A general method for calculating co-seismic gravity changes in complex fault systems

A general method for calculating the total, dilatational, and free-air gravity for fault systems with arbitrary geometry, slip motion, and number of fault segments is presented. The technique uses a Greenʹs function approach for a fault buried within an elastic half-space with an underlying driver plate forcing the system. The method is easily adapted to investigate a wide range of geophysical applications and is provided as a suite of Fortran90 routines. The Joshua Tree-Landers-Hector Mine sequence is examined and shows remarkable correlation of epicentres with dilatational gravity highs. We also demonstrate the use of the method for large thrusting events, using the Alaska Good Friday earthquake of 1964 as an example.