期刊
JOURNAL OF ASIAN EARTH SCIENCES
卷 78, 期 -, 页码 277-290出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jseaes.2012.12.031
关键词
Subduction zone; Slab structure; Mantle upwelling flow; Arc magmatism; Earthquake generation; Japanese Islands
资金
- Global Education and Research Center for Earth and Planetary Dynamics Global COE Program at Tohoku University
- Geofluids: Nature and Dynamics of Fluids in Subduction Zones Scientific Research Program on Innovative Areas at Tokyo Institute of Technology
- Grants-in-Aid for Scientific Research [22340126, 21109002] Funding Source: KAKEN
A dense nationwide seismic network recently constructed in Japan has resulted in the production of a large amount of high-quality data that have enabled the high-resolution imaging of deep seismic structures in the Japanese subduction zone. Seismic tomography, precise locations of earthquakes, and focal mechanism research have allowed the identification of the complex structure of subducting slabs beneath Japan, revealing that the subducting Philippine Sea slab underneath southwestern Japan has an undulatory configuration down to a depth of 60-200 km, and is continuous from Kanto to Kyushu without disruption or splitting, even within areas north of the lzu Peninsula. Analysis of the geometry of the Pacific and Philippine Sea slabs identified a broad contact zone beneath the Kanto Plain that causes anomalously deep interplate and intraslab earthquake activity. Seismic tomographic inversions using both teleseismic and local events provide a clear image of the deep aseismic portion of the Philippine Sea slab beneath the Japan Sea north of Chugoku and Kyushu, and beneath the East China Sea west of Kyushu down to a depth of 450 km. Seismic tomography also allowed the identification of an inclined sheet-like seismic low-velocity zone in the mantle wedge beneath Tohoku. A recent seismic tomography work further revealed clear images of similar inclined low-velocity zones in the mantle wedge for almost all other areas of Japan. The presence of the inclined low-velocity zones in the mantle wedge across the entirety of Japan suggests that it is a common feature to all subduction zones. These low-velocity zones may correspond to the upwelling flow portion of subduction-induced convection systems. These upwelling flows reach the Moho directly beneath active volcanic areas, suggesting a link between volcanism and upwelling. (C) 2013 Elsevier Ltd. All rights reserved.
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