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.
|Number of pages||39|
|Journal||Science Reports of the Kyushu University, Department of Earth and Planetary Sciences|
|Publication status||Published - Jan 1 2004|
ASJC Scopus subject areas
- Space and Planetary Science
- Earth and Planetary Sciences(all)