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 interferometry location. Seismic interferometry can virtually move a source into a downhole location to better illuminate and capture steeply dipping sediments on the flank of a salt dome. In this case, the SI result was very similar to that obtained using an actual downhole source. Seismic interferometry can locate the position of an unknown source and is often utilized in hydrofrac applications to map the extent of induced fractures. It is possible that interferometric techniques can be applied to timelapse seismic monitoring of subtle changes in reservoir properties in the subsurface. Seismic interferometry applications are currently limited by a number of