Examination of evaluation method for fault activity based on an observation of fault zone; Selection of outcrops, in-situ experiments

Kametaka, Masao*; Okazaki, Kazuhiko*; Nakayama, Kazuhiko ; Seshimo, Kazuyoshi ; Aoki, Kazuhiro ; Tanaka, Yoshihiro; Shimada, Koji   ; Suzuki, Kazushige*; Shimogama, Kota*; Inada, Noriyuki*

The evaluation of an fault activity has been done by an observation of deformation of overlying strata of the fault. However, it is difficult to evaluate the activity where the fault zone appears only in a basement rock with no overlying strata. We have been carried out the observation of the fault zone to establish the method of evaluation of fault activity. We selected the outcrops through literature and surface geological survey. Examples of outcrops of active fault are outcrops of Gosukebashi Fault in the Rokko-Awaji Fault Zone and the Rokko Fault in the Arima-Takatsuki Tectonic Line, southern Hyogo Prefecture. An example of non-active fault is outcrop of the fault around the Rokko Horai-kyo in the northern Rokko Mountains. In this study, we focus on the easy evaluation method in the field, and described about suitability of observation of fault plane, in-situ experiments of hardness and color.