A consequence of the dilatancy/fluid-diffusion mechanism for shallow earthquakes is that considerable volumes of fluid are rapidly redistributed in the crust following seismic faulting. This is borne out by the outpourings of warm groundwater which have been observed along fault traces following some moderate (M5–M7) earthquakes. The quantities of fluid involved are such that significant hydrothermal mineralisation may result from each seismically induced fluid pulse, and the mechanism provides an explanation for the textures of hydrothermal vein deposits associated with ancient faults, which almost invariably indicate that mineralisation was episodic.
- Received June 16, 1975.
- Revision received July 23, 1975.
- © Geological Society of London 1975