Hydrological impact of earthquakes on reverse and normal faults: results from numerical models

Earthquakes typically induce changes in fluid pressures and fluid flow in the crust surrounding ruptured faults. However, these perturbations can result from a range of different mechanisms, which complicates interpretation of observations and hinders our understanding of how fluids interact with faults over earthquake cycles. Here I investigate earthquake-related hydrological signals of various different mechanisms - i.e., static elastic strain, thermal pressurisation, inelastic dilation on a fault and rupture of an overpressured reservoir at depth - using a two dimensional plane strain model that simulates ruptures on reverse and faults governed by rate-and-state friction that are coupled to poroelastic deformation and fluid flow along with spatio-temporal evolution of temperature and permeability. Results show that all of these mechanisms may induce significant fluid pressure perturbations and fluid redistribution in and around ruptured faults but that they operate to varying degrees at different depths and positions relative to a fault and in different tectonic regimes. Although the fluid pressure fields are quite sensitive to the driving mechanism, they may be difficult to distinguish due to (1) strong spatial gradients between a fault and the adjacent crust and (2) elevated permeabilities close to the surface that dampen the signals. Overall, the results suggest that is may be difficult to infer the role of fluids in earthquakes based on sparse observations from the surface.This results of this study are soon to be submitted to the Journal of Geophysical Research - solid Earth.The numerical results provided in this data repository consist of the solid velocity (2 components), stress tensor, fluid overpressure and temperature at each time step through time. A Matlab script is provided to enable users to plot these variables in time and space.