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Geologic faults or simply faults are planar rock fractures which show evidence of relative movement. Large faults within the Earth's crust are the result of shear motion and active fault zones are the causal locations of most earthquakes. Earthquakes are caused by energy release during rapid slippage along faults. The largest examples are at tectonic plate boundaries, but many faults occur far from active plate boundaries. Since faults usually do not consist of a single, clean fracture, the term fault zone is used when referring to the zone of complex deformation associated with the fault plane. Appalachian geologic fault Image copyleft: Image taken by me, released under GFDL Pollinator 05:52, Sep 19, 2004 (UTC) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...
Map Location in Pennsylvania Political Statistics Founded c. ...
A rainy day in the Great Smoky Mountains, Western North Carolina The Appalachian Mountains (French: les Appalaches) are a vast system of North American mountains, partly in Canada, but mostly in the United States, forming a zone, from 100 to 300 miles wide, running from Newfoundland and Labrador, Canada, 1...
Earth cutaway from core to exosphere. ...
Global earthquake epicenters, 1963–1998. ...
The tectonic plates of the world were mapped in the second half of the 20th century. ...
The two sides of a fault are called the hanging wall and footwall. By definition, the hanging wall occurs above the fault and the footwall occurs below the fault.
Slip, heave, throw
The sense of slip is defined by the relative movements of geological features present on either side of the fault plane and is a vector. The sense of slip defines the type of fault. This is distinct from the throw of the fault, which is the vertical offset. Heave is the measured horizontal offset of the fault.
Fault types Faults can be categorized into three groups based on the sense of slip. A fault where the main sense of movement (or slip) on the fault plane is vertical is known as a dip-slip fault. Where the main sense of slip is horizontal the fault is known as a transform (or strike-slip) fault. Oblique-slip faults have significant components of both strike and dip slip. A transform fault is a geological fault that is a special case of strike-slip faulting which terminates abruptly, at both ends, at a major transverse geological feature. ...
Strike and dip refer to the orientation or attitude of a geologic feature. ...
For all naming distinctions, it is the orientation of the net dip and sense of slip of the fault which must be considered, and not the present day orientation, which may have been altered by local or regional folding or tilting.
A fold in Slichowice nature reserve in Kielce (Variscan orogeny) The term fold is used in geology when one or a stack of originally flat and planar surfaces, such as sedimentary strata, are bent or curved as a result of plastic (i. ...
Dip-slip faults Dip-slip faults include both normal and reverse. PNG of original gif from http://earthquake. ...
The United States Geological Survey (USGS) is a scientific agency of the United States government. ...
A normal fault occurs when the crust is in extension. The hanging wall moves downwards relative to the footwall. The depressed ground between two parallel normal faults is called a graben. An upthrown block between two parallel normal faults is called a horst. Low-angle normal faults with regional tectonic significance may be designated detachment faults. USGS image A graben is a depressed block of land bordered by parallel faults. ...
USGS image In physical geography and geology, a horst is the raised fault block bounded by normal faults. ...
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A reverse fault is the opposite of a normal fault - the hanging wall moves up relative to the footwall. Reverse faults are indicative of shortening of the crust. The dip of a reverse fault is relatively steep, greater than 45°.
A thrust fault has the same sense of motion as a reverse fault, but with the dip of the fault plane at less than 45°. Thrust faults typically form ramps, flats and fault-bend (hanging wall and foot wall) folds. Thrust faults are responsible for forming nappes and klippen in the large thrust belts. A thrust fault is a particular type of fault, or break in the fabric of the Earths crust with resulting movement of each side against the other, in which a lower stratigraphic position is pushed up and over another. ...
A fold in Slichowice nature reserve in Kielce (Variscan orogeny) The term fold is used in geology when one or a stack of originally flat and planar surfaces, such as sedimentary strata, are bent or curved as a result of plastic (i. ...
A nappe, in geology, is a large sheetlike body of rock that has been moved far from its original position. ...
A klippe is a geological feature of thrust fault terranes, where a nappe has thrust exotic strata over an area and been removed to leave a form of inlier. ...
The fault plane is the plane that represents the fracture surface of a fault. Flat segments of thrust fault planes are known as flats, and inclined sections of the thrust are known as ramps. Typically thrust faults move within formations by forming flats, and climb up section with ramps. Two intersecting planes in R3 In mathematics, a plane is a fundamental two-dimensional object. ...
Fault-bend folds are formed by faults from the pressure of the hangingwall and footwall moving against one another.
- diagrams explaining thrust fault geometries
In the image below, you see a normal fault at left. A reverse fault is the same, except the hanging wall moves up instead of down. At right, you see a thrust fault.
 Schematic illustration of normal and reverse faults. Note that the view is a cross-section through the Earth, such that the up-direction on the page is away from the centre of the Earth. Normal and reverse fault illustration. ...
Strike-slip faults The fault surface is usually near vertical and the footwall moves either left or right or laterally with very small vertical motion. Strike-slip faults with left-lateral motion are also known as sinistral faults. Those with right-lateral motion are also known as dextral faults. A special class of strike-slip faults is the transform faults which are a plate tectonics feature related to spreading centers such as mid-ocean ridges. A sinistral is a horizontal movement of blocks either side of a geological fault. ...
A dextral is a horizontal movement of blocks either side of a geological fault. ...
A transform fault is a geological fault that is a special case of strike-slip faulting which terminates abruptly, at both ends, at a major transverse geological feature. ...
Plate tectonics (from the Greek word for one who constructs and destroys, τεκτων, tektÅn) is a theory of geology developed to explain the phenomenon of continental drift and is currently the theory accepted by the vast majority of scientists working in this area. ...
A mid-ocean ridge or mid-oceanic ridge is an underwater mountain range, formed by plate tectonics. ...
 Schematic illustration of the two strike-slip fault types. The view is of the Earth's surface as from space. Schematic of strike-slip faults File links The following pages link to this file: Geologic fault Categories: GFDL images ...
Oblique-slip faults A fault which has a component of dip-slip and a component of strike-slip is termed an 'oblique-slip fault'. Nearly all faults will have some component of both dip-slip and strike-slip, so defining a fault as oblique requires both dip and strike components to be measurable and significant. Most oblique faults occur within transtensional and transpressional regimes. Study of geological shear is related to the study of structural geology, rock microstructure or rock texture and fault mechanics. ...
Study of geological shear is related to the study of structural geology, rock microstructure or rock texture and fault mechanics. ...
See also In plate tectonics, a transform boundary (also known as transform fault boundary, transform plate boundary, transform plate margin or conservative plate boundary) is said to occur when tectonic plates slide and grind against each other along a transform fault. ...
A duplex is a both a package of rock and a type structure. ...
An element of rock under stress Fault mechanics is a field of study that investigates the behavior of geologic faults. ...
Study of geological shear is related to the study of structural geology, rock microstructure or rock texture and fault mechanics. ...
The Allegheny Plateau is a large, dissected plateau area in southern New York, western Pennsylvania, West Virginia, and eastern Ohio. ...
References - McKnight, Tom L; Hess, Darrel (2000). “The Internal Processes: Types of Faults”, Physical Geography: A Landscape Appreciation, pp. 416-7, Upper Saddle River, NJ: Prentice Hall. ISBN 0-13-020263-0.
- Davis, George H.; Reynolds, Stephen J. (1996). “Folds”, Structural Geology of Rocks and Regions, pp. 372-424, New York, John Wiley & Sons. ISBN 0-471-52621-5.
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