HR: 0800h
AN: S11B-0166    [Abstracts]
TI: Moment Tensor Inversions of Single-Fired Mining Explosions at a Copper Mine in Arizona
AU: * Zhou, R
EM: rzhou@smu.edu
AF: Southern Methodist University, Dept. of Geological Sciences , Dallas, TX 75275-0395 United States
AU: Stump, B W
EM: bstump@smu.edu
AF: Southern Methodist University, Dept. of Geological Sciences , Dallas, TX 75275-0395 United States
AU: Yang, X
EM: xyang@lanl.gov
AF: Los Alamos National Laboratory, EES-11, Los Alamos, NM 87545
AB: A portion of the Source Phenomenology Experiments (SPE) conducted 9 explosions at a copper mine in Arizona in 2003 with different yields, depths of burial and confinement conditions. We used a frequency-domain linear inversion technique to obtain time-dependent source moment tensors for these explosions. A detailed velocity model for the inversions was compiled from the analysis of a refraction survey conducted at the test bed; first arrivals of P-waves recorded at the stations around the mine and the inversion of Rg waves generated by these explosions. The Green's functions were calculated using the reflectivity method. The model was tested against observed data through forward waveform modeling prior to completing the inversions. The resulting moment tensors for all sources produce horizontal force couples, Mxx and Myy that are similar in amplitude and shape and an enhanced vertical force couple, Mzz. This source asymmetry is related to interaction of the explosion with the free surface and results in enhanced vertical asymmetry in the moment tensor for the shallowest shots, some of which cratered the free surface. For the three, fully-contained explosions (B4, B6 and B10) with no cratering, the maximal amplitudes of the moment tensors increase with the yield reflecting the coupling effect. Strong off-diagonal elements of the moment tensor were found for all shots with the Mxz component often the largest. This deviatoric component may reflect the fracturing of the granite in the source region. The three, twice-normal burden shots (B3, B5 and B8) all cratered resulting in large volumes of fractured granite and enhanced Mxz components that were bigger than the horizontal force couples, Mxx and Myy.
DE: 7299 General or miscellaneous
SC: Seismology [S]
MN: Fall Meeting 2005