Stress loading from viscous flow in the lower crust and triggering of aftershocks following the 1994 Northridge, California, earthquake
Geophysical Research Letters
By: J. Deng, K. Hudnut, M. Gurnis, and E. Hauksson
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Abstract
Following the M(w) 6.7 Northridge earthquake, significant postseismic displacements were resolved with GPS. Using a three-dimensional viscoelastic model, we suggest that this deformation is mainly driven by viscous flow in the lower crust. Such flow can transfer stress to the upper crust and load the rupture zone of the main shock at a decaying rate. Most aftershocks within the rupture zone, especially those that occurred after the first several weeks of the main shock, may have been triggered by continuous stress loading from viscous flow. The long-term decay time of aftershocks (about 2 years) approximately matches the decay of viscoelastic loading, and thus is controlled by the viscosity of the lower crust. Our model provides a physical interpretation of the observed correlation between aftershock decay rate and surface heat flow.Following the Mw 6.7 Northridge earthquake, significant postseismic displacements were resolved with GPS. Using a three-dimensional viscoelastic model, we suggest that this deformation is mainly driven by viscous flow in the lower crust. Such flow can transfer stress to the upper crust and load the rupture zone of the main shock at a decaying rate. Most aftershocks within the rupture zone, especially those that occurred after the first several weeks of the main shock, may have been triggered by continuous stress loading from viscous flow. The long-term decay time of aftershocks (about 2 years) approximately matches the decay of viscoelastic loading, and thus is controlled by the viscosity of the lower crust. Our model provides a physical interpretation of the observed correlation between aftershock decay rate and surface heat flow.
Suggested Citation
Deng, J., Hudnut, K., Gurnis, M., and Hauksson, E., 1999, Stress loading from viscous flow in the lower crust and triggering of aftershocks following the 1994 Northridge, California, earthquake: Geophysical Research Letters, v. 26, no. 21, p. 3209-3212, https://doi.org/10.1029/1999GL010496.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Stress loading from viscous flow in the lower crust and triggering of aftershocks following the 1994 Northridge, California, earthquake |
| Series title | Geophysical Research Letters |
| DOI | 10.1029/1999GL010496 |
| Volume | 26 |
| Issue | 21 |
| Year Published | 1999 |
| Language | English |
| Publisher | American Geophysical Union |
| Publisher location | Washington, DC, United States |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Geophysical Research Letters |
| First page | 3209 |
| Last page | 3212 |