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Topic: Normal fault

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	Geologic fault - Wikipedia, the free encyclopedia
		Faults are the source of many earthquakes that are caused by slippage vertically or laterally along the fault.
		Faults can be categorized into three groups: normal faults, transform (or strike-slip) faults and reverse (or thrust) faults.
		A special class of strike-slip faults are the transform faults which are a plate tectonics feature related to spreading centers such as mid-ocean ridges.
	en.wikipedia.org /wiki/Geologic_fault (447 words)

	FAULT - LoveToKnow Article on FAULT (Site not responding. Last check: 2007-10-21)
		Faults are to be distinguished from joints and fissures by the fact that there must have been a movement of the rock on one side of the fault-plane relatively to that on the other side.
		Normal faults are regarded as the result 2f stretching of the crust, hence they have been called tension faults as distinguished from reversed faults, which are assumed to be due to pressure.
		Faults crossing folded strata cause the outcrops to approach on the upthrow side of a syncline and tend to separate the outcrops of an antidine (figs.
	16.1911encyclopedia.org /F/FA/FAULT.htm (2546 words)

	Thrust fault - Open Encyclopedia (Site not responding. Last check: 2007-10-21)
		A thrust fault is a particular type of fault, or break in the fabric of the Earth's crust with resulting movement of each side against the other, in which one side is pushed up relative to the other and somewhat over it.
		A normal fault is similar but results from tension or extensional forces with the upper side dropping down relative to the lower.
		If the angle of the fault plane is low (generally less than 20 degrees from the horizontal) and the displacement of the overlying block is large (often in the kilometer range) the fault is called an overthrust.
	open-encyclopedia.com /Thrust_fault (178 words)

	Geologic fault -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-10-21)
		Faults are the source of many (Shaking and vibration at the surface of the earth resulting from underground movement along a fault plane of from volcanic activity) earthquakes that are caused by slippage vertically or laterally along the fault.
		Faults can be categorized into three groups: normal faults, (Click link for more info and facts about transform (or strike-slip) faults) transform (or strike-slip) faults and (Click link for more info and facts about reverse (or thrust) faults) reverse (or thrust) faults.
		A ridge between two parallel normal faults is called a (A ridge of the earth's crust that has been forced upward between two faults and so is higher than the surrounding land) horst.
	www.absoluteastronomy.com /encyclopedia/g/ge/geologic_fault.htm (487 words)

	normal fault : Definition from the Online Dictionary at Datasegment.com
		When this plane is vertical, the fault is a vertical fault; when its inclination is such that the present relative position of the two masses could have been produced by the sliding down, along the fault plane, of the mass on its upper side, the fault is a normal fault, or gravity fault.
		When the fault plane is so inclined that the mass on its upper side has moved up relatively, the fault is then called a reverse fault (or reversed fault), thrust fault, or overthrust fault.
		The linear extent of the dislocation measured on the fault plane and in the direction of movement is the displacement; the vertical displacement is the throw; the horizontal displacement is the heave.
	onlinedictionary.datasegment.com /word/normal+fault (616 words)

	Seismology/ Geology Glossary (Site not responding. Last check: 2007-10-21)
		Fault movement (slip) that is parallel to the dip of the fault.
		A fault characterized by predominantly vertical displacement in which the hanging wall is moved downward with respect to the footwall of the fault.
		A fault in which the displacement is predominantly vertical, and the hanging wall is moved upward with respect to the footwall.
	www.scecdc.scec.org /glossary.html (2544 words)

	Oilfield Glossary: Term 'fault'
		A growth fault is a type of normal fault that forms during sedimentation and typically has thicker strata on the downthrown hanging wall than the footwall.
		A strike-slip fault in which the block across the fault moves to the right is described as a dextral strike-slip fault.
		Some fault surfaces contain relatively coarse rubble that can act as a conduit for migrating oil or gas, whereas the surfaces of other faults are smeared with impermeable clays or broken grains that can act as a fault seal.
	www.glossary.oilfield.slb.com /Display.cfm?Term=fault (428 words)

	Todd Ehlers: Geothermal Research (Site not responding. Last check: 2007-10-21)
		Research Synopsis: The thermal regime across an active normal fault is complicated by tectonic processes of uplift and erosion of the foot-wall side of the fault and burial and sedimentation on the hanging-wall.
		The thermal state across an active normal fault is complicated by "hot" material being uplifted on the foot-wall side of the fault, and "cold material" advected into the subsurface on the hanging-wall.
		The thermal regime of a fault zone is important for estimating rock rheology and strength of rocks, nucleation and propagation of earthquake ruptures, the brittle ductile transition and chemical reactions that seal fractures.
	www.gps.caltech.edu /~ehlers/home/msthesis.html (1173 words)

	Photo Glossary of Earthquakes
		A fault is a fracture along which the blocks of crust on either side have moved relative to one another parallel to the fracture.
		Strike-slip faults are vertical (or nearly vertical) fractures where the blocks have mostly moved horizontally.
		A thrust fault is a reverse fault with a dip of 45° or less.
	earthquake.usgs.gov /image_glossary/fault.html (168 words)

	EFFECT OF GRAVITY ON NORMAL FAULT PROFILES ON MARS VERSUS EARTH (Site not responding. Last check: 2007-10-21)
		The shape of normal faults on Earth is recognized as a key factor in determining the location and shape of basins and mountain ranges, sedimentation patterns in active fault systems, patterns of earthquake seismicity, and pathways for flow and accumulation of fluids.
		Extensional fault scarps on Mars and Earth have many similarities, including the morphology and segmentation of fault scarps, and their map-view arrangement, while lines of topographic depressions (pit chains) that are parallel or collinear with extensional faults are apparently unique to Mars.
		In the normal faulting regime, maximum principal effective stress is primarily a function of rock density, depth, and gravity.
	gsa.confex.com /gsa/2002AM/finalprogram/abstract_41199.htm (501 words)

	Normal Faults
		There are three normal faults in the pink tuffs to the right of the welded tuff.
		Normal faults often occur in pairs, with one being the main fault and the other being a smaller conjuagate fault.
		Given the angle of the fault, the upper red line is on the footwall, the lower red line is on the hanging wall.
	www.pitt.edu /~cejones/GeoImages/7Structures/NormalFaults.html (441 words)

	fault on Encyclopedia.com
		Movement along a fault plane may be vertical, horizontal, or oblique in direction, or it may consist in the rotation of one or both of the fault blocks, with most movements associated with mountain building and plate tectonics.
		In dip-slip faults the term “hanging wall” is used for the side that lies vertically above the other, called the “footwall.” A fault in which the hanging wall moves down and the footwall is stationary is called a normal fault.
		Faults create interpretation problems for geologists by altering the relations of strata (see stratification), such as making the same rock layer offset in two vertical cross sections of a formation or making layers disappear altogether.
	www.encyclopedia.com /html/f1/fault.asp (1038 words)

	Notes on Chapter 5: Normal Faults (p
		Separation and Normal Faulting The appearance of normal faulting as repeated or missing stratigraphic sections depends on the angle of the bedding to the fault and displacement.
		Local Normal Faults Associated with Other Structures Normal faults are generally associated with structures that require extension of the crust, such as salt domes, folds, cavities, and pull-apart structures on strike-slip faults.
		Because normal faulting increases the distance between two points on opposite sides of the fault, the fault extends and thins in order to maintain a constant cross-sectional area.
	www.seismo.berkeley.edu /~burgmann/EPS116/summaries/wk3summ.html (726 words)

	[No title]
		That fault and parallel structures are excellent candidates for the fault that slipped in at least two of the earthquakes studied.
		Hence, normal faults dipping 30 are likely to be seismically active in at least one part of this rift system.
		Because shallow dips for normal faults are seen near the rift tip, but not elsewhere along strike, high strain rates may be an important factor in allowing normal faults to slip at unusually shallow dips.
	www.agu.org /pubs/abs/jb/97JB00787/97JB00787.html (359 words)

	Normal Fault Populations/NEGSA 2000 (Site not responding. Last check: 2007-10-21)
		Fault size in continental settings is widely considered or assumed to follow a power-law distribution, but few studies have demonstrated self-similar distributions over a large scale range.
		Fault populations in experimental models of oblique extension show mainly exponential distributions, possibly because the oblique rift zone limits the maximum length of faults.
		Fault populations exhibit both spatial clustering and anticlustering related to stress enhancement and reduction zones, respectively, surrounding normal faults.
	www.rci.rutgers.edu /~schlisch/negsarws2000.html (328 words)

	[No title]
		A low-angle normal fault emerges along the northern flank of Moresby Seamount, a continental crustal block with green-schist metamorphic basement.
		The growing evidence for a weak fault and strong crust associated with motion on the San Andreas transform fault supports the weak normal detachment fault model, and models abound in the literature in which low-angle detachment faulting is an essential mechanism of large-scale strain accommodation.
		North of Moresby Seamount, a low-angle normal fault dips north beneath a down-flexed pre-rift sedimentary basin and basement sequence, unconformably onlapped by synrift sediments that are cut by higher angle normal faults with a zig-zag pattern in plan view (Figs.
	www-odp.tamu.edu /publications/tnotes/tn20-5/180.txt (4957 words)

	Faults.html
		The normal fault is not necessarily normal in the sense that it is common....because....
		In a normal fault the two involved blocks are (by gravity) pulling away from one another causing one of the fault blocks to slip upward and the other downward with respect to the fault plane (it is hard to determine whether both or just one block has moved.).
		The dip angles of thrust faults are normally not as steep as a normal fault.
	www.tinynet.com /faults.html (808 words)

	Kattenhorn, S.A., Pollard, D.D., and Aydin, A. (1997) (Site not responding. Last check: 2007-10-21)
		This addition of frictional behavior is important because the manner in which a normal fault slips affects both its subsequent evolution in terms of propagation tendency, and deformation in the region around the slipping fault.
		A field example where joints are related to normal faulting in Arches National Park, Utah, demonstrates the range in possible orientations of joints that form in the perturbed stress field of a normal fault.
		Slip gradients are greatest towards the upper extent of the fault tipline, and differ from predicted slip distributions on frictionless normal faults.
	www.webpages.uidaho.edu /~simkat/gsa97.html (359 words)

	SHALLOW-ANGLE MORESBY NORMAL FAULT (Site not responding. Last check: 2007-10-21)
		Fault weakening as a consequence of (a) the high slip rates (the 30- to 37-mm/yr extension is focused on the Moresby rift, as the seismicity shows) and (b) the talc-chlorite-serpentine gouge mineralogy and
		These fault properties and failure modes are a logical consequence of a continent with an ophiolitic upper crust being rapidly extended adjacent to a seafloor spreading center.
		Such shallow-angle normal faults may be a common feature of strain localization during the transition from rifting to spreading (Abers et al., 1997; Taylor et al., 1999; Floyd et al., 2001; Pérez-Gussinyé and Reston, 2001).
	www.ga.gov.au /odp/publications/180_SR/synth/synth_11.htm (1135 words)

	fault
		A fault in which the hanging wall is the upthrown side is called a thrust fault because the hanging wall appears to have been pushed up over the footwall.
		Such faults are formed by compressional forces that push rock together and are by far the most common of the dip-slip faults.
		All types of faults have been recognized on the ocean floor: normal faults occur in the rift valleys associated with mid ocean ridges spreading at slow rates; strike-slip faults appear between the offset portions of mid-ocean ridges; and thrust faults occur at subducting plate boundaries.
	www.infoplease.com /ce6/sci/A0818338.html (479 words)

	Along-strike Segmentation of Pliocene-Recent Normal Fault Systems, Eastern Offshore Trinidad (Site not responding. Last check: 2007-10-21)
		In the southern area adjacent to the Orinoco delta of Venezuela and north of the Venezuela-Trinidad boundary, a master normal fault is seaward-dipping, listric, and associated with toe thrusts in the deepwater area.
		In the central area north of the Trinidad-Venezuela border and south of the Darien ridge, the master normal fault is landward-dipping and slightly oblique to the NS trend of the slope.
		Antithetic faults dip seaward and form the edges of a prominent, 5-km-wide, “keystone” rift and overlying slope channel that focuses sand and debris flows from the shelf into the deeper water area.
	aapg.confex.com /aapg/da2004/techprogram/A88078.htm (314 words)

	Mark Anders: Research
		Faults were formed on a 738 ka surface formed by the Bishop Tuff (Figure from Dawers and Anders, 1995).
		In order for scaling relationships between fault length and displacement to be maintained during linkage, displacement must be accelerated in the linkage region to account for the increased length of the fault.
		The displacement on these faults when summed results in a pattern for the total fault system that is roughly representative of the displacement pattern of each of the smaller faults.
	www.ldeo.columbia.edu /~manders/research.html (2900 words)

	e-Prints Soton - Normal fault growth and linkage during the last 1.3 million years: an example from the Whakatane ... (Site not responding. Last check: 2007-10-21)
		Determination of fault growth rates and fault network evolution at timescales from 104 to 106 years has been hampered by a lack of a well-constrained stratigraphic succession that provides a high-fidelity record of fault development over these time periods.
		Initially, the dominant process of fault growth was tip propagation, with an average and maximum displacement rates of 0.52 ± 0.18 and 0.72 ± 0.23 mm yr−1, respectively.
		Following fault segment linkages, the average displacement rate of the fault network increased by almost threefold to 1.41 ± 0.31 mm yr−1, while the maximum displacement rate increased to 3.4 ± 0.2 mm yr−1.
	eprints.soton.ac.uk /9876 (397 words)

	Shallow Dip on the 1954 Dixie Valley Fault
		A global study by Jackson (1987) shows a similar limit (approximately 35 degrees) on normal fault dip and reveals that faults are essentially planar and dip steeply down to the brittle-ductile transition.
		Given planar faults and minimum fault dip of 38 degrees, simple geometric relations (Jackson and McKenzie, 1983) can be used to show that the maximum extension possible from a single fault system with rotation of dip is 40%.
		The 30-degree dipping fault plane is clear, as are the sub-parallel foliations in the granite below, and sub-horizontal alluvial layers in the headwall.
	www.seismo.unr.edu /ftp/pub/louie/talks/sci-wlgtn/dixie.html (2027 words)

	Progressive Localisation (Site not responding. Last check: 2007-10-21)
		The initial stage of fault system evolution was characterised by rapid growth in fault length in the first 1-2Ma of extension.
		During the third stage, shortening of the traces of active faults and high mortality rates for small faults, resulted in a net decrease in fault trace length on successively younger horizons.
		Fault throw populations have constant slopes on each syn-faulting horizon, however an up-sequence shallowing of the slope of length and geometric moment populations demonstrates a progressive concentration of strain onto fewer and larger faults through time.
	www.fault-analysis-group.ucd.ie /Publications/66Meyer.html (262 words)

	Low-Angle Normal Fault
		Along with low-angle normal faults, this domain is segmented by intense high-angle faulting of variable orientation and displacement.
		The Low-Angle Normal Fault Domain is well displayed across a broad eastern portion of the evaluation area east of a line which marks the easternmost limit of Golconda and Roberts Mountains thrusting.
		It is important to realize that these low-angle normal faults form in complexes of multiple faults that merge with or cut one another, and exhibit upper plates with numerous, imbricate high-angle listric normal faults with small to relatively large displacements and brecciation.
	www.westerncordillera.com /low-angle_normal_fault.htm (820 words)

	Fault System Polarity (Site not responding. Last check: 2007-10-21)
		Abstract - The evolution of normal fault populations and their synthetic and antithetic sub-populations has been studied for a number of fault systems imaged from seismic reflection data.
		Relationships between fault strain and polarity and the slope of fault throw populations have been investigated by backstripping a fault system in the Inner Moray Firth, North Sea, and by comparison between throw populations for pre-faulting horizons from an additional 11 fault systems with variable extensional strains.
		Fault population slopes decrease with increasing strain reflecting strain localisation onto progressively fewer and larger faults.
	www.fault-analysis-group.ucd.ie /Publications/88Polarity.html (238 words)

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