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• Print publication year: 2011
• Online publication date: June 2012

# 12 - Field analysis of faults

## Summary

Aims

Faults are measured in a very similar way as extension fractures. The main aims of this chapter are to:

Give field examples of typical faults.

Illustrate how the most important field measurements of faults are made.

Provide typical field data on dip-slip faults.

Provide field data on strike-slip faults.

Explain and discuss oblique-slip faults.

Dip-slip faults

Dip-slip faults are those where the displacement is parallel with the dip of the fault (Fig. 12.1). They include normal faults, reverse faults, and thrust faults (Figs. 8.3 and 8.8). The block above the fault plane is the hanging wall, the block below the fault plane the footwall (Fig. 12.1). Depending on the sense of slip and the fault dip, the main types of dip-slip faults are normal faults, reverse faults, thrusts, and overthrusts. More specifically, when the hanging wall moves down relative to the footwall, the fault is a normal fault. When the hanging wall moves up relative to the footwall, the fault is a reverse fault.

When the dip of a fault is less than 45° it is referred to as a low-angle fault. A low-angle normal fault is just referred to as such, but sometimes as a lag fault. However, low-angle reverse faults have special names. In general, if the dip of the reverse fault is less than 45° (for some the angle should be 30°), it is referred to as a thrust or a thrust fault.

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and , 1997. Rock Stress and its Measurements. New York: Chapman &amp; Hall.
, 1984. Tectonic analysis of fault slip data sets. Journal of Geophysical Research, 89, 5835–5848.
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and , 2002. Behaviour of a rupture of the 21 June 2000 earthquake in South Iceland as revealed in asphalted car park. Journal of Structural Geology, 24, 1925–1936.
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and , 2003. Mechanical behaviour of the Arnes and Hestfjall Faults of the June 2000 earthquakes in Southern Iceland: inferences from surface traces and tectonic model. Journal of Structural Geology, 25, 1507–1523.
, , and , 1995. Fault growth by segment linkage: an explanation for scatterin maximum displacement and trace length data from the Canyonlands Grabens of SE Utah. Journal of Structural Geology, 17, 1319–1326.
and , 1996. A modern regression approach to determining fault displacement-length scaling relationships. Journal of Structural Geology, 18, 147–152.
and , 1992. Displacement-length scaling relationships for faults: Data synthesis and discussion. Journal of Structural Geology, 14, 1149–1156.
and , 1996. Structural Geology of Rocks and Regions, 2nd edn. New York: Wiley.
, , and , 1993. Growth of normal faults: displacement-length scaling. Geology, 21, 1107–1110.
, 2007. Infrastructure and evolution of ocean-ridge discontinuities in Iceland. Journal of Geodynamics, 43, 6–29.
and , 1975. Theoretical basis of some empirical relations in seismology. Bulletin of the Seismological Society of America, 65, 1073–1095.
, 1981. Earthquake Mechanics. New York: Cambridge University Press.
and , 1995. Tectonics. New York: W.H. Freeman.
, , , and , 1996. The shapes, major axis orientations and displacement pattern of fault surfaces. Journal of Structural Geology, 18, 235–248.
, 1997. Foundation of Structural Geology, 3rd edn. London: Routledge.
, , , , and , 2003. Fault slip distribution of two June 2000 Mw 6.4 earthquakes in South Iceland estimated from joint inversion of InSAR and GPS measurements. Earth and Planetary Science Letters, 213, 487–502.
and , 1987. Theoretical displacements and stresses near fractures in rock: with applications to faults, joints, veins, dikes and solution surfaces. In: (ed.), Fracture Mechanics of Rock. London: Academic Press, pp. 277–349.
and , 2005. Fundamentals of Structural Geology. Cambridge: Cambridge University Press.
and , 1990. Analysis of Geological Structures. Cambridge: Cambridge University Press.
, 1980. The mechanics of earthquake rupture. In: and (eds.), Physics of the Earth's Interior. Amsterdam: North Holland, pp. 555–649.
, 1985. Contoured patterns of the throw and hade of normal faults in the Coal Measures (Westphalian) of north-east Derbyshire. Proceedings of the Yorkshire Geological Society, 45, 147–161.
and , 1984. Transpression. Journal of Structural Geology, 6, 449–458.
, , , and , 1996. Geometry and scaling relations of a population of very small rift-related normal faults. Geology, 24, 683–686.
, 1990. The Mechanics of Earthquakes and Faulting. New York: Cambridge University Press.
, 1997. Displacement-length scaling for terrestrial and Martian faults: implications for Valles Marineris and shallow planetary grabens. Journal of Geophysical Research, 102, 12 009–12 015.
and , 2007. Structural Geology, 2nd edn. New York: W.H. Freeman.
and , 2004. Earth Structure, 2nd edn. London: W.W. Norton.
, , and , 1996. Three-dimensional analysis of slip distributions on normal fault arrays with consequences for fault scaling. Journal of Structural Geology, 18, 295–309.
, , and , 1997. The Geology of Earthquakes. Oxford: Oxford University Press.