Seismic magnitude scales by tectonic forces. When this stress becomes great enough to rupture the crust, or to overcome the friction that prevents one block of crust from slipping past another, energy is released, some of it in the form of various kinds of seismic waves that cause ground-shaking, or quaking. "Magnitude" is an estimate of the relative "size" or strength of an "earthquake", and thus its potential for causing ground-shaking. It is "approximately related to the released seismic energy." "Intensity" refers to the strength or force of "shaking" at a given location, and can be related to the peak ground velocity. With
Seismic anisotropy Seismic anisotropy Seismic anisotropy is a term used in seismology to describe the directional dependence of the velocity of seismic waves in a medium (rock) within the Earth. A material is said to be anisotropic if the value of one or more of its properties varies with direction. Anisotropy differs from the property called heterogeneity in that anisotropy is the variation in values with direction at a point while heterogeneity is the variation in values between two or more points. Seismic Anisotropy can be defined as the dependence of seismic velocity on direction or upon angle. General anisotropy is described