日本地球惑星科学連合2018年大会

講演情報

[EJ] Eveningポスター発表

セッション記号 S (固体地球科学) » S-SS 地震学

[S-SS08] 活断層と古地震

2018年5月22日(火) 17:15 〜 18:30 ポスター会場 (幕張メッセ国際展示場 7ホール)

コンビーナ:小荒井 衛(茨城大学理学部理学科地球環境科学コース)、近藤 久雄(産業技術総合研究所 活断層・火山研究部門)、道家 涼介(神奈川県温泉地学研究所、共同)、松多 信尚(岡山大学大学院教育学研究科)

[SSS08-P01] 液状化から考える1586年天正地震の震源断層推定

*山村 紀香1加納 靖之2 (1.京都大学大学院理学研究科地球惑星科学専攻、2.京都大学防災研究所附属地震予知研究センター)

キーワード:1586年天正地震、液状化、N値、土質データ、PL値、震源断層

The Chubu region and the Kinki region in central Japan were widely and seriously damaged by the 1586 Tensho earthquake. The detail of this event is not well understood because highly trusted descriptions in historical documents for Tensho era are few. Previous researches have provided wide variety of arguments about location of source fault and magnitude of this event, which yield several differing interpretations. In this study, we focus on liquefaction of ground which has been not intensively investigated ever. The 6 areas under consideration involve some sites of liquefaction observed at ruins or recorded in highly trusted historical documents. We estimate source fault of this event by calculating possibility of liquefaction to seismic motion in case of occurrence with assumption of source faults. Assumption of source faults are Yoro-Kuwana-Yokkaichi faults (Mj8.0), southern part of Atera fault group (Mj7.8) and Shokawa fault group (Mj7.9). Predicted seismic intensity is calculated using Estimation Tools for Earthquake Ground Motion by attenuation curve of J-SHIS. The possibility of liquefaction is evaluated by PL-value which is calculated using predicted seismic intensity and borehole data (including N-value and soil data). Borehole data from 352 boring sites in Geo-Station of NIED, PWRI and Shiga Prefecture are used. As a result, PL-value is large in all these areas in case of occurrence a single earthquake of Mj7.9 in the Shokawa fault group. It means that the event likely cause liquefaction and can explain liquefaction in all these areas. We suggest that most possible source fault of the Tensho earthquake is the Shokawa fault group.