| Abstract: | High Frequency Mining Seismics. Reflection profiles in mining galleries have been made with a new type of equipment including appropriate arrays, special geophones and high frequency recording (30–2000 c.p.s.). Reflections at frequencies between 600 and 1200 c.p.s. have been obtained, in favourable cases, from coal beds about 3 feet thick, lying at depths reaching 200 feet below the gallery. Good rock compactness is necessary to obtain fair reflections, and in such cases it may be possible to detect discontinuities in the coal beds. |
