Influence on groundwater flow conditions by groundwater pressure change induced by earthquakes; Case study of Tono Area

Takeuchi, Ryuji  ; Tsuyuguchi, Koji*; Onoe, Hironori ; Saegusa, Hiromitsu*; Beppu, Shinji

Assessment of the geological environment for the long term safety of geological disposal systems for high-level radioactive waste requires consideration for any phenomenon resulting in cumulative change to the geological environment at the regional scale. Groundwater pressure changes induced by earthquakes, for example, are one of the phenomena to be considered. Groundwater pressure changes induced by earthquakes have been observed during long-term monitoring carried out by Japan Atomic Energy Agency in the Tono Area, Gifu. In this paper, the observations of groundwater pressure change induced by earthquakes are summarized. In addition, an impact on groundwater flow conditions induced by earthquakes is discussed. In order to evaluate the long-term stability of groundwater flow condition, it is important to focus not only the change of groundwater pressure by earthquakes but also the change of the hydraulic gradient and hydraulic permeability.