The main goal of this proposal is to characterize the propagation of shock waves into porous rocks either in the presence water or under dry conditions to better understand damage produced during earthquake rupture. We propose to study how the propagation of an elastic shock wave a rock may be influenced by the presence of free water that may change phase during deformation (i.e. cavitation). To reach this goal we will use a gas gun developed on beamline ID19, which can send shock waves, and MHz X-ray imaging.