山崎断層における伸縮変化と降雨との関係について

Abstract

Records of the continuous crustal movements include many signals not only from the in-terior of the earth but also from the exterior of the solid earth. Effects of rainfall on strain varia-tion are large factors in them. The observation tunnel acrossing fractured zone of the Yamasakifault is situated at the depth of several meters under the ground surface.We have analyzed the variations of strain observed there and discussed on the nature of effectsby rainfalls. Following characteristics have been found out.(1) Large amplitude variations of strain after rainfalls are recorded in the direction ofS34°E, and small or no variations of strain after rainfalls are observed in the directionof S56°W.(2) The effects of rainfalls are observed only at the limited span in the tunnel. It showsthat strain variations by rainfalls are extremely local phenomena.Strain response are calculated by the simulation using a tank model. Some results of calcu-lation are shown.