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AGU: Reviews of Geophysics

 

Keywords

  • faulting
  • stress
  • focal mechanisms

Index Terms

  • Seismology: Seismicity and tectonics
  • Tectonophysics: Dynamics and mechanics of faulting
  • Tectonophysics: Rheology and friction of fault zones
  • Tectonophysics: Stresses: crust and lithosphere
  • Tectonophysics: Dynamics: seismotectonics

Abstract

REVIEWS OF GEOPHYSICS, VOL. 46, RG4001, 34 PP., 2008
doi:10.1029/2007RG000240

Seeking Anderson's faulting in seismicity: A centennial celebration

Bernard Célérier

Geosciences Montpellier, Université de Montpellier II, CNRS, Montpellier, France

The reactivation of faults with near-optimal orientations is commonly considered to control the state of stress in the crust. Near the surface, where a principal stress direction is vertical, the attitude of such faults is explained by Anderson's theory. This raises the questions of how prevalent this type of faulting actually is in current seismicity, down to what depth it frequently occurs, and what range of friction angles explains it best. The Global Centroid Moment Tensor catalog is analyzed to address these questions. Dip-slip and strike-slip mechanisms are dominant, and oblique slips are relatively rare for well-constrained events with depths shallower than 30 km. Preferred Andersonian faulting is the simplest, but not the unique, explanation for this dominance. Isolating reverse, strike-slip, and normal events reveals an asymmetry in the distribution of nodal plane dips and plunges of the P, B, and T axes between reverse and normal faulting. Assuming that the most frequent events correspond to reactivation near optimal orientations yields 40–60° and 0–20° friction angles for reverse and normal faults, respectively. This indicates that reverse and normal faulting mechanics are not symmetrical with respect to stress configuration as predicted by Anderson's theory.

Received 14 August 2007; accepted 3 April 2008; published 1 October 2008.

Citation: Célérier, B. (2008), Seeking Anderson's faulting in seismicity: A centennial celebration, Rev. Geophys., 46, RG4001, doi:10.1029/2007RG000240.

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