Types Of Fault Lines

Three Major Types Of Faults

Faults are classified by the direction of movement between their opposing faces. These movements can occur slowly and continuously or in large sudden shifts that can deform or rupture the land surface. Either way it’s the direction of these movements that characterise the actual fault types and we’ll try to cover these below.

• Dip Slip Faults - These are faults where the major movement is vertical.
• Strike Slip Faults - These are faults where the major movement is horizontal.
• Oblique Faults - These are faults where them major movements are both horizontal and vertical.

Note that in the above we are referring to the major part of the movement as most fault lines always demonstrate some level of both vertical and horizontal movement but for definition purposes we’re really referring to the major movement of that fault. Lets continue and break the fault types down even more.

Types Of Dip Slip Faults

Within the dip slip fault category (major vertical movements at the fault line) there are two main fault types.

• Normal Fault - Here rocks on one side of the fault slump below the other side.
• Reverse Fault - Here rocks on one side of the fault get pushed up above those on the other side.
• Thrust Fault - This fault is extremely similar to the reverse fault except that it happens at lower angles causing a stacking of the rocks which ultimately leads to a thickening of the local crust.

Types Of Strike Slip Faults

Within the strike slip fault category (major horizontal movements at the fault line) there are two main fault types.

• Left Lateral Strike Slip Fault - Also known as a Sinistral fault here rocks on one side of the fault slide past each other in a horizontal movement. The left is determined by the direction of the displaced fault line. i.e. it would be on the right if you were walking towards it.
• Right Lateral Strike Slip Fault - Also known as a Dextral fault here rocks on one side of the fault slide past each other in a horizontal movement. The right is determined by the direction of the displaced fault line. i.e. it would be on the right if you were walking towards it.
• Transform Fault - This is a special type of strike slip fault because it happens to run at the bounday of a tectonic plate. Although most transform faults are found on the ocean floor, many of the more well known transform faults are on dry land. The San Andreas fault line is a classic example of a land based transform fault.