著者

徳山 英一 本座 栄一 木村 政昭 倉本 真一 芦 寿一郎 岡村 行信 荒戸 裕之 伊藤 康人 除 垣 日野 亮太 野原 壮 阿部 寛信 坂井 眞一 向山 建二郎

出版者

海洋調査技術学会

雑誌

海洋調査技術 (ISSN:09152997)

巻号頁・発行日

vol.13, no.1, pp.27-53, 2001-03-31

参考文献数

56

被引用文献数

6

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We propose the guideline to identify fault in offshore region mainly based on MCS profiles, combining high resolution bathymetric maps and geological data such as bore hole results. Based on the guideline we distinguished total 776 faults developing around Japan since the latest Miocene and 753 faults out of total numbers of faults are interpreted to have been active by Quaternary. Together with distinguishment of fault we examined the attributes of each faults such as surface and vertical distribution, criteria of offset, age of movement, certainty of a fault and so on. <br>The results of the distinguishment and examination of the fault leads to the conclusion that the ongoing tectonic framework around Japan characterized by 1) oblique Subduction along the Nankai Trough, 2) rifting at the Okinawa Trough, 3) E-W compressionl regeme along the Japan Sea margin, 4) E-W compressionl regeme along southwestern margin of the Okhotsk Sea and off southern Hokkaido, 5) E-W compressionl regeme along the Japan Trench, 6) rifting in the central arc of the Izu-Ogasawara Arc has been established since 3 Ma, at the earliest 6 Ma. <br>We utilized high resolution data set which we enable to access. Tow big problems, however, still remain in terms of reliability of fault recognition. Those are 1) age of fault movement and 2) spatial distribution of fault. To solve the first one, new technique is required in order to obtain core samples which provide critical evidence to determine age of fault movement. As is second problem concerned, new intensive seismic survey is indispensable to make a precise fault distribution map, especially in the boundary area between land and sea.

著者

岩淵 洋 向山 建二郎

出版者

一般社団法人 日本地質学会

雑誌

地質学雑誌 (ISSN:00167630)

巻号頁・発行日

vol.112, no.8, pp.531-534, 2006 (Released:2006-12-02)

参考文献数

15

被引用文献数

2 1

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Elongated trough-like depressions were discovered on the shelf break, southwest off the Kyushu. Each depression is 200−250 meters in width, hundreds meters to 2 kilometers in length and 10−20 meters in relative depth. The depressions are discontinuously aligned for 18 kilometers parallel to the strike of the shelf slope. The shelf and upper shelf slope consist of a deposit of the Pleistocene Ito pyroclastic flow in origin. The distribution of the depressions and geological information indicate that the depressions are not any of erosional features by tidal currents or gravitational flows, but “crown crack”, which is a kind of tensional cracks on the top of a submarine slide body during the initial stage of sliding.