| Popis: |
Exploration of coal reserves at depths suitable for opencast mining in the UK may benefit from geophysical surveying techniques which can provide information on faulting and the location of old mineworkings. Shallow seismic reflection surveys have been found to be of very limited value for this application, mainly because the nature of the near-surface geology causes the reflection records to be swamped by reverberant refracted arrivals, and commonly groundroll also. Reflections have been observed on such data from interfaces below 100m, typically the maximum depth of interest for opencast mining, but it is doubtful whether such data can be of economic benefit. The technique of hole-to-surface seismic reflection surveys, making use of the boreholes drilled routinely in opencast coal exploration, clearly has much greater potential. Sections have been obtained along two lines of boreholes and show strong reflections from the thicker coal seams in the depth range 30–100m, allowing faults to be clearly imaged. |
