Effect of slip-weakening distance on selected seismic source parameters of mining-induced fault-slip

Abstract

Fault-slip caused by mining activities in underground mines could cause severe damage to nearby mine openings due to seismic waves arising from the fault-slip. A better understanding of seismic source parameters, such as seismically radiated energy and the maximum slip rate, is of pivotal importance in estimating the damage induced by the fault-slip. It is widely recognized that dynamic behaviour of fault-slip is largely affected by slip-weakening behaviour. In the present study, the effect of the slip-weakening behaviour on selected seismic source parameters of fault-slip is investigated using a mine-wide numerical model encompassing a fault running parallel to an orebody. A linear slip-weakening law is employed in a parametrical study with respect to characteristic slip-weakening distance, d0, assuming two types of fault-slip: (a) zonal fault-slip taking place across the fault; (b) local fault-slip taking place within limited areas of the fault, i.e., it is assumed that fault-slip is arrested by surrounding rockmasses. Results obtained from the dynamic analysis indicate that seismically radiated energy and slip rates are significantly affected by d0 for both types of fault-slip. On the other hand, the seismic moment is susceptible to d0 only for zonal fault-slip, given that d0 is smaller than the maximum shear displacement increment during the fault-slip. These results imply that considering slip-weakening distance is critical in estimating seismically radiated energy and slip rates, whereas slip-weakening behaviour might not have a large influence on seismic moment of local fault-slip.