The San Andreas Fault

The San Andreas Fault

What is the San Andreas Fault?

The San Andreas Fault is the gliding boundary in between the Pacific Plate and the North American Plate. It slices California in 2 from Cape Mendocino to the Mexican border. Moreover, despite San Francisco’s legendary 1906 earthquake, the San Andreas Fault did not go through the city. However, neighborhoods like Desert Hot Springs, San Bernardino, Wrightwood, Palmdale, Gorman, Frazier Park, Daly City, Point Reyes Station, and Bodega Bay exist squarely on the fault and are easy targets.

San Andreas Map: The red line on this map complies with the surface area trace of the San Andreas Mistake across California. Areas to the east (ideal) of the mistake get on the North American tectonic plate. Areas to the west (left) of the respondents become part of the Pacific tectonic plate. The arrows show the directions of relative movement along the fault. Map copyright by David Lynch.


What Type of Fault is the San Andreas?

As written before the idea of placing two slices of pizza on the table and sliding them over each other where they touch along a usual straight edge – pieces of pepperoni on one way collapses along the edge to the anchovy side.


Exactly how Fast Does It Relate?

The plates are gradually passing one another at several inches a year – roughly the same pace that your fingernails grow. However, this is not a constant motion, and it is the average movement. The plates will undoubtedly be locked with no movement whatsoever as they press against one another for several years. Suddenly, the built-up stress breaks the rock along the fault, and the plates slip a couple of feet simultaneously. The damaging rock sends waves in all directions, as well as it is the waves that we feel as earthquakes.

Is the Fault Visible at the Surface area?

The photo shows a plate boundary. Picture of the San Andreas Fault near Gorman, California, showing rocks in the Pacific plate (gray rocks on the left side of the fault) and the North American plate . There are very few locations on Earth where two plates can be seen in contact like this. Picture taken by David Lynch.

In lots of areas like the Carrizo Plain (San Luis Obispo County) and the Olema Trough (Marin County), the mistake is easy to view as a series of scarps and pressure ridges. It is a lot more refined in other places since the fault has not moved in several years and is covered with alluvium or disordered with a brush. In San Bernardino as well as Los Angeles Counties, a lot of the roadways along with the mistake puncture fantastic mountains of cut, the powdery, fallen apart rock that the moving plates have grated.

The characteristic of the San Andreas Fault is the various rocks on either side of it. Being about 28 million years old, rocks from country miles have been juxtaposed against rocks from extremely various locations and origins. The Salinian block of granite in central and north California originated in Southern California, as well as some even state north Mexico. Pinnacles National Monument in Monterey County is just half of a volcanic complex. The various other components are 200 miles southeast in Los Angeles County and referred to as the Neenach Volcanics.

Fault Myths

Offset Drainage: Photograph copyright by David Lynch.

Fault’s Myths

There are several myths and tales regarding the San Andreas Fault; the most prominent is that it will indeed crack, and California will slide right into the sea. WRONG! It will not happen, and also, it can not occur. Nor exists anything such as “earthquake weather” or chosen times of day when earthquakes strike.

The Globe’s Most Famous Fault

The San Andreas Fault is a lot more accessible than any other fault on the planet. With California’s big populace and temperate environment, numerous roadways snake along the fault. They are spacious and relaxed, best for family getaways. There is excellent camping, bird viewing, wildflowers and wildlife, rock collecting, and natural beauty along the road. State and National parks are lined along the fault like beads on a string. All it takes is an excellent map, a comfy vehicle, and a desire to see the world’s most well-known fault.


Originally published on Geology.com by David K. Lynch, PhD, author of SanAndreasFault.org.

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