Skip to main content

Seismic structure of the northern end of the Ryukyu Trench subduction zone, southeast of Kyushu, Japan

Abstract

P-wave velocity models related to the Philippine Sea plate subduction have been obtained from seismic explorations at the northern end of the Nansei-Shoto (Ryukyu) Trench. Both multi-channel seismic reflection and ocean bottom seismographic records provide clear images of the rough seafloor topography and irregular P-wave velocity structure of the northwestern extension of the Kyushu-Palau Ridge and Amami Plateau below the landward trench slope. Low velocity (V p ≤ 4–5 km/s) and thick (>7 km) materials above the plate boundary characterize the landward trench slope structure. An exception to this is found where the subducting plate contacts higher velocity (V p > 5 km/s) materials of the landward plate at the estimated position of the seismic asperity of 1968 Hyuganada earthquake (Mw 7.5).

References

  • Fujie, G., J. Kasahara, T. Sato, and K. Mochizuki, Traveltime and raypath computation: A new method in a heterogeneous medium, J. Soc. Explor. Geophys. Jpn., 53, 1–11, 2000.

    Google Scholar 

  • Ichikawa, G., Ocean bottom seismographic experiment to study crustal structure in Hyuga-nada, Master’s Thesis, Hokkaido University, Sapporo, Japan, 1997 (in Japanese).

    Google Scholar 

  • Iwasaki, T. et al., Crustal and upper mantle structure in the Ryukyu Island Arc deduced from deep seismic sounding, Geophys. J. Int., 102, 631–651, 1990.

    Article  Google Scholar 

  • Kasahara et al., A new integrated method for the crustal structure analysis using OBSs and control sources, Eos Trans. AGU, 88(52), Fall Meet. Suppl., Abstract S12A–06, 2007.

    Google Scholar 

  • Kodaira, S., T. Iwasaki, T. Urabe, T. Kanazawa, F. Egloff, J. Makris, and H. Shimamura, Crustal structure across the middle Ryukyu trench obtained from ocean bottom seismographic data, Tectonophysics, 263, 39–60, 1996.

    Article  Google Scholar 

  • Korenaga, J., W. S. Holbrook, G. M. Kent, P. B. Kelemen, R. S. Detrick, H.-C. Larsen, J. R. Hopper, and T. Dahl-Jensen, Crustal structure of the southeast Greenland margin from joint refraction and reflection seismic tomography, J. Geophys. Res., 105, 21591–21614, 10.1029/2000JB900188, 2000.

    Article  Google Scholar 

  • Kubota, R., E. Nishiyama, K. Murase, and J. Kasahara, Traveltime estimation of first arrivals and later phases using the modified graph method for a crustal structure analysis, Explor. Geophys., 40, 105–113, 2009.

    Article  Google Scholar 

  • Larsen, S. C. and C. A. Schultz, ELAS3D: 2D/3D elastic finite-difference wave propagation code, LLNL internal report, 18 p., 1995.

    Google Scholar 

  • Nishizawa, A., K. Kaneda, Y. Katagiri, and J. Kasahara, Variation in crustal structure along the Kyushu-Palau Ridge at 15–21°N on the Philippine Sea plate based on seismic refraction profiles, Earth Planets Space, 59, e17–e20, 2007.

    Article  Google Scholar 

  • Nishizawa, A., K. Kaneda, N. Watanabe, and M. Oikawa, Seismic structure of the subducting seamounts on the trench axis: Erimo Seamount and Daiichi-Kashima Seamount, northern and southern ends of the Japan Trench, Earth Planets Space, 61, e5–e8, 2009.

    Article  Google Scholar 

  • Noda et al., Preliminary report of multi-channel and wide-angle seismic surveys at the northern Kyushu-Palau Ridge (KPr4), the Daito Ridge and Amami Plateau (DAr2) and the mid Shikoku Basin (SPr7), Technical Bull. Hydrogr. Oceanogr., 42, 2006 (in Japanese).

  • Oshida, A., R. Kubota, E. Nishiyama, J. Ando, J. Kasahara, A. Nishizawa, and K. Kaneda, A new method for determining OBS positions for crustal structure studies, using airgun shots and precise bathymetric data, Explor. Geophys., 39, 15–25, 2008.

    Article  Google Scholar 

  • Tanaka et al., Preliminary report of multi-channel and wide-angle seismic experiments in the vicinity of Kyushu-Palau Ridge (KPr1, KPr2 and SPr10) and traversing the Minami Daito Basin, Daito Ridge and Kyushu-Palau Ridge (DAr5), Technical Bull. Hydrogr. Oceanogr., 44, 2008 (in Japanese).

  • The Headquarters for Earthquake Research Promotion, Evaluations of occurrence potentials of subduction-zone earthquakes to date, http://www.jishin.go.jp/main/chousa/04febhyuganada/index.html, 2004 (in Japanese).

    Google Scholar 

  • Wessel, P. and W. H. F. Smith, New, improved version of the Generic MappingTools released, Eos Trans. AGU, 79, 579, 1998.

    Article  Google Scholar 

  • Yagi, Y., M. Kikuchi, S. Yoshida, and Y. Yamanaka, Source Process of the Hyuga-nada earthquake of April 1, 1968 (Mjma 7.5), and relationship to the subsequent seismicity, Zisin, 51, 139–148, 1998 (in Japanese with English abstract).

    Google Scholar 

Download references

Author information

Affiliations

Authors

Corresponding author

Correspondence to Azusa Nishizawa.

Rights and permissions

Open Access  This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made.

The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.

To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/.

Reprints and Permissions

About this article

Cite this article

Nishizawa, A., Kaneda, K. & Oikawa, M. Seismic structure of the northern end of the Ryukyu Trench subduction zone, southeast of Kyushu, Japan. Earth Planet Sp 61, e37–e40 (2009). https://doi.org/10.1186/BF03352942

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1186/BF03352942

Key words

  • Marine seismics
  • Ryukyu (Nansei Shoto) Trench
  • Kyushu-Palau Ridge
  • Philippine Sea plate subduction