Geosphere stability project, 2; Development of geological-evolutionary model in the Horonobe area

Matsuoka, Toshiyuki; Komatsu, Tetsuya  ; Yasue, Kenichi; Onoe, Hironori ; Oyama, Takuya ; Iwatsuki, Teruki  ; Sasao, Eiji   ; Umeda, Koji

This paper summarized the current status of R&D activities with development of geological-evolutionary model in the Horonobe area, northern Hokkaido. This study has been carried out in the area of approx. 100 km 30 km. Two stages, approx. 1 Ma and 0.33 Ma were selected for paleo-geological modeling based on geological history of several millions of years in and around the study area. 3D steady-state groundwater flow simulations and sensitivity analysis using these models were carried out. Long-term evolution of groundwater flow conditions caused by long-term geological phenomena was assessed using statistical analysis. From the results, the spatial distribution of long-term stability of groundwater flow conditions were estimated and important factors for assessment of long-term evolution of groundwater flow conditions were extracted. In addition, the results of groundwater flow simulation were analyzed from the viewpoint of geochemical environment within the groundwater.