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 low [S.sub.mf] and [V.sub.f] values obtained for the Sierra Alhamilla southern front (Sa, Sc and Se in figure 6, values are shown in table 1) support the recent to present activity of the NW-SE- to NNW-SSE-striking high-angle normal fault system that affects the southern slope of the ridge and the Almeria-Nijar basin.
The map picture of the Pstrazna area shows two uplifted blocks separated by normal faults. The first block is constituted by E-W-elongated zone of Carboniferous exposure, the other one by Kudowa Massif (KM) in the southeast.
In order to resolve this ambiguity five geoelectrical profiles were measured and interpreted in the area of presumed normal faults.
(2002), based on earlier ideas exposed by Arthaud and Matte (1977) and Menard and Molnar (1988), relates the origin and evolution of these basins to a dominant extensional tectonic regime in the interior of the Iberian microplate along NW-SE normal faults and N-S associated sinistral strike-slip faults as an intraplate tectonic response to the stress at the southern and northern margins of the microplate during the lithosphaeric collapse of the roots of the Variscan Orogen, starting immediately after the end of the Variscan compressive stress regime at the end of the Carboniferous, that is, a precursor extensional tectonic regime of the generalised Alpine extension developed from Late Permian times onwards in the Iberian microplate.
and Xu, B.: 2017, Numerical analysis of the effects induced by normal faults and dip angles on rock bursts.
A total of 7 fault dip angles are considered; 3 angles of the normal fault are defined as [beta] = 45[degrees], [beta] = 60[degrees], and [beta] = 75[degrees], and 4 angles of the reverse fault are defined as [beta] = 45[degrees], [beta] = 60[degrees], [beta] = 75[degrees], and [beta] = 90[degrees].
A normal fault was studied at Selwicks Bay, striking ENE-WSW, and dipping steeply (N70[degrees]) to the NNW.
Xie, "Features of coal bumps influenced by normal faults in coal mining with hard roof and hard coal," Chinese Journal of Rock Mechanics and Engineering, vol.
Ziarat Pir Fault is a normal fault lying immediately west of the Kalabagh Fault.
Some of the normal faults suffered strike slip movements during part of their history.
This defined the geometry of a large tilted fault block closed by a major normal fault. Detailed geophysical and geological studies were completed in 1999.
This depressed zone lies between the bounding normal fault and rim zone, an uplifted area that surrounds the inner crater.