Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

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


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.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Rent or buy this article

Prices vary by article type



Prices may be subject to local taxes which are calculated during checkout

Figure 1: Seafloor velocity field, based on seafloor geodetic observations at 15 seafloor sites along the Nankai Trough.
Figure 2: Interplate SDR distribution as indicated by onshore and seafloor geodetic data.


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

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

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

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

    Article  CAS  PubMed  ADS  Google Scholar 

  7. Wang, K., Hu, Y. & He, J. Deformation cycles of subduction earthquakes in a viscoelastic Earth. Nature 484, 327–332 (2012)

    Article  CAS  PubMed  ADS  Google Scholar 

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

    ADS  Google Scholar 

  9. Hok, S., Fukuyama, E. & Hashimoto, C. Dynamic rupture scenarios of anticipated Nankai-Tonankai earthquakes, southwest Japan. J. Geophys. Res. 116, B12319 (2011)

    Article  ADS  Google Scholar 

  10. Yoshioka, S. & Matsuoka, Y. 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)

    Article  ADS  Google Scholar 

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

    Article  Google Scholar 

  12. Tadokoro, K. 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)

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  14. Gagnon, K., Chadwell, C. D. & Norabuena, E. Measuring the onset of locking in the Peru-Chile trench with GPS and acoustic measurements. Nature 434, 205–208 (2005)

    Article  CAS  PubMed  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  16. Altamimi, Z., Collilieux, X., Legrand, J., Garayt, B. & Boucher, C. 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)

    ADS  Google Scholar 

  17. DeMets, C., Gordon, R. G. & Argus, D. F. Geologically current plate motions. Geophys. J. Int. 181, 1–80 (2010)

    Article  ADS  Google Scholar 

  18. Iinuma, T. 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)

    Article  Google Scholar 

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

    Article  ADS  Google Scholar 

  20. Yabuki, T. & Matsu’ura, M. Geodetic data inversion using a Bayesian information criterion for spatial distribution of fault slip. Geophys. J. Int. 109, 363–375 (1992)

    Article  ADS  Google Scholar 

  21. Kodaira, S., Takahashi, N., Nakanishi, A., Miura, S. & Kaneda, Y. Subducted seamount imaged in the rupture zone of the 1946 Nankaido earthquake. Science 289, 104–106 (2000)

    Article  CAS  PubMed  ADS  Google Scholar 

  22. Park, J.-O., Moore, G. F., Tsuru, T., Kodaira, S. & Kaneda, Y. A subducted oceanic ridge influencing the Nankai megathrust earthquake rupture. Earth Planet. Sci. Lett. 217, 77–84 (2004)

    Article  CAS  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  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. Chlieh, M., Avouac, J. P., Sieh, K., Natawidjaja, D. H. & Galetzka, J. Heterogeneous coupling of the Sumatran megathrust constrained by geodetic and paleogeodetic measurements. J. Geophys. Res. 113, B05305 (2008)

    Article  ADS  Google Scholar 

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

    Article  CAS  PubMed  ADS  Google Scholar 

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

    Article  CAS  PubMed  ADS  Google Scholar 

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

    Article  CAS  PubMed  ADS  Google Scholar 

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

    Article  Google Scholar 

  30. Colombo, O. L. in GPS for Geodesy, 2nd edn (eds Kleusberg, A. & Teunissen, P. ) 537–567 (Springer, 1998)

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

    Article  ADS  Google Scholar 

  32. Sato, M. 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)

    Article  Google Scholar 

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

    Article  CAS  PubMed  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

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

    Google Scholar 

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

    Article  ADS  Google Scholar 

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

    ADS  Google Scholar 

  39. Kido, M., Osada, Y., Fujimoto, H., Hino, R. & Ito, Y. Trench-normal variation in observed seafloor displacements associated with the 2011 Tohoku-Oki earthquake. Geophys. Res. Lett. 38, L24303 (2011)

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

    Article  CAS  PubMed  ADS  Google Scholar 

  41. Akaike, H. in Bayesian Statistics (eds Bernardo, J. M., DeGroot, M. H., Lindley, D. V. & Smith, A. F. M. ) 143–166 (Valencia Univ. Press, 1980)

  42. Hashimoto, C., Fukui, K. & Matsu’ura, M. 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)

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  44. Park, J.-O., Tsuru, T., Kodaira, S., Cummins, P. R. & Kaneda, Y. Splay fault branching along the Nankai subduction zone. Science 297, 1157–1160 (2002)

    Article  CAS  PubMed  ADS  Google Scholar 

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

    Article  CAS  PubMed  ADS  Google Scholar 

  46. Asano, Y., Obara, K. & Ito, Y. 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)

    Article  ADS  Google Scholar 

Download references


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

Authors and Affiliations



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.

Corresponding author

Correspondence to Yusuke Yokota.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Extended data figures and tables

Extended Data Figure 1 Our GPS-A seafloor geodetic observation system.

The system, comprising on-board and seafloor sensors, was developed as described in ref. 11 and improved as described in ref. 35. This diagram was modified from refs 15, 34, 37. CTD, conductivity temperature depth profiler; XCTD, expendable conductivity temperature depth profiler; XBT, expendable bathythermographs.

Extended Data Figure 2 Horizontal movements of seafloor sites over time.

Time series for east–west (left column) and north–south (right column) displacements of seafloor sites TOK1, TOK2, TOK3, KUM1, KUM2 and KUM3 from 2006 onwards. The position reference is the Amur plate. Blue circles indicate raw observations before deductions of the coseismic and postseismic effects that resulted from the magnitude-9.0 Tohoku-oki earthquake of 11 March 2011. Red circles indicate the corrected final results. The linear trends and the 95% two-sided confidence intervals are shown with red solid and dashed lines, respectively. Grey lines show the calculated coseismic and postseismic deformations following the Tohoku-oki earthquake18,19.

Extended Data Figure 3 Horizontal movements of seafloor sites over time.

Time series showing east–west (left column) and north–south (right column) displacements of seafloor sites SIOW, MRT1, MRT2, TOS1, TOS2 and ASZ1. Colours are as in Extended Data Fig. 2.

Extended Data Figure 4 Horizontal movements of seafloor sites over time.

Time series showing east–west (left column) and north–south (right column) displacements of seafloor sites ASZ2, HYG1 and HYG2. Colours are as in Extended Data Fig. 2.

Extended Data Figure 5 Comparison of calculated SDR distributions obtained using onshore data only versus onshore plus seafloor data.

a, b, SDR distributions (for SDRs of more than 2 cm year−1) calculated using only onshore data (a) or using onshore and seafloor data (b). Black and white vectors indicate the observed data and the calculated velocities, respectively. Grey shading indicates areas with resolution values lower than 0.05 (calculated in Extended Data Fig. 6d, e). α is the hyperparameter of smoothness.

Extended Data Figure 6 Checkerboard resolution tests and distributions of resolution values.

a–c, Results of checkerboard resolution tests for the SDR inversions. a, Input checkerboard-like SDR distribution. b, c, The checkerboard distributions calculated from using onshore data only (b) or using both onshore and seafloor data (c). d, e, Resolution values as diagonal elements of the resolution matrix, calculated using onshore data only (d) or using onshore and seafloor data (e). Black and blue dots denote the onshore and seafloor sites, respectively, used in each calculation. α is the hyperparameter of smoothness.

Extended Data Figure 7 Examination of boundary condition effects.

a–c, Estimated SDR distributions (for SDRs of more than 2 cm year−1) calculated with a, the free condition; b, zero backslip at all boundaries; and c, a 6.5 cm year−1 constraint at the south edge (the other boundaries being in the free condition). Grey shading indicates areas with resolution values lower than 0.05, calculated in Extended Data Fig. 6e. α is the hyperparameter of smoothness.

Extended Data Figure 8 Events determined using analysis of automatic VLFE detection24.

Purple and blue dots denote events in the periods 1 June 2003 to 10 May 2015, and 1 August 2008 to 10 May 2015, respectively. Grey stars indicate epicentres of the 2004 earthquakes off the Kii Peninsula. Pale green lines indicate the depths of the plate boundary determined using the CAMP model42.

Supplementary information

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. (XLSX 18 kb)

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. (XLSX 19 kb)

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. (XLSX 21 kb)

PowerPoint slides

Rights and permissions

Reprints and Permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Yokota, Y., Ishikawa, T., Watanabe, Si. et al. Seafloor geodetic constraints on interplate coupling of the Nankai Trough megathrust zone. Nature 534, 374–377 (2016).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing