The validity of Es/Ep as a source parameter in mining seismology

Abstract

It is generally accepted that the ratio of energy associated with the S-wave (Es) and P-wave (Ep) is dependent on the focal mechanism (Mendecki (2013). In the mining industry, the ratio of S-wave energy to P-wave energy is regarded as an important indicator of the type of focal mechanism, with the ratio being lower for explosive sources and higher for fault slip (Cai et al 1998, Mendecki, 2013). In pure shear, the Es is considerably larger than Ep (Es/Ep > 20). For the tensile model, Sato (1978) has shown that Ep and Es are approximately equal. Gibowicz et al (1991) and Gibowicz and Kijko (1994) suggest that when Es/Ep < 10, the source mechanism involves a tensile failure component. Boatwright and Fletcher (1984) suggest pure shear to correspond with Es/Ep > 10. Hudyma and Potvin (2010) suggest that for events with Es/Ep < 3, the mechanism is non-shear. This paper investigates the Es/Ep ratio parameter and how sensitive it is to different seismic service setups. It will achieve this by investigating the consistency of the parameter for three different scenarios.