Moment tensors of ten witwatersrand mine tremors
Pure and Applied Geophysics PAGEOPH
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Abstract
Ground motions, recorded both underground and on the surface in two of the South African Gold mining districts, were inverted to determine complete moment tensors for 10 mining-induced tremors in the magnitude range 1.9 to 3.3. The resulting moment tensors fall into two separate categories. Seven of the events involve substantial coseismic volumetric reduction-??V together with normal faulting entailing shear deformation ??AD, where the summation is over fault planes of area A and average slip D. For these events the ratio-??V/??AD ranges from 0.58 to 0.92, with an average value of 0.71. For the remaining three events ??V is not significantly different from zero; these events are largely double-couple sources involving normal faulting. Surprisingly, the two types of source mechanism appear to be very distinct in that there is not a continuous distribution of the source mix from ??V=0 to-??V?????AD. Presumably, the coseismic closure indicates substantial interaction between a mine stope and adjacent shear failure in the surrounding rock, under the influence of an ambient stress for which the maximum principal stress is oriented vertically. ?? 1992 Birkha??user Verlag.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Moment tensors of ten witwatersrand mine tremors |
| Series title | Pure and Applied Geophysics PAGEOPH |
| DOI | 10.1007/BF00879963 |
| Volume | 139 |
| Issue | 3-4 |
| Year Published | 1992 |
| Language | English |
| Publisher location | Birkha??user-Verlag |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Pure and Applied Geophysics PAGEOPH |
| First page | 781 |
| Last page | 800 |
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