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Onto what planes should Coulomb stress perturbations be resolved?

Biomedical Sciences Research Institute Computer Science Research Institute Environmental Sciences Research Institute Nanotechnology & Advanced Materials Research Institute

Steacy, S, Nalbant, SS, McCloskey, J, Nostro, C, Scotti, O and Baumont, D (2005) Onto what planes should Coulomb stress perturbations be resolved? JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 110 (B5). B05S15. [Journal article]

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DOI: 10.1029/2004JB003356

Abstract

[1] Coulomb stress maps are produced by computing the tensorial stress perturbation due to an earthquake rupture and resolving this tensor onto planes of a particular orientation. It is often assumed that aftershock fault planes are ``optimally oriented''; in other words, the regional stress and coseismic stress change are used to compute the orientation of planes most likely to fail and the coseismic stress is resolved onto these orientations. This practice assumes that faults capable of sustaining aftershocks exist at all orientations, an assumption contradicted by the observation that aftershock focal mechanisms have strong preferred orientations consistent with mapped structural trends. Here we systematically investigate the best planes onto which stress should be resolved for the Landers, Hector Mine, Loma Prieta, and Northridge earthquakes by quantitatively comparing observed aftershock distributions with stress maps based on optimally oriented planes (two- and three-dimensional), main shock orientation, and regional structural trend. We find that the best model differs between different tectonic regions but that in all cases, models that incorporate the regional stress field tend to produce stress maps that best fit the observed aftershock distributions, although not all such models do so equally well. Our results suggest that when the regional stress field is poorly defined, or in structurally complex areas, the best model may be to fix the strike of the planes upon which the stress is to be resolved to that of the main shock but allow the dip and rake to vary.

Item Type:Journal article
Faculties and Schools:Faculty of Life and Health Sciences
Research Institutes and Groups:Environmental Sciences Research Institute
Environmental Sciences Research Institute > Geophysics
ID Code:137
Deposited By:Professor Sandy Steacy
Deposited On:05 Nov 2009 13:54
Last Modified:22 Jun 2011 15:03

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