About San Andreas Fault

Introduction:

The San Andreas fault,the boundary between two moving plates formed between 15 to 20 million years ago.San Andreas fault id located in San Francsco,San Berardino,San juan Bautista.On the year 1895 San Andreas is officially defined which is named by Andrew Lawson.

 


Img:San Andreas Fault

Depth:

The San Andreas Fault is more than 800 miles long and extends to deep of at least 10 miles within the earth.The fault is a complex zone of crushed and broken rock form a few hundred feet to a mile wide

 Why is San Andreas fault is important?

California's Sleeping giant,the San Andreas fault,markes the slippery yet sticky boundary between two of Earth's tectonic plates.It is responsible for the biggest earthquake in California upto magnitude 8.1.

What type of fault is the San Andreas? 

A san Andreas earthquake would be classified as occurring on the strike-slip fault.Strike-slip fault are found along boundries of tectonic plate sliding past each other.

 

Img:strike-slip fault

Some facts about San Andreas fault

  • The fault divided into three segment each with different characterictics and dfferent degree of earthquake risk.The most significant being the southern segment,which passes within about 35 miles of Los Angeles.
  • The Pacific plate,to the west of the fault,is moving in a northwest direction while the north americal plate to the east is moving towards the southwest,but relatively southwest under the influence of plate tectonics.The rate of slippage average about 33 to 37 milimeters in a year across california.
  • Currently,it is believed that the modern San Andreas will eventually transfer its motion towards a fault within the Estern California share zone.
  • A project called the San Andreas Fault Observatory at Depth(SAFOD)neae parkfield monterey county,is drilling into the fault to improved prediction and recording of future earthquakes.

San Andreas Fault has had some notable earthquake in history

  • 1857 Fort Tejon earthquake:

About 350 kilometers(200mi)were ruptured in central and southern California.Though it is known as the Fort Tejon Earthquake,the epicentre is thought to have been located far to the north,just south of Parkfield.Two deaths were reported its moment magnitude was 7.9.

  • 1906 San Francisco Earthquake: 

About 430 kilometers(270mi) were ruptured in Northern California.The epicentre was near San Francisco.At least 3000 people died in the earthquake.The magnitude was estimated to be 7.8.

  • 1957 San Fransisco Earthquake :

A magnitude 5.7 quake with and epicentre on the San Andreas Fault in the ocean west of San Franscisco and Daly City.

  • 1989 Loma Prieta Earthquake: 

About 40 kilometers(25mi) were ruptured(although the ruptured did not reach the surface) near Santa Cruz,California, causing 63 deaths and moderate damage in certain vulnerable location in the San Francisco Bay Area.Momemt magnitude was about 6.9.This quake occurred on october 17,1989,at approx 5.4pm PDT.

  • 2004 Parkfield Earthquake:

On september28,2004 at 10.15 am PDT,a magnitude of 6.0 earthquake struck the Parkfield area,including the San Francisco Bay Area.

 Thank you;


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