著者
倉本 真一
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.115, no.9, pp.483-487, 2009 (Released:2010-03-10)
参考文献数
12

This report introduces the scientific drilling project “NanTroSEIZE (Nankai Trough Seismogenic Zone Experiment)” proposed for the IODP (Integrated Ocean Drilling Program). NanTroSEIZE is a large, international, multidisciplinary scientific project that required long-term planning and implementation. The project involved almost two decades of planning and may continue for another decade while carrying out drilling, coring, and long-term borehole monitoring. This large scientific project has now officially started, and we expect that the resulting scientific findings will be of international significance.
著者
倉本 真一 平 朝彦 Bangs Nathan L. SHIPLEY Thomas H. MOORE Gregory F. EW99-07 08 航海乗船研究者
出版者
Tokyo Geographical Society
雑誌
地學雜誌 (ISSN:0022135X)
巻号頁・発行日
vol.109, no.4, pp.531-539, 2000-08-25
被引用文献数
10 15

A three-dimensional seismic survey was carried out at the western Nankai Trough accretionary wedge from June 18 to August 18, 1999. This experiment was Japan-U.S. collaborative investigation on seismogenic zones. The cruise imaged an 8 X 80 km area with 81, 80km-long, high quality, seismic reflection lines, all of which have nearly continuous coverage.<BR>The main objective of our experiment was to image the plate boundary fault at which major earthquakes and tsunamis are generated. Our primary goal is to image the thrust and identify the boundary between aseismic and seismic zones for a large inter-plate earthquake.<BR>On-board two-dimensional data processing has been carried out. This gives us a significantly clear image of the inner structure of the accretionary wedge at our survey area. One impressive image of the profile shows the large thrust slice zone that is classified by our interpretation. A number of out-of-sequence thrusts have developed and are concentrated in the area where the water depth is approximately 4, 000 to 3, 000m. A decollement plane touches the oceanic plate (layer II) down at there in first. We identified that the boundary between the stable sliding zone (ocean-ward) and the unstable stick slip zone (landward) is located there. We propose that the boundary is the up-dip limit of the seismogenic zone. Further data processing is ongoing. A true three-dimensional structure will reveal much more details and a clear image of seismogenic zone at the Nankai subduction margin.