Intracontinental reverse-fault ruptures (magnitude, M 5.5) in the upper, seismogenic crust have dips, , that lie in the range 10–60 and are broadly compatible with expectations from laboratory measurements of rock friction. Two distinct peaks occur, at = 30 5 and = 50 5. Although the lower peak, at 30, corresponds to expected optimal orientation for frictional reactivation under horizontal compression and may be attributed to ramp failure, the peak at 50 is attributed to the compressional reactivation of inherited normal faults during positive inversion. A notable contrast with active subduction earthquakes and a data set from the Himalayan frontal thrust system is a general scarcity of low-angle thrusts with 10. Frictional-mechanics analysis of reverse-fault reactivation endorses long-standing suggestions that active thrust systems are likely to be fluid overpressured. However, such analysis emphasizes that both steeper reverse faults ( = 50 5) and very low angle thrusts ( 10) must be overpressured locally with respect to their surroundings (with P_f3) to become reactivated in preference to the formation or reactivation of more favorably oriented faults. Maximum sustainable overpressures are, however, limited to sublithostatic values by the presence of faults that are oriented at angles that are less than those required for frictional lockup (i.e., 60) in the prevailing stress field.

Dynamic processes of fluid redistribution tied to the earthquake stress cycle include upward migration of overpressured fluids through fault-valve action, especially on steeper reverse faults ( 60), and episodic to-and-fro migration of fluids, along strike, induced by mean-stress cycling coupled with strong ₂ directional permeability. Remarkable similarities between steep reverse-slip structures hosting mesozonal gold-quartz vein systems and comparable structural assemblages developed at much higher structural levels in sedimentary basins suggest that extreme valving action (involving redistribution of large volumes of overpressured fluids) may also play a role in hydrocarbon migration, especially in regions undergoing positive tectonic inversion.