9:45 AM - 10:00 AM
[SCG52-04] Forearc segmentation: an example of the Tonankai-Tokai regions in the Nankai Trough from new seismic reflection data set
★Invited Papers
Keywords:Nankai Trough, forearc segmentation, accretionary complex, large earthquake, subduction zone, Philippine Sea Plate
Large earthquakes and tsunamis are the most serious hazardous phenomena for the societies facing to the subduction zone, that is generally segmented into several regions. The Nankai Trough in Japan is a trench where the large earthquakes and tsunamis repeatedly occurred and the next disaster within a few decades is anticipated (The headquarters of Earthquake Research Promotion, Japan, 2025).
The Philippine Sea Plate converges with the Honshu mainland of the hanging-wall Amurian plate (a part of Eurasian Plate; Argus et al., 2011) and underthrusts along the Nankai Trough. Easternmost part of the Philippine Sea plate, the Izu-Bonin Arc, is now colliding to the Honshu near the metropolitan Tokyo.
In the Nankai convergent zone, seabed topography, forearc geology, megathrust geometry, large earthquake rupture area, and slow-earthquake distribution are segmented into several regions, but their intimate relationships are ambiguous and the matter of concern.
One of the specific matters in this paper is the segmentation of the Tokai area off Enshu in central Japan and the Tonankai area off Kumano of the Kii Peninsula, southwest Japan. It is quite important to understand this segment boundary for the next Nankai earthquake rupture possibly beyond this segment boundary.
We analyzed the newly acquired 2D and 3D seismic reflection profiles covering the Tokai-Tonakai segments boundary area and revealed the structural relationship among the upper plate structures , and geometry of plate boundary decollement. A collision-like structure characterizes the segment boundary zone.
acknowledgment & references:
We are grateful to Ministry of Economy Trade and Industry for inspecting new data set.
Argus, D. F., Gordon, R. G., & DeMets, C. (2011). Geologically current motion of 56 plates relative to the no-net-rotation reference frame. Geochemistry, Geophysics, Geosystems, 12(11).
The headquarters of Earthquake Research Promotion, Japan, 2025: URL.https://www.jishin.go.jp/
The Philippine Sea Plate converges with the Honshu mainland of the hanging-wall Amurian plate (a part of Eurasian Plate; Argus et al., 2011) and underthrusts along the Nankai Trough. Easternmost part of the Philippine Sea plate, the Izu-Bonin Arc, is now colliding to the Honshu near the metropolitan Tokyo.
In the Nankai convergent zone, seabed topography, forearc geology, megathrust geometry, large earthquake rupture area, and slow-earthquake distribution are segmented into several regions, but their intimate relationships are ambiguous and the matter of concern.
One of the specific matters in this paper is the segmentation of the Tokai area off Enshu in central Japan and the Tonankai area off Kumano of the Kii Peninsula, southwest Japan. It is quite important to understand this segment boundary for the next Nankai earthquake rupture possibly beyond this segment boundary.
We analyzed the newly acquired 2D and 3D seismic reflection profiles covering the Tokai-Tonakai segments boundary area and revealed the structural relationship among the upper plate structures , and geometry of plate boundary decollement. A collision-like structure characterizes the segment boundary zone.
acknowledgment & references:
We are grateful to Ministry of Economy Trade and Industry for inspecting new data set.
Argus, D. F., Gordon, R. G., & DeMets, C. (2011). Geologically current motion of 56 plates relative to the no-net-rotation reference frame. Geochemistry, Geophysics, Geosystems, 12(11).
The headquarters of Earthquake Research Promotion, Japan, 2025: URL.https://www.jishin.go.jp/