Seismic magnitude scales the amount of slip, the area of the surface ruptured or slipped, and a factor for the resistance or friction encountered. These factors can be estimated for an existing fault to determine the magnitude of past earthquakes, or what might be anticipated for the future. An earthquake's seismic moment can be estimated in various ways, which are the bases of the M, M, M, M, M, M, and M scales, all subtypes of the generic M scale. See for details. Seismic moment is considered the most objective measure of an earthquake's "size" in regard of total energy. However, it is
Seismic anisotropy of 1993-1998 . The early survey does not take into anisotropy into account, while the later survey employs the PreStack Depth Migration imaging. This PSDM was done on a commercial seismic package developed by Total. The following two plots clearly reveal the resolution improvement of the PSDM method. The top plot is a convention 3D survey without anisotropy effect. The bottom plot used PSDM method. As can be seen in the bottom plot, more small structure features are revealed due to the reduce of error and improved resolution. Seismic anisotropy relies on shear waves, shear waves carry rich information which