1:45 PM - 3:15 PM
[SCG62-P04] Image of Philippine Sea plate beneath the Izu collision zone
Keywords:Izu collision zone, Philippine Sea plate, oceanic crust, oceanic mantle
Map views clearly image the high-V Sambagawa belt and low-V Shimanto belt dipping to north. Low-V oceanic crust and high-V oceanic mantle of the PHS plate are also clearly imaged.
EW cross section clearly image the high-V oceanic mantle on the southern side of 35.7°N, however, subducting high-V zone is not clear on the northern sude of 35.8°N. NS cross section clearly image the subducting high-V PHS plate from south the Kanto region on the eastern side of 139.4°E, however, large low-V block exists at depths of 25-60 km from Izu peninsula to Izu collision zone on the western side of 139.5°E. High-V oceanic mantle of PHS plate at depths deeper than 40 km on the northern side of 35°N and western side of 138.2°E.
Comparison with the receiver function and reflection seismology found that the isovelocity line with 6.5 km/s of P-wave is consistent with the upper boundary of the PHS plate. This isovelocity line suddenly change at the Tanzawa Mountain range. This line lays at depths of 25 km on the eastern side, however, this line lays at depths of 15-20km on the western side and dipping to west.