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Teper, L. & A. Lisek (2006). Analysis of displacement geometry: A tool for identifying kinematic type of fault. Publs. Inst. Geophys. Pol. Acad. Sc. M-29 (395), 119-130.
Tectonic motion along fault is the basic cause of mining induced tremor. Determining focal mechanism of tremor produced by slip on a fault is ineffective with regard to slip direction until rock volume is identified reliably. An orthogonal projection of fault onto the vertical plane containing strike of the fault surface seems to be the technique, which can provide information appropriate to help with answering the question about the focal mechanism. Introduced projection enables three-dimensional geometry of fault to be illustrated constructing contour displacement diagrams and calculating displacement gradients over fault surface. This paper describes displacement distribution along selected well-identified faults from the central part of the Upper Silesian Coal Basin. Using contour displacement diagrams we have calculated displacement gradients, drawing attention to the existence of four distinct types of pattern. The different patterns are related to different orientations of principal axes that characterise fault growth. Examining the gradient data patterns one can determine direction and sense of actual slip on the fault surface. Information brought by displacement geometry analysis, supplemented with ellipticity study and shear moduli calculation, enables kinematic types of faults to be identified. Strike-slip faults, oblique-slip faults, and dip-slip faults can be recognised by means of presented method. Similarly, left-handed faults can be distinguished from right-handed ones. Procedure presented enables measurements and observation of faults made by mine surveyors to be directly used in seismological interpretations for identifying fault plane responsible for mine tremor occurrence.