Features of granite cracks in the northwestern part of the Tsuruga peninsula

Terusawa, Shuji; Shimada, Koji   

The direction of the crack in the granite may have directionality, and it appears as a topography such as a linear valley. Attempts have been made to estimate stress field from the predominant direction. We compiled the results of geological survey which was conducted near the Monju cite in 2007 to 2015, and extract the predominant direction of cracks. As a result, in the northeastern area of the survey area, the north northeast and the west northwest direction were predominant, in the southwest, the northeast and the northwest direction were predominant. The included angle was about 60 to 80 degrees in the northeastern area and about 90 degrees in the southwestern area, and the dip angle was 60 to 80 degrees in both areas. The differences in the predominant direction in the northeastern part and the southwest part may proved by surveys which focusing on the presence or absence of minute displacement of individual joints, more extensive survey.