A three-dimensional seismic survey was carried out at the western Nankai trough accretionary wedge in 1999. This experiment was a Japan-U.S. collaborative investigation on seismogenic zones. The cruise imaged an 8 x 80 km area with 81, 80-km-long, high quality, seismic reflection lines, all of which have nearly continuous coverage. The main objective of our experiment was to image the plate boundary fault at which major earthquakes and tsunamis are generated. A preliminary interpretation was conducted based on a primary data processing and we proposed a well imaged structure of up-dip limit of seismogenic zone, where a décollement plane touches the oceanic plate (layer II) down in first. We identified that the boundary between the stable sliding zone (ocean-ward) and the unstable stick slip zone (landward) is located there.
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A perspective view of 3-D interpretation at the proposed inter-plate seismogenic zone (up-dip limit) in the Nankai subduction margin |
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| Relational Information |
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AIST Today Vol. 1, No. 5 (2001) 12
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No.2 2001
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