The accurate simulation of induced seismicity is crucial in estimating its risk and evaluating the damage caused by seismic waves. To achieve this, two important mechanical parameters that dictate the severity and magnitude of induced seismicity need to be determined, which are the coefficient of kinetic friction and critical slip-weakening distance. The slip-weakening distance is known to be scale-dependent. The present study proposes a methodology to take into account the scale-dependency by considering seismic efficiency in the dynamic modelling of induced seismicity.
Induced seismicity is the dynamic phenomenon of the rockmass at great depths caused by various human activities, such as underground mining, geothermal energy development, the construction of hydraulic power plant, CO2 sequestration, and so o°n (Ortlepp, 2000, Baisch et al., 2010, Majer et al., 2007, Rutqvist et al., 2007). In underground mines, a severe seismic event can produce devastating damage to mine openings (Ortlepp and Stacey, 1994), whilst for the seismic activity due to geothermal fluid injection, it may raise public concern (Majer et al., 2007). Hence, a better understanding of the mechanism of induced seismicity and developing a methodology to predict its severity are of paramount importance.
Over the past few decades, various studies have been undertaken, based on numerical analyses, field measurements, and laboratory experiments (Sainoki and Mitri, 2014, Hedley, 1992, Hu, 2011). Laboratory experiments are conducted to elucidate the fundamental mechanism of crack initiation and its propagation that could eventually lead to the failure of rockmass and seismic events (Li et al., 2004, Lockner et al., 1991), while field measurements with seismic monitoring system aim to obtain knowledge on when and where it occurs in relation to orebody extraction, fluid injection, and hydraulic fracturing (Cai et al., 2001, Urbancic and Trifu, 2000, Trifu and Urbancic, 1996). Then, the numerical simulation of induced seismicity can be performed in conjunction with the aforementioned approaches in order to quantitatively estimate the magnitude of a seismic event (Sjöberg et al., 2012) and/or back-analyze the mechanical properties of the causative fault (Hofmann and Scheepers, 2011, Sainoki and Mitri, 2 016 ).