| 講演要旨(和文) | | 広範囲かつ深部までの活断層の地下構造の把握を目的として，反射法地震探査を始め，物理探査が広く用いられている．本研究では，多点同時測定が可能な電磁探査装置Geode EM3Dによる高密度CSAMT探査を青森湾西断層および千屋断層に適用した．青森湾西断層では反射法地震探査（楮原ほか，2017）および重力探査（岡田ほか，2018）と一部重なる全長6.1kmの測線で高密度アレイ式CSAMT探査を実施し，逆断層の変位に伴う比抵抗構造のギャップに加え，断層近傍の破砕領域を示唆する低比抵抗領域が認められた．千屋断層では反射法地震探査（佐藤・平田，1998）の測線とほぼ同一な全長5.7kmの測線上で高密度CSAMT探査を実施し，断層と貫入岩の影響で泥岩層が複雑な変形をしたことを示唆する比抵抗構造を得た．ともに他の手法では認められなかった特徴的な構造が新しく得られ，高密度CSAMT探査の有効性が示された． |
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| | 講演要旨(英文) | | The utilization of geophysical investigation in active fault survey is effective in clarifying subsurface fault structure in spatial manner. We conducted a high density CSAMT survey across the two active faults that had been conducted geophysical surveys such as reflection and gravity. The result of the investigation at the Aomori-wan west fault (AWF) shows the sharp low resistivity zone and displacement of low resistivity zone that were interpreted fault zone conductor (FZC) of AWF and displaced mud rock. The result of the investigation at the Senya fault shows the complex low resistivity structure that was interpreted displacement of mud rock caused by thrust-front migration. Thus the result which derived from CSAMT survey contributed to interpret fault structure in detail, we concluded that applying high density CSAMT survey combining with other geophysical survey to active fault is more effective. |
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