What caused the San Andreas fault?
May 09, 2010
in
Earthquake Questions
I know it causes earthquakes, but what actually caused the fault line to appear?
Thanks! :]
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3 comments
Eclogite on May 9, 2010 at 3:02 am
The San Andreas Fault is a tectonic boundary that separates the North American Plate from the Pacific Plate. The North American Plate is moving toward the southwest and the Pacific Plate is moving toward the northwest, resulting in apparent north/south movement along the San Andreas Fault Zone. The appearance of the fault line is due to sinstral (top to left) transform motion along the plate boundary.
o2bagooner on May 9, 2010 at 3:02 am
and today’s phd thesis question…. LOL
short answer is that there are three tectonic plates colliding, scraping and grinding against each other in california, the north american, pacific and (if memory serves me right) the juan de fuca plate.
the SAF is where the boundary of the JDF and the NA plates express themselves on the surface. unlike the majority of the NA plate boundaries the JDF is not subducting below the NA but is sliding past it which is one of the reasons that the earthquakes are so shallow and destructive
Lil Wayne wifey aka Mrs.Carter on May 9, 2010 at 3:02 am
Scientists have learned that the Earth’s crust is fractured into a series of "plates" that have been moving very slowly over the Earth’s surface for millions of years. Two of these moving plates meet in western California; the boundary between them is the San Andreas fault. The Pacific Plate (on the west) moves northwestward relative to the North American Plate (on the east), causing earthquakes along the fault. The San Andreas is the "master" fault of an intricate fault network that cuts through rocks of the California coastal region. The entire San Andreas fault system is more than 800 miles long and extends to depths of at least 10 miles within the Earth. In detail, the fault is a complex zone of crushed and broken rock from a few hundred feet to a mile wide. Many smaller faults branch from and join the San Andreas fault zone. Almost any road cut in the zone shows a myriad of small fractures, fault gouge (pulverized rock), and a few solid pieces of rock.
or
http://www.desertusa.com/mag06/mar/san_andreas.html