Seafloor geodetic observations to reveal co- and postseismic slip distributions of the 2011 Tohoku-Oki earthquake

Fumiaki Tomita, Yusaku Ohta, Takeshi Iinuma, Ryota Hino, Motoyuki Kido, Naoki Uchida

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

The 2011 Tohoku-Oki earthquake (M9.0) occurred on March 11, 2011. Many studies have investigated the co-seismic slip distribution of the earthquake on the plate interface based on terrestrial seismological and geodetic data and seafloor geodetic data. However, since seafloor stations installed before the main shock were concentrated in the off Miyagi Prefecture area, the spatial extent of the area of very large slip on the shallow plate interface was not well constrained along the direction parallel to the Japan Trench. After the main shock, large post-seismic deformations were detected by the terrestrial Global Navigation Satellite System (GNSS) observation stations and the seafloor station network, which includes 20 new seafloor stations installed after the 2011 Tohoku-Oki earthquake. The post-seismic displacement rate field in the offshore area revealed that the viscoelastic relaxation in the asthenospheric layer beneath the earth’s elastic crust is the main cause of the post-seismic deformation not the afterslip on the plate interface. Since stress perturbation due to the co-seismic slip excited the viscoelastic relaxation, the post-seismic displacement rates provide information about the co-seismic slip. Therefore, it is possible to constrain the co-seismic slip distribution on the shallow plate interface near the Japan Trench, based on the post-seismic displacements by applying Green’s function, which includes viscoelastic displacement evolution. We simultaneously inverted co- and post-seismic displacement data to estimate the co- and post-seismic slip distributions of the 2011 Tohoku-Oki earthquake with better spatial resolution than models based on the elastic Green’s function. The result indicates that the shallow co-seismic rupture extended maximally from 37.0°N to 39.2°N near the Japan Trench. Afterslip distribution was also well constrained in comparison to previous studies because of the introduction of the newly established GNSS-Acoustic observation network.

Original languageEnglish
Title of host publication2018 OCEANS - MTS/IEEE Kobe Techno-Oceans, OCEANS - Kobe 2018
PublisherInstitute of Electrical and Electronics Engineers Inc.
ISBN (Electronic)9781538616543
DOIs
Publication statusPublished - 2018 Dec 4
Event2018 OCEANS - MTS/IEEE Kobe Techno-Oceans, OCEANS - Kobe 2018 - Kobe, Japan
Duration: 2018 May 282018 May 31

Publication series

Name2018 OCEANS - MTS/IEEE Kobe Techno-Oceans, OCEANS - Kobe 2018

Other

Other2018 OCEANS - MTS/IEEE Kobe Techno-Oceans, OCEANS - Kobe 2018
CountryJapan
CityKobe
Period18/5/2818/5/31

Keywords

  • 2011 Tohoku-Oki earthquake
  • Afterslip
  • GNSS-Acoustic observation
  • Post-seismic deformation
  • Viscoelastic relaxation

ASJC Scopus subject areas

  • Computer Networks and Communications
  • Oceanography
  • Space and Planetary Science
  • Energy Engineering and Power Technology
  • Ocean Engineering
  • Acoustics and Ultrasonics
  • Instrumentation

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    Tomita, F., Ohta, Y., Iinuma, T., Hino, R., Kido, M., & Uchida, N. (2018). Seafloor geodetic observations to reveal co- and postseismic slip distributions of the 2011 Tohoku-Oki earthquake. In 2018 OCEANS - MTS/IEEE Kobe Techno-Oceans, OCEANS - Kobe 2018 [8559370] (2018 OCEANS - MTS/IEEE Kobe Techno-Oceans, OCEANS - Kobe 2018). Institute of Electrical and Electronics Engineers Inc.. https://doi.org/10.1109/OCEANSKOBE.2018.8559370