社団法人　物理探査学会
第143回(2020年度秋季)学術講演会

超臨界地熱へむけての地震波モニタリング：九州メディポリス地熱フィールドにおける第二回評価試験

講演要旨(和文) 講演要旨(英文) We conducted a second DAS seismic study in 2019. We deployed the optical-fiber system at a 1,545-m depth in a borehole. We conducted DAS-offset VSP at five locations and performed a frequency sweep of 10-75 Hz. To enhance the S/N we operated MiniVib 8 hours each day for five days. Stacking for 480 or 960 times considerably improved the arrival waveforms. Based on an analysis of DAS data, we constructed the 2D seismic profile. We estimated three major hydrothermal layers, at depths of 800-1,000 m, 1,300-1,600 m, and 3,600 m. The zone around 3,600 m suggests a high Vp/Vs value and the possible presence of a fluid layer.