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Structure and Composition of the Plate-Boundary Slip Zone for the 2011 Tohoku-Oki Earthquake

2013; American Association for the Advancement of Science; Volume: 342; Issue: 6163 Linguagem: Inglês

10.1126/science.1243719

1095-9203

F. M. Chester, C. D. Rowe, Kohtaro Ujiie, J. D. Kirkpatrick, Christine Regalla, Francesca Remitti, Jo Moore, Virginia Toy, Monica Wolfson‐Schwehr, Santanu Bose, J. Kameda, James Mori, E. E. Brodsky, Nobuhisa Eguchi, Sean Toczko, Expedition, The Expedition Scientists,

Seismic Waves and Analysis

The mechanics of great subduction earthquakes are influenced by the frictional properties, structure, and composition of the plate-boundary fault. We present observations of the structure and composition of the shallow source fault of the 2011 Tohoku-Oki earthquake and tsunami from boreholes drilled by the Integrated Ocean Drilling Program Expedition 343 and 343T. Logging-while-drilling and core-sample observations show a single major plate-boundary fault accommodated the large slip of the Tohoku-Oki earthquake rupture, as well as nearly all the cumulative interplate motion at the drill site. The localization of deformation onto a limited thickness (less than 5 meters) of pelagic clay is the defining characteristic of the shallow earthquake fault, suggesting that the pelagic clay may be a regionally important control on tsunamigenic earthquakes.