Normal Fault


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normal fault

[′nȯr·məl ′fȯlt]
(geology)
A fault, usually of 45-90°, in which the hanging wall appears to have shifted downward in relation to the footwall. Also known as gravity fault; normal slip fault; slump fault.

Normal Fault

 

a fracture-type tectonic displacement of rocks. In a normal fault, the relative displacement of rocks occurs either vertically or along a steeply inclined fracture in such a way that the rocks of the hanging wall are shifted downward and the rocks of the footwall move upward. Normal faults often occur in pairs, forming depressions called grabens or elevations called horsts. Step faults are also common. Normal faults form primarily under conditions of tension. Some normal faults have amplitudes of 4 and 5 km.

References in periodicals archive ?
The original dip of the faults is uncertain, but they probably dipped at up to about 45% much like most seismically active normal faults presently observed at the axes of mid-ocean ridges.
Normal fault quakes have the opposite geometry, which weakens the tremors.
Inferences about the amount of displacement of the two normal faults are of considerable interest.
The basalt flows and sedimentary strata on Grand Manan are generally within a few degrees of horizontal, but with limited areas of wide gentle folds and a few normal faults.
The normal fault extends up through the entire Devonian section and also contributes to a one-well four-way structural closure at the Wabamun level, the second target zone at the proposed location.
Re-evaluation of the seismic and geology is necessary to check the closed mechanism against the normal fault.
Fault clearance not identified by normal fault management methods -- Identification of specific network problems such as poor handover performance -- Carrier to Interference (C/I) matrices -- Recommended changes to cell neighbor lists to ensure appropriate cell handovers -- Recommended changes to BTS power output and antenna tilts -- Recommend frequency planning for fixed, broadcast control channel, and hopping carriers About Motorola
1987) formed initially as strike-slip faults, later re-activated as normal faults.
The Gulf's structure is dominated by en-echelon normal faults delimiting three elongated basins (Ben-Avraham et al.
The plateau is divided in to distinct domains or prospects by a series of normal faults.
Using a model known as Coulomb stress triggering, Lin and his colleagues found measureable increases in stress along faults to the north at Sanriku-Hokobu, south at Off Boso and at the Outer Trench Slope normal faults east of the quake's epicenter off the Japan coast near the city of Sendai.
Using a model known as Coulomb stress triggering, Lin and his colleagues found measurable increases in stress along faults to the north at Sanriku-Hokobu, south at Off Boso and at the Outer Trench Slope normal faults east of the quake's epicentre off the Japan coast near the city of Sendai.