9:15 AM - 9:30 AM
[SCG56-02] Seismicity, volcanism and active tectonics in central Japan
Keywords:Philippine Sea slab, Pacific slab, slab window
The geometry of the Philippine Sea slab subducting beneath the Japanese Islands has been imaged to 400 km depth beneath the Kyushu and Chugoku regions, whereas the Philippine Sea slab geometry beneath the Hokuriku region has only been determined to 140 km depth, thereby indicating a large east–west asymmetry in the subduction of the slab. However, geologic evidence suggests that there was symmetrical east–west seafloor spreading along the axis of the Kinan seamount chain when the Shikoku basin was an active spreading center in the Philippine Sea plate. This inconsistency suggests that the Philippine Sea slab should be present beneath the Hokuriku region.
The tomography results reveal a high-velocity anomaly at ~150–250 km depth that extends from Wakasa bay to Noto peninsula, and a slab window beneath the Hokuriku region. The numerical simulation results indicate that the Philippine Sea slab may have torn at 3-2 Ma.
The Philippine Sea slab and the Pacific slab are overlappingly subducted beneath central Japan and seismology and volcanism are affected by both slabs. We discuss tectonics in central Japan by comparing the geometry of the Philippine Sea slab with seismicity and volcanism.
The tomography results reveal a high-velocity anomaly at ~150–250 km depth that extends from Wakasa bay to Noto peninsula, and a slab window beneath the Hokuriku region. The numerical simulation results indicate that the Philippine Sea slab may have torn at 3-2 Ma.
The Philippine Sea slab and the Pacific slab are overlappingly subducted beneath central Japan and seismology and volcanism are affected by both slabs. We discuss tectonics in central Japan by comparing the geometry of the Philippine Sea slab with seismicity and volcanism.