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Faults

A fault line is created when there is a shift in the Earth, like an earthquake. It is a fracture or a break in the ground. There are three main types of fault lines. Let’s learn more!
Road cracked from erosion

A cracked road used as an example of a fault line.

What are the Different Types of Fault Lines?

There are three main types of fault lines: Normal, strike-slip, and thrust. These are caused by different forces that push and pull the earth up and down and even side to side. 
  1. Normal – These faults pull apart, creating space. They can create a special type of valley called a rift valley. Two examples of this are the Sawtooth Fault in Idaho and the Moab Valley in Utah. 
  2. Strike-Slipe – These faults happen when two tectonic plates slide past each other with little to no vertical movement. Two examples of this are the San Andreas Fault in California and the Alpine Fault in New Zealand.
  3. Thrust (Reverse) – These faults create mountains. They happen when two tectonic plates slide on top of each other and push themselves up. Two examples of this are the Rocky Mountains in Utah and the Kern Canyon in the Sierra Nevada Mountain Range
Fault line diagram.

Visual description of types of fault lines.

What is the San Andreas Fault?

The San Andreas Fault is a strike-slip fault line about 750 miles long in California. That’s as far as a trip from Utah to Washington! This fault slips at a rate of almost 2 inches per year and is due for a big earthquake soon.
 

Sign for the San Andreas Fault Line

Photo taken at San Andreas

 
Scientists say that this is because there is stress on the tectonic plates. They will slip because of this stress. While dangerous, this is pretty common around large transform boundaries.

Why are Earthquakes More common near Fault Lines?

As we’ve learned, fault lines are created when there is movement in the Earth. This is caused by stress put on tectonic plates, which cause earthquakes. They can be big or small. 80% of earthquakes happen in a place called the Pacific Ring of Fire. The main reason for this is because the California coast sits right above two tectonic plates that make up the Earth’s crust.

Map of the tectonic plates across the world.

An example of tectonic plate boundaries.

Other Great Resources: 

San Andreas Fault – SimpleWikipedia – https://simple.wikipedia.org/wiki/San_Andreas_Fault
 
Fault Lines: Facts About Cracks in the Earth – LiveScience – https://www.livescience.com/37052-types-of-faults.html
 
Moab Fault – Wikipedia – https://en.wikipedia.org/wiki/Moab_Fault
Written by: Hannah Bertoch.