Letter | Published:

Seafloor geodetic constraints on interplate coupling of the Nankai Trough megathrust zone

Nature volume 534, pages 374377 (16 June 2016) | Download Citation


Interplate megathrust earthquakes have inflicted catastrophic damage on human society. Such an earthquake is predicted to occur in the near future along the Nankai Trough off southwestern Japan—an economically active and densely populated area in which megathrust earthquakes have already occurred1,2,3,4,5. Megathrust earthquakes are the result of a plate-subduction mechanism and occur at slip-deficit regions (also known as ‘coupling’ regions)6,7, where friction prevents plates from slipping against each other and the accumulated energy is eventually released forcefully. Many studies have attempted to capture distributions of slip-deficit rates (SDRs) in order to predict earthquakes8,9,10. However, these studies could not obtain a complete view of the earthquake source region, because they had no seafloor geodetic data. The Hydrographic and Oceanographic Department of the Japan Coast Guard (JHOD) has been developing a precise and sustainable seafloor geodetic observation network11 in this subduction zone to obtain information related to offshore SDRs. Here, we present seafloor geodetic observation data and an offshore interplate SDR-distribution model. Our data suggest that most offshore regions in this subduction zone have positive SDRs. Specifically, our observations indicate previously unknown regions of high SDR that will be important for tsunami disaster mitigation, and regions of low SDR that are consistent with distributions of shallow slow earthquakes and subducting seamounts. This is the first direct evidence that coupling conditions might be related to these seismological and geological phenomena. Our findings provide information for inferring megathrust earthquake scenarios and interpreting research on the Nankai Trough subduction zone.

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  1. 1.

    Tectonic implications of the 1944 Tonankai and the 1946 Nankaido earthquakes, Japan. Phys. Earth Planet. Inter. 5, 129–139 (1972)

  2. 2.

    Source mechanism and tectonic significance of historical earthquakes along the Nankai Trough, Japan. Tectonophysics 27, 119–140 (1975)

  3. 3.

    & Coseismic slip resolution along a plate boundary megathrust: the Nankai Trough, southwest Japan. J. Geophys. Res. 104 (B1), 1111–1129 (1999)

  4. 4.

    & Contiguous rupture areas of two Nankai Trough earthquakes revealed by high-resolution tsunami waveform inversion. Geophys. Res. Lett. 32, L08305 (2005)

  5. 5.

    Central Disaster Management Council of the Japanese Government. (in Japanese; accessed 27 April 2015)

  6. 6.

    , & 2010 Maule earthquake slip correlates with pre-seismic locking of Andean subduction zone. Nature 467, 198–202 (2010)

  7. 7.

    , & Deformation cycles of subduction earthquakes in a viscoelastic Earth. Nature 484, 327–332 (2012)

  8. 8.

    & Spatiotemporal distribution of interplate coupling in southwest Japan from inversion of geodetic data. J. Geophys. Res. 109, B02315 (2004)

  9. 9.

    , & Dynamic rupture scenarios of anticipated Nankai-Tonankai earthquakes, southwest Japan. J. Geophys. Res. 116, B12319 (2011)

  10. 10.

    & Interplate coupling along the Nankai Trough, southwest Japan, inferred from inversion analyses of GPS data: effects of subducting plate geometry and spacing of hypothetical ocean-bottom GPS stations. Tectonophysics 600, 165–174 (2013)

  11. 11.

    & Centimeter-level positioning on the seafloor. Proc. Jpn Acad. B 77, 7–12 (2001)

  12. 12.

    et al. Interseismic seafloor crustal deformation immediately above the source region of anticipated megathrust earthquake along the Nankai Trough, Japan. Geophys. Res. Lett. 39, L10306 (2012)

  13. 13.

    et al. Precise GPS/acoustic positioning of seafloor reference points for tectonic studies. Phys. Earth Planet. Inter. 108, 101–112 (1998)

  14. 14.

    , & Measuring the onset of locking in the Peru-Chile trench with GPS and acoustic measurements. Nature 434, 205–208 (2005)

  15. 15.

    et al. Heterogeneous interplate coupling along the Nankai Trough, Japan, detected by GPS-acoustic seafloor geodetic observation. Prog. Earth Planet. Sci. 2, 10 (2015)

  16. 16.

    , , , & ITRF2005: a new release of the International Terrestrial Reference Frame based on time series of station positions and Earth Orientation Parameters. Geophys. J. Int. 112, B09401 (2007)

  17. 17.

    , & Geologically current plate motions. Geophys. J. Int. 181, 1–80 (2010)

  18. 18.

    et al. Coseismic slip distribution of the 2011 off the Pacific Coast of Tohoku Earthquake (M9.0) refined by means of seafloor geodetic data. J. Geophys. Res. 117, B07409 (2012)

  19. 19.

    & Viscoelastic relaxation following subduction earthquakes and its effects on afterslip determination. J. Geophys. Res. 120, 1329–1344 (2015)

  20. 20.

    & Geodetic data inversion using a Bayesian information criterion for spatial distribution of fault slip. Geophys. J. Int. 109, 363–375 (1992)

  21. 21.

    , , , & Subducted seamount imaged in the rupture zone of the 1946 Nankaido earthquake. Science 289, 104–106 (2000)

  22. 22.

    , , , & A subducted oceanic ridge influencing the Nankai megathrust earthquake rupture. Earth Planet. Sci. Lett. 217, 77–84 (2004)

  23. 23.

    et al. Imaging of the subducted Kyushu-Palau Ridge in the Hyuga-nada region, western Nankai Trough subduction zone. Tectonophysics 589, 90–102 (2013)

  24. 24.

    National Research Institute for Earth Science and Disaster Prevention. Activity of very-low-frequency earthquakes in and around Japan (November, 2014–May, 2015). Report of the Coordinating Committee for Earthquake Prediction, Japan (in Japanese) 94, 5–7 (2015)

  25. 25.

    , , , & Heterogeneous coupling of the Sumatran megathrust constrained by geodetic and paleogeodetic measurements. J. Geophys. Res. 113, B05305 (2008)

  26. 26.

    et al. Seismic and aseismic slip on the Central Peru megathrust. Nature 465, 78–81 (2010)

  27. 27.

    et al. Slow earthquakes linked along dip in the Nankai subduction zone. Science 330, 1502 (2010)

  28. 28.

    et al. Migrating tremor off southern Kyushu as evidence for slow slip of a shallow subduction interface. Science 348, 676–679 (2015)

  29. 29.

    et al. Preceding, coseismic, and postseismic slips of the 2011 Tohoku earthquake, Japan. J. Geophys. Res. 117, B07404 (2012)

  30. 30.

    in GPS for Geodesy, 2nd edn (eds & ) 537–567 (Springer, 1998)

  31. 31.

    Suboceanic geodetic measurements. IEEE Trans. Geosci. Remote Sensing GE-23, 502–510 (1985)

  32. 32.

    et al. Interplate coupling off northeastern Japan before the 2011 Tohoku-oki earthquake, inferred from seafloor geodetic data. J. Geophys. Res. 118, 1–10 (2013)

  33. 33.

    et al. Displacement above the hypocenter of the 2011 Tohoku-oki earthquake. Science 332, 1395 (2011)

  34. 34.

    et al. Evidence of viscoelastic deformation following the 2011 Tohoku-oki earthquake revealed from seafloor geodetic observation. Geophys. Res. Lett. 41, 5789–5796 (2014)

  35. 35.

    et al. GPS/acoustic seafloor geodetic observation: method of data analysis and its application. Earth Planets Space 58, 265–275 (2006)

  36. 36.

    , & Development of multi-epoch method for determining seafloor station position. Rep. Hydrograph. Oceanograph. Res. 26, 16–22 (2008; in Japanese).

  37. 37.

    et al. Improvement of GPS/acoustic seafloor positioning precision through controlling the ship’s track line. J. Geodesy 87, 825–842 (2013)

  38. 38.

    , & Continuous GPS array and present-day crustal deformation of Japan. Pure Appl. Geophys. 157, 2303–2322 (2000)

  39. 39.

    , , , & Trench-normal variation in observed seafloor displacements associated with the 2011 Tohoku-Oki earthquake. Geophys. Res. Lett. 38, L24303 (2011)

  40. 40.

    et al. Prevalence of viscoelastic relaxation after the 2011 Tohoku-oki earthquake. Nature 514, 84–87 (2014)

  41. 41.

    in Bayesian Statistics (eds , , & ) 143–166 (Valencia Univ. Press, 1980)

  42. 42.

    , & 3-D modelling of plate interfaces and numerical simulation of long-term crustal deformation in and around Japan. Pure Appl. Geophys. 161, 2053–2068 (2004)

  43. 43.

    & Geodetic imaging of plate motions, slip rates, and partitioning of deformation in Japan. J. Geophys. Res. 115, B02410 (2010)

  44. 44.

    , , , & Splay fault branching along the Nankai subduction zone. Science 297, 1157–1160 (2002)

  45. 45.

    et al. Three-dimensional splay fault geometry and implications for Tsunami generation. Science 318, 1128–1131 (2007)

  46. 46.

    , & Spatiotemporal distribution of very-low frequency earthquakes in Tokachi-oki near the junction of the Kuril and Japan trenches revealed by using array signal processing. Earth Planets Space 60, 871–875 (2008)

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We thank R. Burgmann and J.-P. Avouac for reviews of, and comments on, the manuscript. We thank O.L. Colombo of the NASA Goddard Space Flight Center for the kinematic GPS software IT (Interferometric Translocation)30, and the Geospatial Information Authority of Japan (GSI) for high-rate GPS data for kinematic GPS analysis, and for daily coordinates of the sites on the GSI website. T. Iinuma and T. Sun calculated the coseismic and postseismic deformations, respectively, of the 2011 Tohoku-oki earthquake. Comments from K. Wang and A. Kato improved our manuscript. We thank T. Yabuki of the JHOD for the Bayesian inversion software. Additionally, many among the staff of the JHOD—including the crew of the vessels Shoyo, Takuyo, Meiyo and Kaiyo—have supported our observations and data processing. Some figures were produced using GMT software, developed by P. Wessel and W. H. F. Smith.

Author information


  1. Hydrographic and Oceanographic Department, Japan Coast Guard, 3-1-1, Kasumigaseki, Chiyoda-ku, Tokyo 100-8932, Japan

    • Yusuke Yokota
    • , Tadashi Ishikawa
    • , Shun-ichi Watanabe
    •  & Toshiharu Tashiro
  2. Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan

    • Akira Asada


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Y.Y. carried out the inversion analysis. T.I. designed the study and performed the statistical processing. Y.Y. and S.W. performed the resolution tests. Y.Y., T.I., S.W. and T.T. processed the GPS-A seafloor geodetic data. A.A. constructed the GPS-A system.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Yusuke Yokota.

Extended data

Supplementary information

Excel files

  1. 1.

    Supplementary Table 1

    This file contains estimated relative site positions. The reference frame is ITRF2005. Eastward and Northward components indicate the data corrected the coseismic and postseismic effects due to the Tohoku-oki earthquake. Eastraw and Northraw components are raw data after March 2011.

  2. 2.

    Supplementary Table 2

    This table shows the position and calculated SDR value of each subfault in the inversion analysis. First and second columns show location (longitude and latitude) of each subfault. Third and fourth columns show angle (from the east to the counterclockwise direction) and absolute SDR value (m/year) calculated for each subfault in the inversion.

  3. 3.

    Supplementary Table 3

    This table contains observed and calculated vectors of each site in the inversion analysis. First and second columns show location (longitude and latitude) of each site. Third and fourth columns show angle (from the east to the counterclockwise direction) and absolute velocity value (m/year) observed in each site. Fifth and sixth columns show angle and absolute velocity value calculated for each site in the inversion.

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