Acoustically induced slip in sheared granular layers: Application to dynamic earthquake triggering
Loading...
Authors
Ferdowsi, Behrooz
Griffa, Michele
Guyer, Robert A.
Johnson, Paul A.
Marone, Chris
Carmeliet, Jan
Issue Date
2015
Type
Article
Language
Keywords
dynamic earthquake triggering , induced earthquake , fault mechanics , granular mechanics of fault gouge
Alternative Title
Abstract
A fundamental mystery in earthquake physics is "how can an earthquake be triggered by distant seismic sources?" Here we use discrete element method simulations of a granular layer, during stick slip, that is subject to transient vibrational excitation to gain further insight into the physics of dynamic earthquake triggering. Using Coulomb friction law for grains interaction, we observe delayed triggering of slip in the granular gouge. We find that at a critical vibrational amplitude (strain) there is an abrupt transition from negligible time-advanced slip (clock advance) to full clock advance i.e., transient vibration and triggered slip are simultaneous. The critical strain is of order 10-6, similar to observations in the laboratory and in Earth. The transition is related to frictional weakening of the granular layer due to a dramatic decrease in coordination number and the weakening of the contact force network. Associated with this frictional weakening is a pronounced decrease in the elastic modulus of the layer. The study has important implications for mechanisms of triggered earthquakes and induced seismic events and points out the underlying processes in response of the fault gouge to dynamic transient stresses.
Description
Citation
Ferdowsi, B., Griffa, M., Guyer, R. A., Johnson, P. A., Marone, C., & Carmeliet, J. (2015). Acoustically induced slip in sheared granular layers: Application to dynamic earthquake triggering. Geophysical Research Letters, 42(22), 9750�57. doi:10.1002/2015gl066096
Publisher
License
In Copyright (All Rights Reserved)
Journal
Volume
Issue
PubMed ID
ISSN
0094-8276