The submarine fault scarp of the 2011 Tohoku-oki Earthquake in the Japan Trench

Rupture of the plate boundary fault during the 2011 Tohoku-oki earthquake with moment magnitude 9.0 is thought to have propagated to the trench. Surface exposure of the fault has not yet been confirmed because of great depths that are challenging to access and study. Using a manned submersible in th...

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Bibliographic Details
Published in:	Communications earth & environment Vol. 4; no. 1; pp. 476 - 10
Main Authors:	Ueda, Hayato, Kitazato, Hiroshi, Jamieson, Alan, Bond, Todd, Cardigos, Sara, Funaki, Masayoshi, Maroni, Paige J., Nanbu, Hiroyasu, O’Callaghan, Joanne M., Onishi, Takuma, Pedersen, Silje W., Roperez, Jaya, Tsuruzono, Hiroumi, Watanabe, Hiromi K., Yasuda, Tetsuro
Format:	Journal Article
Language:	English
Published:	London Nature Publishing Group 01-12-2023 Springer Nature Nature Portfolio
Subjects:	Cliffs Dipping Earthquakes Escarpments Geological faults Ocean floor Plates (tectonics) Seismic activity Slip Subduction (geology) Water depth Japan
Online Access:	Get full text
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Summary:	Rupture of the plate boundary fault during the 2011 Tohoku-oki earthquake with moment magnitude 9.0 is thought to have propagated to the trench. Surface exposure of the fault has not yet been confirmed because of great depths that are challenging to access and study. Using a manned submersible in the Japan Trench, we explored and visually assessed the seafloor near the epicenter. On the eastern slope of a thrust ridge 59 m high, which appeared after the earthquake, we found a 26 m high subvertical cliff regarded as the fault scarp. Cross-section analysis suggests an 80–120 m slip on the fault when assumed to dip at 45–30°, to build up the observed relief. The estimated larger displacement in the trench than in more proximal parts can be attributed to local enhancement of the slip by extension of the wedge above a subducting graben on the Pacific plate.
Bibliography:	Communications Earth & Environment
ISSN:	2662-4435 2662-4435
DOI:	10.1038/s43247-023-01118-4