地震 第2輯
Online ISSN : 1883-9029
Print ISSN : 0037-1114
ISSN-L : 0037-1114
論説
反射法解析および波線追跡による走時解析を用いた北美濃地域の地下構造の推定
江元 智子津村 紀子古屋 裕濃尾地震断層域合同地震観測グループ
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ジャーナル フリー

2015 年 68 巻 2 号 p. 17-29

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To determine crustal structure of the Neodani Fault zone, where the largest inland Nobi earthquake occurred in 1891, an active-source seismic experiment was carried out in the northern Mino region, central Japan. The shots were recorded by seismic array stations settled across the Neodani Fault Zone and we applied seismic reflection analysis to the data and obtained reflection profiles of the crust. Then we estimated crustal velocity by forward modeling using travel times of first break and reflected waves. We found significant reflections with duration of 2 s around 10 s two way travel time. Based on comparisons with other reflection profiles, we interpreted the events to come from the laminated lower crust within the overriding plate. The depth of the laminated crust varies across the Neodani Fault Zone, which is shallower in the southwest than in the northeast, implying that displacement along the Neodani faults extends to the deep crust. In the southwestern part of study area, the top of the Philippine Sea plate (PSP) estimated from travel time tomography is shallower than the lower limit of the laminated lower crust. We thus suggest that the subducting PSP may contact with the bottom of the overriding crust beneath the northern Mino district.

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© 2015 公益社団法人 日本地震学会
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