Definition - What does Normal Fault mean?
Normal Fault is a crack that a geological rock formation generally experiences when one portion of the cracked rock moves in one direction relative to other cracked portion. In Normal type faults, when the rupture happens in the earth's crust, one side of the fault moves in the downward direction with respect to other fault side.
Petropedia explains Normal Fault
Since the outer portion of Earth is cold relative to its inner portion, it tends to break when it experiences stress. These cracks caused in the surface or in any geological rock formations form faults. There are two terminologies associated with Normal Faults:
- Hanging Wall – It is the portion of rock formed because of a crack or fault that looks like it is hanging out over the side of the other cracked portion.
- Foot Wall – It is the other part of the faulted rock portion.
In a Normal Fault, the hanging wall moves in a downward direction relative to the foot wall and the fault surface steeply dips ranging from 50 degrees to 90 degrees. Two topographies are produced from normal faults:
- Horst Topography
- Graben Topography