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| | Abstract | | In order to develop the technique of site selection and environmental risk assessment in CO2 geological storage, we conducted electrical surveys in the Matsushiro area, Nagano, where a lot of spring water accompanied by CO2 gas was discharged along the crack and landslide caused by the Matsushiro earthquake swarm that mainly occurred from 1965 to 1970. The electrical data were collected and resistivity sections at depths of up to 60 m were obtained along five survey lines. Although the analyzed sections mainly correspond to the thick Quaternary sediments, many conductive zones appeared in high resistivity medium. We compared the sections with the result of electrical surveys which were conducted in 1967 in order to detect the change of hydrogeological structure in this area. The change is small for these forty years. It seems that there are many fractures which formed paths and reservoirs of ground water containing CO2 gas still now. |
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