No injuries have so far been reported after a 5.1 earthquake hit the Northern Californian coast 70 miles west of Ferndale. According to the United States Geological Survey website, the quake struck at 0416 this morning Pacific time.
The largest earthquake to hit California was a 7.9 in 1887. According to the USGS:
This earthquake occurred on the San Andreas fault, which ruptured from near Parkfield (in the Cholame Valley) almost to Wrightwood (a distance of about 300 kilometers); horizontal displacement of as much as 9 meters was observed on the Carrizo Plain. It caused one fatality. A comparison of this shock to the San Francisco earthquake, which occurred on the San Andreas fault on April 18, 1906, shows that the fault break in 1906 was longer but that the maximum and average displacements in 1857 were larger.
California sits in an area that is geologically very active. Plate margins grind against each other causing the tremors. The San Andreas Fault is a huge gash in the landscape that runs from Cape Mendocino down to the Mexican border. It’s a transform or slide fault. The leading edge of the North American Plate and the Pacific Plate slide past each other.
They move in small fits and starts but on occasion get stuck. The pressure builds and builds, until whatever prominence of rock holding them in position gives way, and the plates move causing an earthquake.
This post was published at The Daily Sheeple on January 2nd, 2015.