Analysis of ground fissures using content ratios of nuclides by car-borne survey

A new system was tested for car-borne and manual surveys of natural radiation to detect open fissures concealed in the ground. Positive deviation of the primary gamma ray dose ratio of 214Bi and 208Tl from its moving average was adopted as the main index. Localities where the positive deviation exceeded a threshold value gave a good indication of the existence of covered open fissures. The lowest of the deviations in a traverse was proportional to the amount of 222Rn ascending through fissures. This measurement system proved to be effective in prospecting for ground-water, hot springs, uranium, oil and natural gas resources and in earthquake prediction studies. (author)