Pre-Quaternary refers to any time before 1.6 million years ago. Some amount of reverse slip is often seen in predominantly lateral faults. If a reverse fault has a dip angle of less than 45 degrees, it is called a thrust fault. Scarps are often produced by faulting, especially that which involves a significant amount of dip slip . A segment of an active fault zone that has not experienced a major earthquake during a time interval when most other segments of the zone have.
Seismologists commonly consider seismic gaps to have a high future-earthquake potential.
A measure of the strength of an earthquake, equal to the product of the force and the moment arm of the double-couple system of forces that produces ground displacements equivalent to that produced by the actual earthquake slip. It is also equal to the product of the rigidity modulus of the Earth material, the fault surface area, and the average slip along the fault. Therefore, both seismological and geological observations can produce the same result. A region of the Earth's crust, generally linear, associated with active seismicity. It may not necessarily be connected with a particular fault or surface fault trace.