Gravity changes from a stress evolution earthquake simulation of California

Abstract

The gravity signal contains information regarding changes in density at all depths and can be used as a proxy for the strain accumulation in fault networks. A stress evolution time‐dependent model was used to create simulated slip histories over the San Andreas Fault network in California. Using a linear sum of the gravity signals from each fault segment in the model, via coseismic gravity Green's functions, a time‐dependent gravity model was created. The steady state gravity from the long‐term plate motion generates a signal over 5 years with magnitudes of ±∼2 μ Gal; the current limit of portable instrument observations. Moderate to large events generate signal magnitudes in the range of ∼10 to ∼80 μ Gal, well within the range of ground‐based observations. The complex fault network geometry of California significantly affects the spatial extent of the gravity signal from the three events studied.