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Transient stress-coupling between the 1992 Landers and 1999 Hector Mine, California, earthquakes

Bulletin of the Seismological Society of America

By:
and
DOI: 10.1785/0120000905

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Abstract

A three-dimensiona l finite-element model (FEM) of the Mojave block region in southern California is constructed to investigate transient stress-coupling between the 1992 Landers and 1999 Hector Mine earthquakes. The FEM simulates a poroelastic upper-crust layer coupled to a viscoelastic lower-crust layer, which is decoupled from the upper mantle. FEM predictions of the transient mechanical behavior of the crust are constrained by global positioning system (GPS) data, interferometric synthetic aperture radar (InSAR) images, fluid-pressure data from water wells, and the dislocation source of the 1999 Hector Mine earthquake. Two time-dependent parameters, hydraulic diffusivity of the upper crust and viscosity of the lower crust, are calibrated to 10-2 m2.sec-1 and 5 ?? 1018 Pa.sec respectively. The hydraulic diffusivity is relatively insensitive to heterogeneous fault-zone permeability specifications and fluid-flow boundary conditions along the elastic free-surface at the top of the problem domain. The calibrated FEM is used to predict the evolution of Coulomb stress during the interval separating the 1992 Landers and 1999 Hector Mine earthquakes. The predicted change in Coulomb stress near the hypocenter of the Hector Mine earthquake increases from 0.02 to 0.05 MPa during the 7-yr interval separating the two events. This increase is primarily attributed to the recovery of decreased excess fluid pressure from the 1992 Landers coseismic (undrained) strain field. Coulomb stress predictions are insensitive to small variations of fault-plane dip and hypocentral depth estimations of the Hector Mine rupture.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Transient stress-coupling between the 1992 Landers and 1999 Hector Mine, California, earthquakes
Series title:
Bulletin of the Seismological Society of America
DOI:
10.1785/0120000905
Volume
92
Issue:
4
Year Published:
2002
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Bulletin of the Seismological Society of America
First page:
1470
Last page:
1486