鳥取市南部の吉岡地震断層系におけるγ線測定

Abstract

The Yoshioka fault was associated with the Tottori Earhtquake occurred in 1943 at thesouthern part of the Tottori prefecture, Southwest Japan. This fault was researched byTsuya (1944) and by Kurokawa (1982), nevertheless, the location and strike of the fault is obscure inand around the Nosaka area, because of the thick sedimentary.Therefore, we attempt to pursue the r-ray surveys for the search of the fault in and aroundthe Nosaka area where we measured the r-ray intensity at 61 points. We took notice of thecomplicated feature of the geological constituents on the surface of the earth around the Nosakaarea. Then, the values of r-ray intensity observed are the total values of those, 1. The values of r-ray intensity at the surface of the earth, 2. The values of the r-ray intensity derived from the geological components of the widesurface of the earth, 3. And the values origined of the cosmic rays.The influences from 2. And 3. Are small and constant, then they have been neglected. Thereforewe adopted the values which were subtracted the values caused of 2.and 3.from the values of thetotal ones measured at 1.Considering of the maps of contours of the r-ray intensities, the strong place of the r-rayintensity was just on the fault inferred by Kurokawa (1982) in the Nosaka area.