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Sagan, G, L. Teper & W. M. Zuberek (1996). Tectonic Analysis of Mine Tremor Mechanisms from the Upper Silesian Coal Basin, Pure and Applied Geophysics, 147 (2), 217-238.

Abstract

Fault network of the Upper Silesian Coal Basin (USCB) is built of sets of strike-slip, oblique-slip and dip-slip faults. It is typical product of force couple which acts evenly with the parallel of latitude causing horizontal and anti-clockwise movement of rock-mass. Earlier research of focal mechanisms of mine tremors using standard fault plane solution has shown that some events are related to tectonic directions in main structural units of the USCB. An attempt was undertaken to analyse the records of mine tremors from the period 1992-1994 in the selected coalfields. The digital records of about 200 mine tremors with energy larger then 1  x  104  J (ML>1.23) were analysed with SMT software for seismic moment tensor inversion. The decomposition of seismic moment tensor of mine tremors was done into isotropic (I) part, compensated linear vector dipole (CLVD) part and double couple (DC) part. The DC part is prevalent (up to 70%) in the majority of quakes from central region of the USCB. A group of mine tremors with large I element (up to 50%) can be also observed. The spatial orientation of the fault and auxiliary planes were obtained from the computations for the seismic moment DC part. Study on DC part of seismic moment tensor made it possible for us to separate the group of events which might be admitted to have their origin in unstable energy release on surfaces of faults forming regional structural pattern. A  possible influence of the Cainozoic tectonic history of the USCB on the recent shape of stress field is discussed.

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