| 講演要旨(和文) | | 地震防災の観点から，活断層の詳細な構造および活動履歴を把握することは重要とされる．過去の研究より，北上低地西縁断層帯の断層の長さおよび断層面の幅はそれぞれ62km，20-30kmとされ，活動時の地震の規模はマグニチュード7.8（MJ）程度と推定されている（地震調査研究推進本部, 2001および2009）．筆者等は，北上低地西縁断層帯のうち南側域（天狗森−出店断層群）の深部構造を詳細に把握することを目的とし，中型振源「EnviroVibe」を用いた反射法地震探査を実施した．調査の結果，深度2km程度までの詳細な地盤構造を把握することができ，地震防災対策を検討する上で有用な情報を得ることができた．本稿では，調査結果の速報を紹介するとともに，物理探査技術が地震防災対策上果たす役割について示す． |
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| | 講演要旨(英文) | | It is important to detect and delineate active fault structures in detail for the purpose of earthquake disaster countermeasures. In previous research, the Kitakami lowland west fault zone is known as an active thrust zone whose length and width are estimated at 62km and 20-30km respectively. The numerical research shows that the magnitude of an earthquake caused by this fault zone will be 7.8 (MJ). We implemented a seismic reflection survey at the southern part (the Tengumori-Dedana fault group) of this fault zone by using an EnviroVibe seismic source to delineate deep underground structures in detail. In this survey, we succeeded in delineating fault structures and evaluating the fault zone. In this paper, we will not only introduce our results, but also show the role of the geophysical technique in earthquake disaster countermeasures. |
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