Displacement Above the Hypocenter of the 2011 Tohoku-Oki Earthquake

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Science  19 May 2011:
DOI: 10.1126/science.1207401


The moment magnitude (Mw) = 9.0 2011 Tohoku-Oki megathrust earthquake occurred off the coast of northeastern Japan. Combining Global Positioning System (GPS) and acoustic data, we detected very large seafloor movements associated with this event directly above the focal region. An area with more than 20 meters of horizontal displacement—that is, four times larger than those detected on land—stretches several tens of kilometers long along the trench; the largest amount reaches about 24 meters toward east-southeast just above the hypocenter. Furthermore, nearly 3 meters of vertical uplift occurred, contrary to observed terrestrial subsidence.