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.
Strike is always at a right angle to dip .
The breakage of ground along the surface trace of a fault caused by the intersection of the fault surface area ruptured in an earthquake with the Earth's surface. The intersection of a fault plane with the surface of the Earth. Because of its shearing motion, it cannot propagate through liquids. In this age of modern seismic data-recording networks, this translates to more than 100 km from the nearest operational station in that network. A specific kind of reverse fault in which the dip of the fault is less than 45 degrees over much if not all of its length.