Long-range Static Directional Stress Transfer in a Cracked, Nonlinear Elastic Crust

G. Ouillon; D. Sornette

doi:10.1016/j.future.2005.04.007

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arXiv · physics/0304054

Long-range Static Directional Stress Transfer in a Cracked, Nonlinear Elastic Crust

G. Ouillon·D. Sornette

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Abstract

Seeing the Earth crust as crisscrossed by faults filled with fluid at close to lithostatic pressures, we develop a model in which its elastic modulii are different in net tension versus compression. In constrast with standard nonlinear effects, this ``threshold nonlinearity'' is non-perturbative and occurs for infinitesimal perturbations around the lithostatic pressure taken as the reference. For a given earthquake source, such nonlinear elasticity is shown to (i) rotate, widen or narrow the different lobes of stress transfer, (ii) to modify the $1/r^2$ 2D-decay of elastic stress Green functions into the generalized power law $1/r^γ$ where $γ$ depends on the azimuth and on the amplitude of the modulii asymmetry. Using reasonable estimates, this implies an enhancement of the range of interaction between earthquakes by a factor up to 5-10 at distances of several tens of rupture length. This may explain certain long-range earthquake triggering and hydrological anomalies in wells and suggest to revisit the standard stress transfer calculations which use linear elasticity. We also show that the standard double-couple of forces representing an earthquake source leads to an opening of the corresponding fault plane, which suggests a mechanism for the non-zero isotropic component of the seismic moment tensor observed for some events.

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BibTeX RIS

G. Ouillon, D. Sornette. 2003-10-13. Long-range Static Directional Stress Transfer in a Cracked, Nonlinear Elastic Crust. https://doi.org/10.1016/j.future.2005.04.007

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