Fault scarp

Source: Wikipedia, the free encyclopedia.
An eroded fault scarp from the Gobi Desert of Mongolia (left) and at Borah Peak in Idaho. The latter fault scarp (white line at the base of the tan hills) was formed in the 1983 Borah Peak earthquake

A fault scarp is a small step-like offset of the ground surface in which one side of a fault has shifted vertically in relation to the other.[1][2] The topographic expression of fault scarps results from the differential erosion of rocks of contrasting resistance and the displacement of land surface by movement along the fault.[3][4] Differential movement and erosion may occur either along older inactive geologic faults, or recent active faults.[5][6][7]

Characteristics

See also: Escarpment

Fault scarps often involve zones of highly fractured rock and discontinuities of hard and weak consistencies of rock. Bluffs can form from upthrown blocks and can be very steep, as in the case of Pakistan's coastal cliffs.

strike-slip faults.[11] Vertical displacement of ten meters may occur in fault scarps in volcanic bedrock, but is usually the result of multiple episodic movements of 5 to 10 meters per tectonic event.[12][13]

This fault scarp was created by the 1959 Hebgen Lake earthquake. Photo taken August 19, 1959.

Due to the dramatic uplift along the fault, which exposes its surface, the fault scarp is very prone to erosion. This is especially true if the material being uplifted consists of unconsolidated sediment.[14] Weathering, mass wasting, and water runoff can soon wear down these bluffs, sometimes resulting in V-shaped valleys along runoff channels. Adjacent V-shaped valley formations give the remaining fault spurs a very triangular shape. This formation is known as a triangular facet; however, this landform is not limited to fault scarps.[15]

Fault scarps may vary in size from a few centimeters to many meters.[16] Fault-line scarps are typically formed due to the differential erosion of weaker rocks along a fault. Such erosion, occurring over long time periods, may shift a physical cliff far from the actual fault location, which may be buried beneath a talus, alluvial fan or filled-in valley sediments. It may therefore be difficult to distinguish between fault scarps and fault-line scarps.[17]

Examples

References

  1. ISBN 978-0393932386
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  2. ^ "Faults" (PDF). ETH Zurich. 2020.
  3. ISBN 978-0-13-860958-0
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  5. ISBN 978-1-86239-114-7
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  6. ISBN 978-81-89422-01-1
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  7. ISBN 9781550173628
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  8. ISBN 978-1-118-68812-0
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  9. ISBN 978-0-08-091998-0
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  10. ^ Hilley, George E. (2000). Thrust Fault Slip Rates Deduced from Coupled Geomorphic and Tectonic Models of Active Faults and Folds in the San Francisco Bay Area: Collaborative Research with Arizona State University and University of California, Davis. Department of Geology, Arizona State University.
  11. doi:10.1130/GES00594.1
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  12. ^ Strahler, Arthur N. (1960). Physical Geography (2nd ed.). New York: John Wiley & Sons, Inc. p. 475.
  13. ^ Proceedings of the Workshop on Paleoseismology, 18-22 September 1994, Marshall, California. United States Geological Survey. 1994. p. 174.
  14. PMID 36890169
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  15. doi:10.1016/j.pce.2013.04.005
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  16. ^ Ramelli, Alan. "Prominent Fault Scarps in Western Nevada". Nevada Geology. Retrieved 13 May 2024.
  17. ISBN 978-1-86239-249-6. {{cite book}}: ISBN / Date incompatibility (help
    )
  18. ^ Byrd, J.O.D., Smith, R.B., Geissman, J.W. (1994) The Teton fault, Wyoming: Topographic signature, neotectonics, and mechanisms of deformation, Journal of Geophysical Research (99), No. B10, p. 20095-20122
  19. ISBN 978-0-8248-3817-1
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  20. doi:10.1130/0016-7606(1989)101<0885:TDOTWB>2.3.CO;2
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  21. ISBN 978-0-8137-2494-2
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  22. doi:10.1023/A:1011419408419
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  23. ^ "SCARP: Investigating the Malta Escarpment". University of Malta. Retrieved 2025-01-12.
  24. doi:10.1016/j.geomorph.2018.11.012
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