Fault Types

Faults are subdivided using the relative movement of the two blocks:

• Normal Fault

  In normal faulting, the hanging wall block moves down relative to the footwall block. The fault plane usually makes a high angle with the surface (> 45 degrees). Normal faults are associated with crustal tension.
  

• Reverse Fault

  In reverse faulting, the hanging wall block moves up relative to the footwall block. The fault plane usually makes a low angle with the surface (< 45 degrees). Reverse faults are associated with crustal compression and are also known as thrust faults.
  

• Strike-slip Fault

  In strike-slip faulting, the two blocks move either to the left (sinistral ) or to the right (dextral) relative to one another. Strike-slip faults are associated with crustal shear and are also known as wrench faults.