An implosive component in the seismic moment tensor of a mining-Induced tremor

In early 1988, a special study in one of the major South African gold fields yielded seismograms that indicate seismic moment tensors having substantial implosive components. The moment tensor, resulting from the inversion of the ground motion data from the best-recorded event, was decomposed into isotropic and deviatoric components from which both the coseismic volumetric closure ΔV and the total shear deformation AD, where A is fault area and D is average slip, could be estimated. The finding here that ΔV ∼ AD is consistent with earlier analyses of how the tabular mine stopes interact with the surrounding rock mass to produce seismic deformation.