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Another view showing polarities
Notes. A fault plane solution (or focal mechanism) determines two possible planes for the fault;
one can not determine which of the planes is the actual fault plane from this
procedure alone. The strike (0 to 360 degrees is a compass direction
that specifies the orientation
of the fault (0 degrees is N; 90=east; 180=S, 270=W, etc). Dip is the
steepness of the fault; it ranges from 0 degrees (horizontal fault) to 90 degrees
(vertical fault).Rake (0-360 degrees) is an angle, measured in the plane of the fault,
between the strike direction and the direction that the material on the upper side of the
fault moved relative to the material on the bottom side.
A strikeslip fault produces mostly horizontal motion. Reverse and Normal
faults produce dip-slip motion perpendicular to the strike
direction and have a component of vertical ground motion. For a reverse fault the material
on the upper side of the fault moves up; for a normal fault the material
on the upper side of the fault moves down.