Spatial and temporal evolution of the megasplay fault in the Nankai Trough

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doi: 10.1029/2010GC003335
Author(s): Kimura, Gaku; Moore, Gregory F.; Strasser, Michael; Screaton, Elizabeth J.; Curewitz, Daniel; Streiff, Carolyn; Tobin, Harold
Author Affiliation(s): Primary:
University of Tokyo, Department of Earth and Planetary Science, Tokyo, Japan
University of Hawaii at Manoa, United States
University of Bremen, Germany
University of Florida, United States
Syracuse University, United States
University of Wisconsin-Madison, United States
Volume Title: Geochemistry, Geophysics, Geosystems - G<sup>3</sup>
Source: Geochemistry, Geophysics, Geosystems - G>3`, Vol.12. Publisher: American Geophysical Union and The Geochemical Society, United States. ISSN: 1525-2027
Note: In English. 51 refs.; illus., incl. sketch map
Summary: The temporal and spatial evolution of a seismogenic megasplay fault in the Kumano area, Nankai Trough (southwest Japan), is revealed by detailed investigation of the three-dimensional structure of the shallow portions of the fault, combined with the results of drilling and dating of cores from Integrated Ocean Drilling Program (IODP) Expedition 316. The ENE striking eastern portion of the splay fault has remained active since the inception of faulting at ∼1.95 Ma. The recent shortening rate is ∼1 m/kyr, which represents ∼1.5%-2.5% of the total plate convergence rate of ∼40-65 m/kyr. The NE striking western portion of the splay fault exhibits a different mode of activity. Early stage activity (before 1.55 Ma) was similar to the eastern portion, but the fault was inactive between 1.55 and 1.24 Ma. The fault was reactivated for a short time at ∼1.24 Ma but again ceased activity after formation of the secondary branch and has been inactive since 1.24 Ma. Cessation of splay fault activity in the western domain after 1.55 Ma may be due to collision with a seamount and resulting bending of the accretionary prism in the splay fault footwall. Continuous activity of the eastern domain of the splay fault after 1.24 Ma may be related to geometrical favorability due to reorientation of the fault after the seamount passed beneath the imbricate thrust zone, leading to initiation of slightly oblique subduction.
Year of Publication: 2011
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 16 Structural Geology; Accretionary wedges; Earthquakes; Expedition 316; Faults; Fractures; Integrated Ocean Drilling Program; NanTroSEIZE; Nankai Trough; North Pacific; Northwest Pacific; Oblique orientation; Pacific Ocean; Plate tectonics; Seismicity; Subduction; Subduction zones; Three-dimensional models; Tsunamis; West Pacific
Coordinates: N310000 N350000 E1390000 E1330000
Record ID: 2013046489
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