鹿野・吉岡断層周辺におけるガンマー線測定 (II)

Abstract

The observation of γ-ray intensity has been done on and near the Shikano and Yoshiokafaults once a month since June, 1981. On the other hand, fundamental observations havebeen carried on at a standard point near the Tottori Microearthquake Observatory.Continuous observation of γ-ray intensity was carried out for successive 2 days at thestandard point, and an interesting phenomenon was observed. Namely, the γ-ray intensityincreased suddenly, continuing for about 5 minutes in the rain, and restored to the normalvalue again.Pattern of temporal change of γ-ray intensity is considered nearly the same amongseveral observation regions in a period of one and a half years since June, 1981.A decreasing of intensity was observed at nearly the same time in July, 1982 in manyobservation regions. More detailed investigation is necessary, however, in order to determinewhether this decreasing is significant or not, and, if so, whether it is related to the earth-quake occurrence or not.