Studies of roadway modes in a coal seam by dispersion and polarization analysis: a case history
P. Krajewski, L. Dresen, W. Schott and H. Rüter
Journal name: Geophysical Prospecting
Issue: Vol 35, No 7, September 1987 pp. 767 - 786
Info: Article, PDF ( 1.32Mb )
Field data from two-component in-seam seismic measurements are used to study roadway modes and their interaction with reflected seam waves. Using the multiple-filter technique to investigate the dispersion behaviour of the different waves, it can be shown that the roadway modes disperse very similarly to the related transmitted seam waves. However, because of the free surface of the coal face, the dispersion curves of the roadway modes show a velocity reduction and a slight shift to lower frequencies compared to those of the related transmitted seam waves. Polarization analysis using hodograms, rectilinearity and polarization angle confirms these results. The parameters found by polarization analysis can be used to design polarization filters which help to separate roadway modes and reflected events in the traveltime range of superposition in the presented field case.