Time ? A Key Seismic Source Parameter

There are five independent seismic source parameters: seismic energy, seismic moment, source size, location, and time. These parameters are investigated primarily for evaluating seismic hazard and understanding seismic source mechanism(s). Broadly, seismic hazard is the likelihood of occurrence of an event of a given magnitude. Seismic source mechanism is the mode of rockmass failure that causes the seismic event. Most mine seismicity analysis techniques use a combination of a few of the independent source parameters. In literature, time is perhaps the least discussed and most underutilized of these five parameters. This paper discusses three applications of time to understand both seismic hazard and seismic source mechanism in mines. The first application is time history analyses, which focuses on how other parameters of interest vary over time. Examples are presented to show how time history analyses can give information about both seismic hazard and seismic source mechanism. The second application is analysis of time-between-events. This technique can give insight into seismic source mechanism. The final application is phasor analysis using the Schuster test. This method can be used to investigate how seismic source mechanisms may change over time. For both time-between-events analysis and phasor analysis, there are important implications with regards to scale dependence and the breakdown of self-similarity of mining-induced seismicity.