Inversion of stresses from polyphase fault/slip data with high or low diversity: An updated version of INVSFS

Fault/slip data with low diversity show limited range in orientation, and their equations, according to the Wallace-Bott hypothesis often give rise to an unstable stress solution. It is necessary in this case to introduce some auxiliary constraint(s), so as to make a stable stress solution from these equations. A new method for inverting stress from polyphase fault/slip data with low diversity but having all or a majority of newly formed faults in each subset is developed in this paper. It combines a weak criterion that favors the newly formed faults, together with the Wallace-Bott hypothesis or the strong criterion. Both criteria are solved for stresses using the Fuzzy C-lines clustering analysis technique. This permits the updating of the INVSFS code (Li et al., 2005). Two artificial sets of polyphase fault/slip data with high and low diversity are chosen to demonstrate the performance of the updated version.