Geosphere stability project, 1; Development of geological-evolutionary model in the Tono area

Onoe, Hironori ; Komatsu, Tetsuya  ; Yasue, Kenichi; Iwatsuki, Teruki  ; Takeuchi, Ryuji  ; Kato, Tomoko ; Sasao, Eiji   ; Umeda, Koji

This paper summarized the current status of R&D activities with development of geological-evolutionary model in the Tono area, Central Hokkaido. This study has been carried out in the area of approx. 20 km square. Four stages, approx. 3Ma, 1Ma, 0.45Ma and 0.14Ma 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.