Basic Fault Types

Faults are classified by how the rocks on each side of the fault or fault blocks move past eachother. The main types of movement along a fault are sideways movements called strike-slip and up-down movements called dip-slip. Check out some Califronia faults here.

Normal Faultyemen normal fault

Normal faults are not "normal" because they are the most common, but because they tend to follow the gravitational pull of the fault blocks involved. In this type of fault the hanging wall moves down relative to the footwall (view animated normal fault). This type of movement is cause by tension as the fault blocks move away from eachother.

Some examples of normal faults are the Owens Valley and the Sierra Nevada fault zones.

thrust fault

 

Thrust Faults and Reverse Faults

Thrust faults and reverse faults are very similar in that the hanging wall moves up relative to the footwall. A difference between the two is that in a thrust faults the hanging wall move up and completely slides over and covers the footwall (view animated thrust fault). The type of stress that causes both thrust and reverse faults is compression or rocks being pushed together.

An example of a thrust fault is the Klamath Mountains in Northern California.

 

 

 

san andreas

Strike-Slip Fault

Strike-slip faults or transverse faults are caused by shear stress as two fault blocks slide horizontally past eachother (view animated strike-slip fault).

The San Andreas fault is probably the most famous strike-slip fault. It forms the boundary between the Pacific Plate to the west and the North American Plate to the east. It stretches approximately 800 miles from the Salton Sea to San Fransisco and along the Northern Coast of California.

 

ca fault

 

 

 

 

 

 

Modeling Faults Activity

Click here to view fault model. Print out the fault model, color, cut and glue it together. Then complete the activity and answer the atached questions. See if you can Identify the following faults.