53 28 3 1 REPORT OF HYDROGRAPHIC AND OCEANOGRAPHIC RESEARCHES No.53 March, 2016 D Dbathymetric image of Nansei-Shoto Trench and its vicinity Noriaki IZUMI,AzusaNISHIZAWA,DaishiHORIUCHI,Yukari KIDO, Hideaki GOTO and Takashi NAKATA Abstract We interpreted seafloor topography using anaglyph images based on mdem processed from multi beam bathymetric data collected by Japan Coast Guard and JAMSTEC in the area around Nansei Shoto Trench, and made more precise submarine active faults map than that mapped by previous workers. In the southern part of the trench, trench parallel northwest dipping thrusts form extensive fault scarps on the lower part of landward trench, indicating that repeated large earthquakes and tsunamis have been generated along the trench. Some of the scarps extend over several hundred km and the longest one is about km. They are candidates for gigantic earthquake and tsunami generators. In the northern part, such scarps were scarcely recognized close to the trench axis due to collision of several bathymetric highs, while active reverse faults form distinctive fault scarps on the upper slope of the landward trench. They locate close to the island shelf, and are probably responsible to the uplift of islands forming Pleistocene and Holocene coastal terraces. JAM- STEC Received September, ; Accepted November, Hydrographic and Oceanographic Department, th R.C.G.Hqs. Ocean Research Laboratory,Technology Planning and International Affairs Division Continental Shelf Surveys Office, Hydrographic Surveys Division Japan Agency for Marine-Earth Science and Technology Hiroshima University Professor Emeritus of Hiroshima University 133
Noriaki IZUMI, Azusa NISHIZAWA, Daishi HORIUCHI, Yukari KIDO, Hideaki GOTO, and Takashi NAKATA AUV AUV http : //www.kaiho. mlit.go.jp/info/kouhou/h /k /k -.pdf http : // www.kaiho. mlit. go. jp / KIKAKU/press/ /H _kume.pdf Fig Fig Table JAMSTEC http : //www.godac.jamstec.go.jp/dataportal/viewer.htm JAMSTEC DARWIN : http : //www.godac.jamstec.go.jp /darwin/j Table Number of JAMSTEC research cruises that cover the area of Nansei-Shoto region. JAMSTEC JAMSTEC km Fig Track chart of JAMSTEC vessels around Nansei-Shoto Trench region. Ship s track lines of five research vessels are distinguished by different colors. JAMSTEC 134
3D bathymetric image of Nansei-Shoto Trench and its vicinity JAMSTEC mdem m DEM m ETOPO JAMSTEC m DEM m DEM NOAA ETOPO DEM SRTM MacOS DEM Simple DEM Viewer DEM https: //unit. aist.go.jp/igg/mgl-rg/ja/project/proj_offshore. html#okinawa Lallemand et al. D D m DEM Windows DEM Global Mapper D Fig Appendix Fig Fig m 135
Noriaki IZUMI, Azusa NISHIZAWA, Daishi HORIUCHI, Yukari KIDO, Hideaki GOTO, and Takashi NAKATA Fig Anaglyph image of the Nansei-Shoto Trench and its surrounding area. Black frame shows location of Figs.. Fig Fig 136
3D bathymetric image of Nansei-Shoto Trench and its vicinity Fig Bathymetry of the Nansei-Shoto Trench and its surrounding area. Contour interval is m. m. Fig m m m 137
Noriaki IZUMI, Azusa NISHIZAWA, Daishi HORIUCHI, Yukari KIDO, Hideaki GOTO, and Takashi NAKATA NNE SSW m m Nishizawa et al., Fig km Fig Anaglyph image and the map showing active faults thick red line: active fault, thick black line: presumed active fault, thin green line: active fault in young accretional prism, landslide dashed brown line and mud volcano back circle superimposed on bathymetry contours in m in the vicinity of Tanega-shima Island. m 138
3D bathymetric image of Nansei-Shoto Trench and its vicinity m braided pattern km m km km m Fig m m m m m m DEM Fig Anaglyph image and the map showing active faults thick red line: active fault, thick black line: presumed active fault, thin black line: normal fault on outer rise and landslide dashed brown line superimposed on bathymetry contours in m in the vicinity of Kikai-jima Island. m 139
Noriaki IZUMI, Azusa NISHIZAWA, Daishi HORIUCHI, Yukari KIDO, Hideaki GOTO, and Takashi NAKATA Fig Anaglyph image and the map showing active faults thick red line: active fault, red arrow: warping, thick black line: presumed active fault, thin red line: active fault in Okinawa Trough and submarine volcano red circle superimposed on bathymetry contours in m in the vicinity of Okinawa Island. m Fig m m m m 140
3D bathymetric image of Nansei-Shoto Trench and its vicinity m m Lallemand et al. Nakata and Kawana Fig Anaglyph image and the map showing active faults thick red line: active fault, thick black line: presumed active fault, thin red line: active fault in Okinawa Trough, thin blue line: presumed strike-slip fault, landslide dashed brown line and submarine volcano red circle superimposed on bathymetry contours in m in the vicinity of Sakishima Islands. m 141
Noriaki IZUMI, Azusa NISHIZAWA, Daishi HORIUCHI, Yukari KIDO, Hideaki GOTO, and Takashi NAKATA m m Fig Anaglyph image of old submarine volcanoes in the vicinity of Oki-Daito-jima Island. 142
3D bathymetric image of Nansei-Shoto Trench and its vicinity Fig A C A km m m B km m km C Ishizuka et al. B Ma Fig km km km m N E m N E Fig Anaglyph image and the map showing active faults red line: active fault, superimposed on bathymetry contours in m of northwest area of Okinawa Island. m 143
Noriaki IZUMI, Azusa NISHIZAWA, Daishi HORIUCHI, Yukari KIDO, Hideaki GOTO, and Takashi NAKATA Fig Fig Map showing active faults, volcanoes, landslides along Nansei-Shoto Trench thick red line: active fault, red arrow: warping, thick black line : presumed active fault, thin blue line: presumed strike-slip fault, thin green line: active fault in young accretion prism, thin red line: active fault in Okinawa Trough, thin blue line: presumed strike-slip fault, thin black line: normal fault on outer rise, landslide dashed brown line superimposed on bathymetry contours in m. m 144
3D bathymetric image of Nansei-Shoto Trench and its vicinity m DEM m m km km km km Lallemand et al. Lallemand et al., DEM m m 145
Noriaki IZUMI, Azusa NISHIZAWA, Daishi HORIUCHI, Yukari KIDO, Hideaki GOTO, and Takashi NAKATA km km M GPS M km M JAMSTEC no http: / / www.kaiho. mlit. go. jp / GIJUT- SUKOKUSAI / KENKYU / happyo /2011/h23p 07.pdf. 146
3D bathymetric image of Nansei-Shoto Trench and its vicinity Ishizuka, O., R. N. Taylor, Y. Ohara, andm. Yuasa Upwelling, rifting, and age-progressive magmatism from the Oki-Daito mantle plume, Geology,,. DEM D mdem D m DEM D DEM D m DEM D http : //jishin.go.jp/main/chousa/ feb_hyuganada/index.html. http : //www.jishin.go.jp/resource/column/ _ _ /. p. p. japan m. grd Lallemand, S., C. Liu, S. Dominguez, P. Schurle, J. Malavielle, and ACT Scientific Crew Trench-parallel stretching and folding of forearc basins and lateral migration of the accretionary wedge in the southern Ryukyus : A case of strain partition caused by oblique convergence, Tectonics,,. GPS 147
Noriaki IZUMI, Azusa NISHIZAWA, Daishi HORIUCHI, Yukari KIDO, Hideaki GOTO, and Takashi NAKATA JAMSTEC Nakata, T. and T. Kawana Historical and prehistorical large tsunamis in the southwestern Ryukyus, Japan, Tsuchiya, Y. and N. Shuto eds. Tsumani : Progress in prediction, Disaster Prevention and Warning, Kluwer Academic Press,. Nishizawa A, K. Kaneda, and M. Oikawa Seismic structure of the northern end of the Ryukyu Trench subduction zone, southeast of Kyushu, Japan, Earth Planets Space,, e e. JAMSTEC DEM DEM 148
Appendix Anaglyph image along Nansei-Shoto Trench.