Focal mechanism

A fault plane solution is used in geophysics representation of the measurements of Erdbebenmesstationen respect to a particular earthquake. The fault plane solution is to better understand the underlying mechanism of an earthquake and helps in identifying the cause of the earthquake.

Representation

The representation of the fault plane solution required by each participating station both the quake associated azimuth and the respective incidence angle and the direction of vibration of the first use of the measured wave ( compression or dilatation). These data are plotted in a circle: from the North point of the circle, a solder is like down to the center. From this Lot from the azimuth of each station is taken as the angular distance and the angle of incidence as length clockwise. At the end of the resulting range, the type of wave is marked by a plus or minus, see also the sketch.

If this is done for several stations, so that discrete areas occur on the circle, the chart provides information on the cause of the earthquake, that is, whether it is deferment, deportation or transform fault.

The following gallery shows the ideal fault plane solutions of the three possible causes. Black, positively marked areas denote stations which have a measured compression.

Fault plane solution of a Aufschiebungsbebens

Fault plane solution of a shift quake