Broadbent, M. 1974 An application of geophysical prospecting methods to fault location in the Huntly Coalfield. [s.l.]: [s.n.]. Report / Geophysics Division 96 31 p.
Abstract: The suitability of the gravity and seismic reflection geophysical prospecting techniques for accurately laterally locating faults which cut the Waikato Coal Measures in a specific area has been investigated. The area, approximately 3 km square, is centred about 5 km from Huntly railway station on a bearing of 300 deg. The depth of burial in the area of a coal seam of interest, the Lower Kupakupa, varies between about 130 and 340 m. Bouguer gravity anomalies show only a rough correlation with the depth to this coal seam, the values being much affected by the changing thicknesses and densities of the shallow Quaternary deposits. Density estimates of 1.7 Mg/cubic m for the Quaternary deposits, and 2.34 Mg/cubic m for the underlying Landon Series Oligocene sediments were obtained by using the gravity observations. Two seismic reflectors have been detected, one of these being closely associated with the coal seams. The velocity with which seismic compressional waves travelled vertically through the Landon Series sediments was about 2.1 km/s. The resolution of the seismic method as used for this investigation, like that of the gravity method, was not adequate to reliably locate faults which displaced the coal measures vertically by about 15 m. (auth.)