Reverse and thrust faults also occur in other settings where the crust is being compressed, such as the Transverse Mountain Ranges, just north of Los Angeles. In fact, subduction zones are sometimes referred to as mega-thrust faults. A convergent plate boundary is a zone of major reverse and thrust faults. Reverse and thrust faults form in sections of the crust that are undergoing compression. The difference between a reverse fault and a thrust fault is that a reverse fault has a steeper dip, more than 30°. Hanging wall moves down with respect to footwall Typically dip about 60 degrees. In a reverse or thrust fault, the hanging wall has moved up relative to the footwall. Normal faults also occur in other zones of crustal tension, such as in the Basin and Range landscape region of the western United States. A divergent plate boundary is a zone of large normal faults. Normal and detachment faults form in sections of the crust that are undergoing tension, places where the crust is being stretched apart. Detachment faults occur along the boundaries of metamorphic core complexes (see below). It separates rocks that were deep in the crust and ductile (granite and gneiss) from rocks of the upper crust (sedimentary or volcanic) that were brittle. In a normal fault, the hanging wall has moved down relative to the footwall.Ī detachment fault is a particular kind of normal fault that generally dips at a low angle. The rocks beneath a fault are called the footwall.You can see in the illustration that the movement is. The rocks above a fault are called the hanging wall. The rocky blocks on either side of strike-slip faults, on the other hand, scrape along side-by-side.If a fault is not vertical, there are rocks above the fault and rocks beneath the fault. The rocks on either side of a fault have shifted in opposite directions, called the offset directions. Faults are caused by elastic strain that culminates in brittle failure. A fault is a planar surface within the earth, along which rocks have broken and slid.
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