Moment-Tensor Inversions of Single Cast Mining Cast Blasts


Site Characterization

To facilitate the moment-tensor inversion, test-site velocity structure was constrained by a refraction survey conducted on the test bench during the experiment. Both P and S wave sources were used in the survey to directly determine the compressional and shear wave velocities. Refraction section plots are shown to the right in which the data indicate a two-layered model. Material attenuation was estimated by forward waveform modeling. We adopted a Mueller-Murphy* explosion source model and an attenuative propagation medium in the modeling and attempted to constrain the source and attenuation parameters at the same time. By grid-search, optimum parameter combination was achieved when the synthetic seismograms best fit the data.

The figures below show the comparison between the vertical ground velocity data from shot S8 and the synthetics calculated with the optimum source and path parameters. The resulting velocity model obtained from the refraction survey and the modeling is listed in the (non-clickable) table where the density was estimated from nominal values.

* Mueller, R. A. and J. R. Murphy (1971). Seismic characteristics of underground nuclear detonations part I. Seismic spectrum scaling, Bull. Seism. Soc. Am., 61, 1675-1692.

       


Introduction | Data | Site Characterization | Moment-Tensor Inversion | Discussion