Was the 2011 Tohoku-Oki earthquake preceded by aseismic preslip? Examination of seafloor vertical deformation data near the epicenter

R. Hino, D. Inazu, Y. Ohta, Y. Ito, S. Suzuki, Takeshi Iinuma, Y. Osada, M. Kido, H. Fujimoto, Y. Kaneda

Research output: Contribution to journalArticlepeer-review

30 Citations (Scopus)

Abstract

Ocean-bottom pressure records obtained near the epicenter of the 2011 Tohoku-Oki earthquake were examined to test whether the earthquake was preceded by substantial precursory crustal deformation. The seafloor data enabled us to search for small-scale preslip near the epicenter that would be difficult to identify from terrestrial geodetic data. After treating the data to reduce nontectonic fluctuations, we obtained a time series of seafloor vertical deformation in the epicentral region with a noise level of 2–4 cm. No significant crustal deformation related to preslip was detected in the period of roughly a day before the mainshock, whereas postseismic deformation associated with the largest foreshock 2 days before the mainshock was apparent. From our quantitative estimate of the sensitivity of the seafloor network in detecting slip on the plate interface, we conclude that the Tohoku-Oki earthquake was not preceded by preslip with moment release greater than moment magnitude (Mw) 6.2 in the vicinity of the hypocenter or greater than Mw 6.0 along the subduction interface near the trench.

Original languageEnglish
Pages (from-to)181-190
Number of pages10
JournalMarine Geophysical Research
Volume35
Issue number3
DOIs
Publication statusPublished - 2014 Jan 1

Keywords

  • Interplate megathrust earthquake
  • Ocean-bottom pressure monitoring
  • Precursory slip
  • Seafloor vertical deformation

ASJC Scopus subject areas

  • Oceanography
  • Geophysics
  • Geochemistry and Petrology

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