A system and method to predict rock strength by directly inverting for petrophysical properties. In one embodiment, seismic data is received or obtained from a seismic survey (step 101). The seismic data are then conditioned (step 103) in order to prepare them for an inversion process (step 105). The inversion process has an embedded rock physics model that allows the inversion to be formulated based upon, and thereby outputting or calculating (step 107), petrophysical properties. Rock strength data may then be calculated from the petrophysical properties (step 109).
