Identification of active fault location using real-time ground measurements of atmospheric methane concentration by portable Cavity Ring-Down Spectroscopy system; Case study at the Atera fault

Shimo, Michito*; Niwa, Masakazu   ; Amano, Kenji  ; Tokunaga, Tomochika*; Tonokura, Kenichi*; Matsuoka, Toshifumi*; Biraud, S.*

Faults and associated fracture zones often provide the paths for migration of the gas, such as methane, hydrogen and helium, formed in the deep subsurface formations. In this study, we conducted the field measurement of methane gas concentration using a back-pack type portable Cavity Ring-Down Spectroscopy (CRDS) gas analyzer at the Atera fault area in Gifu prefecture. The measurement result suggests that the trace gas measurement using a CRDS technology can be one of the promising approaches to delineate the locations of the active faults creating migration paths of the deep-seated fluids.