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San Andreas Fault Facts & Worksheets

The San Andreas Fault is the tectonic boundary that separates the Pacific Plate and the North American Plate.

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The San Andreas Fault is the tectonic boundary that separates the Pacific Plate and the North American Plate. It divides California in half between Cape Mendocino and the border with Mexico.

See the fact file below for more information on the San Andreas Fault, or you can download our 26-page worksheet pack to utilize within the classroom or home environment.

Key Facts & Information

LOCATION AND HISTORY

  • The major Earth’s crustal crack, known as the San Andreas Fault, is located in extreme western North America. From the northern end of the Gulf of California across western California in the United States, the fault trends northwestward for more than 800 miles, heading out to sea into the Pacific Ocean not far from San Francisco.
  • The Pacific Plate and the North American Plate are separated by the San Andreas Fault. It divides California in half between Cape Mendocino and the border with Mexico.
  • About 28 million years ago, the San Andreas fault first formed. California didn’t exist back then, at least not how people know it today.
  • The westernmost point of North America, which at the time stopped at the Pacific Ocean lapping the coastlines of central Utah and Arizona, could be found in bits and pieces. The eastern Pacific contained volcanic islands in other areas.

FORMATION

  • The San Andreas Fault is an example of a strike-slip or transforms fault. In a strike-slip fault, the two sides of the fracture slide horizontally and parallel to the fault. Horizontally, the two sides pass one another. 
  • The San Andreas Fault is, more particularly, a right-lateral transform fault, which implies that if two persons were positioned on opposite sides of the fault, one of them could see the other moving to the right.
  • The distinctive rocks on either side of the San Andreas Fault serve as its identifying feature. 
  • Rocks from far away have been positioned next to rocks from many other regions and origins since they are roughly 28 million years old. 
  • The Salinian granite block found in central and northern California is thought to have come from southern California or possibly northern Mexico. 

FAULT ZONES

  • The fault’s northern segment extends from Hollister through the Santa Cruz Mountains, which served as the epicenter of the Loma Prieta earthquake in 1989, across the San Francisco Peninsula, where Professor Lawson first discovered it in 1895, and finally offshore at Daly City close to Mussel Rock.
  • This was roughly the epicenter of the 1906 earthquake in San Francisco. Just to the north of Stinson Beach in Marin County, the fault comes back on land at Bolinas Lagoon. 
  • Just east of Bodega Head, via Bodega Bay, and back underwater, it returns onshore at Fort Ross through the narrow trough of Tomales Bay that divides the Point Reyes Peninsula from the mainland.
  • From Parkfield to Hollister, the San Andreas Fault’s primary section extends northwestward. While the fault slips continually without creating earthquakes in its center, the southern segment and the portions through Parkfield suffer earthquakes. This process is known as aseismic creep.
  • The southern segment, sometimes referred to as the Mojave segment, starts close to California’s Bombay Beach. The fault’s upturned strata are located in Box Canyon, not far from the Salton Sea. 
  • The fault then continues northwest along the northern base of the San Gabriel Mountains, traverses the Cajon Pass, and follows the southern base of the San Bernardino Mountains.

CURRENT STATUS

  • At about the same rate that your fingernails grow, the plates of the San Andreas fault are gently moving past one another a few inches per year. 
  • However, this is only an average movement and is not a steady motion. The plates will be locked and pushed against one another for years without moving. 
  • As a result of the strain that has been building up, the plates suddenly shift a few feet, breaking the rock along the fault.
  • The waves produced by the shattering rock are what we experience as earthquakes. 

THE NEXT BIG ONE

  • The ShakeOut scenario was developed several years ago by a team of earthquake scientists in order to determine what would actually occur when the Big One eventually strikes. 
  • Seismologists predict how the earth will shake, and other experts, such as engineers and social scientists, then use that knowledge to predict the harm and repercussions that would follow.
  • Furthermore, researchers discovered that the stress on the San Andreas fault has increased to the point that an earthquake with a moment magnitude greater than 7.0 can happen.
  • According to this study, the possibility of a major earthquake may rise more quickly than scientists had previously thought.
  • According to this study, the Palm Springs-Indio metropolitan area, other cities in San Bernardino, Riverside, and Imperial counties in California, and Mexicali Municipality in Baja California would sustain significant damage in the event of a large earthquake in that southern section of the San Andreas fault. 
  • In addition to heavily populated places like Los Angeles County, Ventura County, Orange County, San Diego County, Ensenada Municipality and Tijuana Municipality, Baja California, San Luis Rio Colorado in Sonora, and Yuma, Arizona, it would be felt keenly throughout much of Southern California. 
  • Buildings constructed on unconsolidated gravel or in coastal regions with high water tables would also be particularly vulnerable to damage or collapse, as would older structures.

POSSIBLE EFFECTS OF A SAN ANDREAS QUAKE

  • The researchers calculated that such an earthquake would result in $200 billion in damage, 50,000 injuries, and 2,000 fatalities. 
  • Everything a city needs to function would be devastated, possibly taking longer than a year to fix, including the water, electricity, sewage systems, telecommunications, and roadways. 
  • Without a working infrastructure, Los Angeles’ economy might quickly collapse, and its population would relocate.
  • Because of the clogged highways and broken water supply, emergency services would be unable to put out all of the flames that ignited. Whole areas of Los Angeles would be destroyed when smaller fires combined to become larger ones. 
  • The San Andreas fault is crossed by the lines that supply water, power, and gas to Los Angeles; following the earthquake, these lines would break and would not be repaired for months. 
  • Many modern buildings might be rendered structurally unusable even if the majority survived the earthquake. Days later, the state would be shaken by aftershocks, which would intensify the devastation

San Andreas Fault Worksheets

This fantastic bundle includes everything you need to know about the San Andreas Fault across 26 in-depth pages. These ready-to-use worksheets are perfect for teaching kids about The San Andreas Fault. The San Andreas Fault is the tectonic boundary that separates the Pacific Plate and the North American Plate. It divides California in half between Cape Mendocino and the border with Mexico.

San Andreas Fault Worksheets
San Andreas Fault Worksheets
San Andreas Fault Worksheets

Download Includes the Following Worksheets

  1. San Andreas Fault
  2. The Golden State
  3. Mapping the Fault
  4. Earthquake History
  5. San Andreas Watch
  6. The “Big One”
  7. Preparing for the Quake
  8. Loma Prieta Earthquake
  9. The Specialist
  10. Types of Faulting
  11. Geologic Effects

Frequently Asked Questions

What is the San Andreas Fault?

The San Andreas Fault is a tectonic boundary between the Pacific Plate and the North American Plate that runs through California. It is one of the most well-known and active faults in the world, and is responsible for numerous earthquakes in California.

How long is the San Andreas Fault?

The San Andreas Fault is approximately 800 miles (1,290 kilometers) long, stretching from the Salton Sea in Southern California to Cape Mendocino in Northern California.

How often does the San Andreas Fault produce earthquakes?

The San Andreas Fault produces earthquakes frequently, with thousands of small earthquakes occurring along the fault each year. However, large earthquakes are less common, with the last major earthquake occurring in 1857.

What is the potential for a large earthquake on the San Andreas Fault?

Scientists predict that the San Andreas Fault has the potential to produce a large earthquake, with a magnitude of 7.0 or greater, at any time. The likelihood of a major earthquake increases as time passes since the last one.

What are the potential consequences of a large earthquake on the San Andreas Fault?

A large earthquake on the San Andreas Fault could have devastating consequences for California. The shaking could cause damage to buildings, roads, and other infrastructure and could trigger landslides and tsunamis. The economic and human toll could be significant, with the potential for loss of life, injuries, and displacement of populations.

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Use With Any Curriculum

These worksheets have been specifically designed for use with any international curriculum. You can use these worksheets as-is, or edit them using Google Slides to make them more specific to your own student ability levels and curriculum standards.

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