A method for conducting an earth reservoir process includes receiving a stress field of a reservoir that includes a pore pressure field for a rock volume, selecting a search radius extending from a grid cell of interest, and substituting a pore pressure from a plurality of surrounding grid cells within the selected radius for the pore pressure of the grid cell of interest and determining if a critical stress state exists for each of the substituted pore pressures. The method further includes determining a shortest distance to a grid cell in the plurality of surrounding grid cells having a pore pressure that yields a critical stress state when substituted in the grid cell of interest and conducting the earth reservoir process with earth reservoir process apparatus using a parameter related to the determined shortest distance.