JpGU-AGU Joint Meeting 2020

Presentation information

[E] Poster

S (Solid Earth Sciences ) » S-CG Complex & General

[S-CG61] The Japan Trench: Learning from the 2011 M=9 Tohoku-Oki earthquake, a decade later

convener:Takeshi Iinuma(National Research and Development Agency Japan Agency for Marine-Earth Science and Technology), Asuka Yamaguchi(Atomosphere and Ocean Research Institute, The University of Tokyo), Aitaro Kato(Earthquake Research Institute, the University of Tokyo), Tianhaozhe Sun(Pacific Geoscience Centre, Geological Survey of Canada)

[SCG61-P05] Structural-morphological and sedimentary features of forearc slope off Miyagi, NE Japan: implications for development of forearc basins and plumbing systems

*Jih-Hsin Chang1, Jin-Oh Park2, Tzu-Ting Chen3, Asuka Yamaguchi2, Tetsuro Tsuru4, Yuji Sano2, Ho-Han Hsu3, Kotaro Shirai2, Takanori Kagoshima2, Kentaro Tanaka2, Chiori Tamura2 (1.Geological Survey of Japan, National Institute of Advanced Industrial and Science Technology., 2.Atmosphere and Ocean Research Institute, The University of Tokyo., 3.Institute of Oceanography, National Taiwan University., 4.Tokyo University of Marine Science and Technology.)

Keywords:forearc slope, isolated basin, forearc trough, liquefaction

Multibeam (MB) and subbottom profile (SBP) data along the forearc slope off Miyagi, Japan, are combined to investigate structural-morphological and sedimentary structures along the forearc slope of the Japan Trench subduction zone. In addition to dip-oriented slope gullies, the MB data image a nearly dip-perpendicular slope trough bounded by a fault scarp landward of the trench-slope break. Seaward of the trench-slope break, the subbottom mostly contains normal faults that dip in opposite direc- tions. The SBP data show not only unconformity and sliding surfaces, but also underfilled (forearc trough) and filled structures that may reflect the most recent forearc subsidence and basin filling. We propose these forearc trough and associated filling structures may indicate the earliest developments of modern isolated basins. Thus, a model of forearc basin development from slope gully to slope trough, isolated basins and forearc basin, transferred by active structures, could be proposed. Observed seafloor liquefaction in the SBP data may represent a near-surface seep structure of a plumbing system that enables hydrosphere- mantle fluid migration plausibly activated by earthquake cycles.