Research report of the crust and upper mantle structure in the Okinawa Trough, off west Kyushu by using ocean bottom seismometers

Kazou Nakahigashi, Masanao Shinohara, Sadaomi Suzuki, Hiroshi Takenaka, Nobuki Kame, Kenji Uehira, Hajime Shiobara, Toshihiko Kanazawa, Ryota Hino, Minoru Nishino, Takeshi Sato, Shinji Yoneshima

Research output: Contribution to journalArticle

Abstract

The Okinawa Trough is located in the back-arc region of the Ryukyu Island arc, and is considered to be an active spreading area. In fall of 1999, seismic survey using ocean bottom seismometers was conducted to obtain the detailed seismic structure in the northernmost part of the Okinawa Trough. The total crust thickness is 25 km including a sedimentary layer. The velocity of the upper crust changes from 5.7-6.0 km/s in the upper part to 6.1-6.2 km/s in the lower part. And its thickness changes from 3 km to 9 km. The lower crust of which velocity slightly changes from 6.5-6.7 km/s in the upper part to 6.8-6.9 km/s in the lower part has uniform thickness of about 15 km. The Pn velocity is determined to be 7.7-7.8 km/s. The seismic structure suggests that the northernmost part of the Okinawa Trough is in the incipient stage of a backarc rifting.

Original languageEnglish
Pages (from-to)69-107
Number of pages39
JournalScience Reports of the Kyushu University, Department of Earth and Planetary Sciences
Volume21
Issue number3
Publication statusPublished - Jan 1 2004
Externally publishedYes

ASJC Scopus subject areas

  • Space and Planetary Science
  • Earth and Planetary Sciences(all)

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    Nakahigashi, K., Shinohara, M., Suzuki, S., Takenaka, H., Kame, N., Uehira, K., Shiobara, H., Kanazawa, T., Hino, R., Nishino, M., Sato, T., & Yoneshima, S. (2004). Research report of the crust and upper mantle structure in the Okinawa Trough, off west Kyushu by using ocean bottom seismometers. Science Reports of the Kyushu University, Department of Earth and Planetary Sciences, 21(3), 69-107.