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Cindered coal detection using transient electromagnetic methods
125A 883172 Coal seam mapping by underground in-seam sebmle surveys Hatherly, P J
Geophysical techniques See also: 883146
Geoexploration V24, N4/5, Nov 1987, 1'285-294
883168 Use of electromagnetic induction to detect the spatial variability of the salt and clay contents of soils Williams, B G; Hocy, D
Aust J Soil Res V25, N1, 1987, P21-27 The apparent electrical conductivity of a 250ha area was mapped using an electromagnetic terrain conductivity meter. Values obtained were highly correlated with both total soluble salts and total clay particles of size less than 2 microns, to a depth of i 5m. The technique may be considered for mapping potential salinity hazards and locating areas with marked textural discontinuity within the profile.
883169 Scimflc reqmme analy~ of the foundation area of the Acbelom River Dam (Central Greece) as determined from a seismic refraction survey and the benndary-element method Tselentis, G A; Thanassoulas, C; Stavrakakis, G
Geoexpioration V24, 3t3, Oct 1987, P197-206 A detailed seismic refraction study using P and S waves was used at Acheloos dam. The results were incorporated into twodimensional boundary element analysis to solve the elastodynamic field equation for incident SH-waves from strong earthquakes. Results show a significant difference in response characteristics between two sites, increasing towards the higher frequencies. A combination of the boundary element method and geophysics could be a powerful tool to analyse the response of sites with an irregular soil profile.
883170 Macroscopic physical model for the self-potential of a sulphide
deposit
Eskola, L; Hongisto, H
Geoexpioration V24, N3, Oct 1987, P219-226 A model for the self-potential of an electric conductor in an electrolytic environment is developed mathematically, based on simple geometry. Computer simulation of a 2-d sulphide prism in a homogeneous half space is described. This shows that the shape and intensity of the self-potential anomaly depends on geometry and the primary source of formation, and is independent of the resistivity of the environment.
In-seam seismic surveys are used in Australia to identify geological anomalies. The propagation of Evison waves is described. The in-seam seismic method is unable to image reflectors at arbitrary orientations, so geophones in boreholes are used. Retreat longwall mining allows tomographic surveys of small features before mining commences. 883173 In-seam seismic detection of geological structm~ Wilson, R G
Geoexpioration V24, 314/5, Nov 1987, P295-300 Longwall mining demands improved prediction of faulting. In seam seismic methods can provide this accuracy and are widely used in 'Australia. Application of the method, the present state of technology and 2 case histories are described. 883174 Gentenmgraphy for the delineation of coal seam mlcture Rogers, P G; Edwards, S A; Young, J A; Downey, M
Geoexpioration V24, N4/5, Nov 1987, 1'301-328 Computer simulations of crosshole and offset VSP seismic surveys are used to show the problems encountered in their interpretation, especially due to incomplete and irregular data coverage. Interpretation of tomograms, the influence of constralnts on tomographic image quality and the inadequacy of first break picking in seismic tomography are discussed. 883175 Multifonction sonde for horizontal berehele logging Gladwin, M T; Rowlands, D; Leven, J
Geoexploration V24, N4/5, Nov 1987, P329-345 Research on geophysical approaches to outburst prediction has led to development of a series of geophysical sondes to detect anomalous structure in coal seams. The design of a selfcontained, multi-facility sonde, using remote communication, is described. Field tests indicate the potential of the sonde, but many modifications are necessary before it may be routinely applied. 883176 Cindered coal detection using transient electromagnetic metheds King, A
Geoexploration V24, N4/5, Nov 1987, 1'367-379 Transient electromagnetic (TEM) sounding indicates that cindered coal seams have abnormally low resistivity on sounding waves. Results from collieries in the Sydney basin correlate reasonably well with known geological sections.
883171 Location of sub-sorface geeelectric anemalies for archaealegical work: a ¢Omlmrimn between experimental arrays and interpretation using numerical metbeds Orlando, L; Piro, S; Versino, L
883177 Coal seam structure delineation by downbole-eromhole sebmk methods Hawkins, L V; Wootton, P; Holmes, W H
Geoexpioratios V24, N3, Oct 1987, P227-237
Geoexploration V24, 314/5, Nov 1987, P409-419
A resistivity survey utilised a Wenner array and 3 focused arrays to locate underground tombs. Contour maps were plotted for each array, showing that the trielectrode array identifies anomalies most clearly due to its superior penetration capacity and lower sensitivity to superficial noise. Numerical analysis was used to improve signal to noise ratio, and enabled a more meaningful interpretation of results. All t h e tombs were successfully located.
Transmission of high seismic frequencies is directly related to rock strength or elasticity. In weak rock, extreme high frequency attenuation occurs, so seismic sources and seismometers must be located below the weakened layer. An experiment using a marine sparker source and hydrophones for vertical and crosshole logging, and Yo Yo profiling is described. Current developments in multichannel data acquisition using arrays of hydrophones to improve records are discussed.
© 1988 Pergamon Press plc. Reproduction not permitted
Geophysical techniques See also: 883146
Geoexploration V24, N4/5, Nov 1987, 1'285-294
883168 Use of electromagnetic induction to detect the spatial variability of the salt and clay contents of soils Williams, B G; Hocy, D
Aust J Soil Res V25, N1, 1987, P21-27 The apparent electrical conductivity of a 250ha area was mapped using an electromagnetic terrain conductivity meter. Values obtained were highly correlated with both total soluble salts and total clay particles of size less than 2 microns, to a depth of i 5m. The technique may be considered for mapping potential salinity hazards and locating areas with marked textural discontinuity within the profile.
883169 Scimflc reqmme analy~ of the foundation area of the Acbelom River Dam (Central Greece) as determined from a seismic refraction survey and the benndary-element method Tselentis, G A; Thanassoulas, C; Stavrakakis, G
Geoexpioration V24, 3t3, Oct 1987, P197-206 A detailed seismic refraction study using P and S waves was used at Acheloos dam. The results were incorporated into twodimensional boundary element analysis to solve the elastodynamic field equation for incident SH-waves from strong earthquakes. Results show a significant difference in response characteristics between two sites, increasing towards the higher frequencies. A combination of the boundary element method and geophysics could be a powerful tool to analyse the response of sites with an irregular soil profile.
883170 Macroscopic physical model for the self-potential of a sulphide
deposit
Eskola, L; Hongisto, H
Geoexpioration V24, N3, Oct 1987, P219-226 A model for the self-potential of an electric conductor in an electrolytic environment is developed mathematically, based on simple geometry. Computer simulation of a 2-d sulphide prism in a homogeneous half space is described. This shows that the shape and intensity of the self-potential anomaly depends on geometry and the primary source of formation, and is independent of the resistivity of the environment.
In-seam seismic surveys are used in Australia to identify geological anomalies. The propagation of Evison waves is described. The in-seam seismic method is unable to image reflectors at arbitrary orientations, so geophones in boreholes are used. Retreat longwall mining allows tomographic surveys of small features before mining commences. 883173 In-seam seismic detection of geological structm~ Wilson, R G
Geoexpioration V24, 314/5, Nov 1987, P295-300 Longwall mining demands improved prediction of faulting. In seam seismic methods can provide this accuracy and are widely used in 'Australia. Application of the method, the present state of technology and 2 case histories are described. 883174 Gentenmgraphy for the delineation of coal seam mlcture Rogers, P G; Edwards, S A; Young, J A; Downey, M
Geoexpioration V24, N4/5, Nov 1987, 1'301-328 Computer simulations of crosshole and offset VSP seismic surveys are used to show the problems encountered in their interpretation, especially due to incomplete and irregular data coverage. Interpretation of tomograms, the influence of constralnts on tomographic image quality and the inadequacy of first break picking in seismic tomography are discussed. 883175 Multifonction sonde for horizontal berehele logging Gladwin, M T; Rowlands, D; Leven, J
Geoexploration V24, N4/5, Nov 1987, P329-345 Research on geophysical approaches to outburst prediction has led to development of a series of geophysical sondes to detect anomalous structure in coal seams. The design of a selfcontained, multi-facility sonde, using remote communication, is described. Field tests indicate the potential of the sonde, but many modifications are necessary before it may be routinely applied. 883176 Cindered coal detection using transient electromagnetic metheds King, A
Geoexploration V24, N4/5, Nov 1987, 1'367-379 Transient electromagnetic (TEM) sounding indicates that cindered coal seams have abnormally low resistivity on sounding waves. Results from collieries in the Sydney basin correlate reasonably well with known geological sections.
883171 Location of sub-sorface geeelectric anemalies for archaealegical work: a ¢Omlmrimn between experimental arrays and interpretation using numerical metbeds Orlando, L; Piro, S; Versino, L
883177 Coal seam structure delineation by downbole-eromhole sebmk methods Hawkins, L V; Wootton, P; Holmes, W H
Geoexpioratios V24, N3, Oct 1987, P227-237
Geoexploration V24, 314/5, Nov 1987, P409-419
A resistivity survey utilised a Wenner array and 3 focused arrays to locate underground tombs. Contour maps were plotted for each array, showing that the trielectrode array identifies anomalies most clearly due to its superior penetration capacity and lower sensitivity to superficial noise. Numerical analysis was used to improve signal to noise ratio, and enabled a more meaningful interpretation of results. All t h e tombs were successfully located.
Transmission of high seismic frequencies is directly related to rock strength or elasticity. In weak rock, extreme high frequency attenuation occurs, so seismic sources and seismometers must be located below the weakened layer. An experiment using a marine sparker source and hydrophones for vertical and crosshole logging, and Yo Yo profiling is described. Current developments in multichannel data acquisition using arrays of hydrophones to improve records are discussed.
© 1988 Pergamon Press plc. Reproduction not permitted