Near-trench slip potential of megaquakes evaluated from fault properties and conditions.
Near-trench slip during large megathrust earthquakes (megaquakes) is an important factor in the generation of destructive tsunamis. We proposed a new approach to assessing the near-trench slip potential quantitatively by integrating laboratory-derived properties of fault materials and simulations of fault weakening and rupture propagation. Although the permeability of the sandy Nankai Trough materials are higher than that of the clayey materials from the Japan Trench, dynamic weakening by thermally pressurized fluid is greater at the Nankai Trough owing to higher friction, although initially overpressured fluid at the Nankai Trough restrains the fault weakening. Dynamic rupture simulations reproduced the large slip near the trench observed in the 2011 Tohoku-oki earthquake and predicted the possibility of a large slip of over 30 m for the impending megaquake at the Nankai Trough. Our integrative approach is applicable globally to subduction zones as a novel tool for the prediction of extreme tsunami-producing near-trench slip.
Department of Earth and Space Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
Tetsuro
T
Hirono
Center for Safety and Reliability Engineering, Institute of Technology Shimizu Corporation, Koto, Tokyo 135-8530, Japan.
Kenichi
K
Tsuda
Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, Nankoku, Kochi 783-8502, Japan.
Wataru
W
Tanikawa
Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA.
Jean-Paul
JP
Ampuero
International Institute of Seismology and Earthquake Engineering, Building Research Institute, Tsukuba, Ibaraki 305-0802, Japan.
Bunichiro
B
Shibazaki
Earthquake Research Institute, University of Tokyo, Bunkyo, Tokyo 113-0032, Japan.
Masataka
M
Kinoshita
Earthquake Hazards Division, Disaster Prevention Research Institute, Kyoto University, Uji, Kyoto 611-0011, Japan.
James J
JJ
Mori