Japan Geoscience Union Meeting 2016

Presentation information


Symbol S (Solid Earth Sciences) » S-SS Seismology

[S-SS24] Earthquake prediction and forecast

Thu. May 26, 2016 3:30 PM - 4:45 PM Poster Hall (International Exhibition Hall HALL6)

Convener:*Junichi Nakajima(Department of Earth and Planetary Sciences, Tokyo Institute of Technology)

3:30 PM - 4:45 PM

[SSS24-P05] The To-Nankai E.q. is previous and the Nankai E.q. occurs after it or with it, Elucidation of that mechanism

*Hirofumi Mase1 (1.none)

I explained that the right-turn of slab under Kii Peninsula is the To-Nankai Earthquake, and that the big earthquake which neighbors on it isn't also a simple plate boundary earthquake(1)(2)(3). I studied details around the turn-center this time. That was the drive part of the first half of the Nankai Earthquake, and of the mechanism that that can't explode first than the To-Nankai. (Please refer to the Fig.)(I call the subducting plate or slave the Lower, and call the part upper than it the Upper.)
The power that the mantle which flows to the east relatively pushes the edge of the Lower directly and makes the Lower turn to the right is the turn-drive-force(1). The reactions of it occur widely, but symbolic 6 are representation of all(Fig.1). The west(Area A) from the turn axis(fulcrum) is east-west extension area certainly by the reaction. At the east(Area B) from the fulcrum, doing a nose-dive from the shallow place and after forming the almost horizontal part, shocks will approach the Lower and be the part of make-landing(Sec.y5-Sec.y8). The Lower crawling up with turning rubbs, involves and assimilates the Upper that is rotated in advance. The horizontal part of preparations (turning face) will be formed so. I indicated the turning face at yellow coloring territory and indicated the part of make-landing at gray coloring territory (an orange broken line, centerline) (Fig.2). At the more east(Area C) I can't check the part of make-landing(Sec.y9-Sec.y10). Because the turn in the Lower is moderate (radius large) here, I think the Upper isn't captured.
High-density "High-speed body" touches the peninsula and goes through the Upper and Lower(each Fig. referring)(5). That's a man-shaped who consists of head and body, and depth 40km is neck. There will be time when movement and pressure in Area B shaves or improve, conversely, the "High-speed body" in existence. I regard the neck(Fig.1,depth 40km blue coloring) as the core which stays while thinning. Because the Lower is divided into a inside turn(Area B) and a outside turn(Area C) by collision with the core, and the outside turn is making a wide turn(Fig.1, black broken line arrow), the Lower separate inevitably in east and west at the south from the core. I think the rub of two boards causes pressure and increases density like an rubbing face of a stone-hand-mill and I think the discoid head is formed by it. But the head isn't plane symmetry in depth 25km(Fig.1,2,loop contour). Material partiality to the south and west is seen more in the upper part of the head.
Red arrows of Fig.2 are the observational data(7) by which the inside turn and the outside turn are surely indicated. The To-Nankai Earthquake was a right turn in the large-scale area which has started in the red asterisk from crushing in the Lower(1)(Fig.1). This is the outside turn. The real inside turn that mostly depends on interference of the rubbing face of the stone-hand-mill requires facts that the Lower can turn and advance to a shallow part. In other words, pressing-force-reduction from the outside-turn-part and preceding-destruction in the shallow part are wished for. Is there something equivalent to this inside turn besides The Nankai Earthquake which has started from the blue asterisk 2 years later of the To-Nankai(8)(9)?
(1)MASE/JpGU2014/SSS29-P10(2)MASE/SSJ2014FALL/S08-P11(3)MASE/JpGU2015/SSS31-P15(4)AIST/Visualization system for subsurface structures/all-Japan hypocenter catalog by the JMA/1995-2015/above M1(5)AIST/same to(4)/tomography data by Abdelwahed and Zhao (2007)dVp (6)JHOD,JCG/Seafloor Topography of the Plate Boundaries (7)GSI Home Page/ GEODETIC SURVEY/Crustal Movement in Japan/Long-term Information/Horizontal2005/10-2015/10fixed stn.NAKAMURA (8)(9)indicated on the drawing