural disasters in North American history, causing around 3,000 casualties. The major rupture occurred along the San Andreas fault off the San Francisco coast and stretched almost 300 miles from north to south. Fires raged for days, damaging much of the city’s infrastructure.
The San Andreas fault zone creeps in some places, especially in its northern section, and is fixed in others. In the area of Cholame, a community in San Luis Obispo County, underground energy is steadily building up. Smaller tremors have plagued the region since the recent magnitude 6 quakes in San Simeon and Parkfield, which, scientists speculate, might be a sign of a forthcoming large earthquake.
Image: USGS / Google Earth