Field Site Investigation: Effect of Mine Seismicity on Groundwater Hydrology

摘要

The results of a field investigation on the groundwater-hydrologic effect of mining-induced earthquakes are presented. The investigation was conducted at the Lucky Friday Mine Idaho; the groundwater pressure in three fracture zones was monitored over a 24-mo period. The magnitude, source location, and associated ground motions of mining-induced seismic events were also monitored. Several seismic events of magnitude 1.0 or larger were recorded, many of which caused a change in the groundwater pressure. The magnitude of groundwater-pressure change varied with the seismic-event magnitude and source distance. The data was examined using regression analysis. The statistical models obtained predicted the effects of small-magnitude seismic events more satisfactorily than those of larger ones. The observed change in groundwater pressure due to seismic events of magnitude 3.0 or more were larger than those predicted using the statistical models. Based on these results, it is suggested that the effect of earthquakes on groundwater flow may be better understood through mechanistic modeling. The mechanical processes and material behavior that would need to be incorporated in such a model are examined. They include a description of the effect of stress change on the permeability and water storage capacity of a fractured rock mass; transient fluid flow; and the generation and transmission of seismic waves through the rock mass.