Post-seismic and interseismic fault creep I: model description
We present a model of localized, aseismic fault creep during the full interseismic period, including both transient and steady fault creep, in response to a sequence of imposed coseismic slip events and tectonic loading. We consider the behaviour of models with linear viscous, non-linear viscous, rate-dependent friction, and rate- and state-dependent friction fault rheologies. Both the transient post-seismic creep and the pattern of steady interseismic creep rates surrounding asperities depend on recent coseismic slip and fault rheologies. In these models, post-seismic fault creep is manifest as pulses of elevated creep rates that propagate from the coseismic slip, these pulses feature sharper fronts and are longer lived in models with rate-state friction compared to other models. With small characteristic slip distances in rate-state friction models, interseismic creep is similar to that in models with rate-dependent friction faults, except for the earliest periods of post-seismic creep. Our model can be used to constrain fault rheologies from geodetic observations in cases where the coseismic slip history is relatively well known. When only considering surface deformation over a short period of time, there are strong trade-offs between fault rheology and the details of the imposed coseismic slip. Geodetic observations over longer times following an earthquake will reduce these trade-offs, while simultaneous modelling of interseismic and post-seismic observations provide the strongest constraints on fault rheologies.
Additional Information© 2010 The Authors. Journal compilation © 2010 RAS. Accepted 2010 January 13. Received 2009 October 8; in original form 2009 March 22. We thank the editor, M. Cocco, and L. Montesi, and J. Loveless for comments and suggestions. We gratefully acknowledge discussions with J.-P. Avouac, N. Lapusta, and R. Kanda. All calculations were done using Matlab, The Mathworks Inc. This research was supported in part by the Gordon and Betty Moore Foundation. This is Caltech Tectonic Observatory contribution #116 and Caltech Seismological Laboratory contribution #10,032.
Published - Hetland2010p7471Geophys_J_Int.pdf