Loading rates in California inferred from aftershocks
- 1Laboratoire de Dynamique des Fluides Géologiques, Institut de Physique du Globe de Paris, 75252 Paris Cedex 05, France
- 2International Institute of Earthquake Prediction Theory and Mathematical Geophysics, Warshavskoye shosse, 79, korp 2, Moscow 113556, Russia
- 3Institutes of Applied and Industrial Mathematics, Universität Potsdam, P.O. Box 601553, 14115 Potsdam, Germany
Abstract. We estimate the loading rate in southern California and the change in stress induced by a transient slip event across the San Andreas fault (SAF) system in central California, using a model of static fatigue. We analyze temporal properties of aftershocks in order to determine the time delay before the onset of the power law aftershock decay rate. In creep-slip and stick-slip zones, we show that the rate of change of this delay is related to seismic and aseismic deformation across the SAF system. Furthermore, we show that this rate of change is proportional to the deficit of slip rate along the SAF. This new relationship between geodetic and seismological data is in good agreement with predictions from a Limited Power Law model in which the evolution of the duration of a linear aftershock decay rate over short time results from variations in the load of the brittle upper crust.