Specifics in the formation of substituence through in the Karvina part of the Ostrava-Karvina coalfield with the use radar interferometry

Abstract

Deep extraction of minerals is accompanied by deformations of the strata overlying extracted coal seams. Deformations of overlying layers run up to the surface where a subsidence trough gradually forms. The movement of individual surface points is curvilinear, spatial and, in relation to the time pattern, not uniform. In some cases, during the formation of a subsidence trough, temporary uplifts of the surface occur. This paper gives a particular area in which uplifts of the surface occurred when the rigid overlying strata was disturbed. The character of deformations of the overlying rocks is evaluated on the basis of a comparison of the results of the measurement of subsidence of the surface using geodetic methods with the development of mined-out areas and with their extracted thickness. For specifying the time of failure of the overlying strata, also information obtained from a system of continuous monitoring of seismic events is used. The spatial extent of the subsidence trough is identified by satellite radar interferometry (InSAR) techniques applied to TerraSAR-X images. The subsidence wave was possible to detect using a short temporal difference of 11 days between satellite radar images. This shows the potential of short-temporal high resolution InSAR for monitoring of progress of subsidence troughs. A good knowledge of extents and shape of subsidence trough formation in time allows to verify values of parameters used for prediction purposes. Application of the short temporal InSAR appears very effective for spatio-temporal studies of the current subsidence trough development and helps understanding the physical process as well as identifying deviations from the behaviour expected by models.