Stress and fault parameters affecting fault slip magnitude and activation time during a glacial cycle

Abstract

The growing and melting of continental ice sheets during a glacial cycle is accompanied by stress changes and reactivation of faults. To better understand the relationship between stress changes, fault activation time, fault parameters, and fault slip magnitude, a new physics-based two-dimensional numerical model is used. In this study, tectonic background stress magnitudes and fault parameters are tested as well as the angle of the fault and the fault locations relative to the ice sheet. Our results show that fault slip magnitude for all faults is mainly affected by the coefficient of friction within the crust and along the fault and also by the depth of the fault tip and angle of the fault. Within a compressional stress regime, we find that steeply dipping faults (∼75°) can be activated after glacial unloading, and fault activity continues thereafter. Furthermore, our results indicate that low-angle faults (dipping at 30°) may slip up to 63 m, equivalent to an earthquake with a minimum moment magnitude of 7.0. Finally, our results imply that the crust beneath formerly glaciated regions was close to a critically stressed state, in order to enable activation of faults by small changes in stress during a glacial cycle. © 2014. American Geophysical Union. All Rights Reserved.