Relation between effective friction and fault slip rate across the Northern San Andreas fault system
Ann-Sophie Provost, Jean Chéry, 2006. "Relation between effective friction and fault slip rate across the Northern San Andreas fault system", Analogue and Numerical Modelling of Crustal-Scale Processes, S. J. H. Buiter, G. Schreurs
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The San Andreas Fault system is a complex tectonic ensemble that accommodates most of the relative plate motion between the Pacific and the North American plates. The structure and rheological properties of the faults vary along the plate boundary and lead to the distribution of deformation that we observe today. In order to learn more about the mechanical behaviour of such a fault system, a model of the northern California fault system is built, constrained by heat flow data, GPS and palaeoseismological measurements of slip rates (on the San Andreas, the Maacama and Bartlett Springfaults), and stress orientations. Our basic assumption is that the upper crust has a high frictional strength and that major faults represent weak zones with a lower effective friction. Several combinations of effective fault frictions on the three major faults of the system in the model are tested. We find that slight variations of the effective friction angle on one of the three active strands lead to an important redistribution of slip rates through the system. If present in nature, this fault behaviour could explain why fault slip rates vary in time, as suggested by slip rate variations over geological scales in intracontinental fault systems.
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The crust of the Earth records the deformational processes of the inner Earth and the influence of the overlying atmosphere. The state of the Earth’s crust at any time is therefore the result of internal and external processes, which occur on different time and spatial scales. In recent years important steps forward in the understanding of such complex processes have been made by integrating theory and observations with experimental and computer models. This volume presents state-of-the-art analogue and numerical models of processes that alter the Earth’s crust. It shows the application of models in a broad range of geological problems with careful documentation of the modelling approach used. This volume contains contributions on analogue and numerical sandbox models, models of orogenic processes, models of sedimentary basins, models of surface processes and deformation, and models of faults and fluid flow.