Abstract: Through comparison of dry model and w et model, the roles of groundwater in the process of time-space evolution of seismic precursor stress field before the earthquake are studied by means of three dimensional modeling. The results show that the presence of groundwater will not only enhance the rheological property of the time-space evolution of precursor stress field, make the stress concentrate on the fault zones, but improve enhance the fracture level, especially at the short-imminent stag e, it often becomes remarkable. However, as the depth goes deeper, the mechanical effects of groundwater on the distribution of stress field drops gradually.

Key words: Groundwater, The time-space evolution of precursor stress fields, Three dimensional numerical modeling