Extensive fault rupture reached Japan trench is landslide

Takashi NAKATA; Hideaki GOTO; Hidekazu TOKUYAMA

Presentation information

Oral

Symbol M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS33] Progress in marine geoscience off Pacific coast of Tohoku after the 2011 earthquake and tsunami

Tue. May 26, 2015 11:00 AM - 12:45 PM 102B (1F)

Convener:*Kazuko Usami(Institute of Geology and Geoinformation, National Institute of Advanced Industrial Science and Technology), Ken Ikehara(Institute of Geology and Geoinformation, National Institute of Advanced Industrial Science and Technology), Yoshihiro Ito(Disaster Prevention Research Institute, Kyoto University), Takashi Toyofuku(Japan Agency for Marine-Earth Science and Technology (JAMSTEC)), Chair:Ken Ikehara(Institute of Geology and Geoinformation, National Institute of Advanced Industrial Science and Technology)

12:30 PM - 12:33 PM

[MIS33-P01] Extensive fault rupture reached Japan trench is landslide

3-min talk in an oral session

*Takashi NAKATA¹, Hideaki GOTO², Hidekazu TOKUYAMA³ (1.Professor Emeritus, Hiroshima University, 2.Hiroshima University, 3.Kochi University)

Keywords:Japan trench, submarine landslide, submarine active fault, 2011 Earthquake

Analysis on topographical change caused by the 2011 off the. Pacific coast of Tohoku Earthquake was carried out by using anaglyph images based on multi-narrow beam data collected by JAMSTEC and Japan Coast Guard. Apparent and distinctive change is not widely observed in spite of the large earthquake mainly because of rather coarse DEM grid (150 m ), except along the seafloor of Japan trench between N 38.0 and N 38.2 where JAMSTEC claims based on topographical and structural changes after the earthquake that displacement over 50 m of the earthquake source fault reached the trench axis. However, detailed observation on anaglyph images reveals that such changes were caused by re-activation of pre-existing landslides located along the toe of a gigantic slope failure located near the epicenter. Mounds appeared along the trench axis probably rotating mass of landslide.