Wide-angle seismic profiling of oceanic island arc in the southern Izu-Ogasawara arc –KY0502 cruise–

抄録

We carried out a deep wide-angle seismic experiment using a large airgun array and 110 ocean-bottom seismographs (OBSs) in the southern Izu-Ogasawara arc area. The experiment was conducted on the R/V Kaiyo of the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) from 12 February to 11 March 2005 (KY05-02 cruise). Objectives of this cruise were to determine the velocity structure of the entire arc-backarc system and the difference of crustal structures formed in the Oligocene, Eocene and the present to elucidate crustal growth. An airgun-OBS seismic line was set from the Izu-Ogasawara Trench near Chichijima to the Shikoku Basin across the southern Izu-Ogasawara arc in the arc-backarc system. The OBSs and a 12-channel hydrophone streamer recorded seismic signals, which were shot using a large airgun array with total capacity of 12,000 cubic inches. In this paper, we summarize information of the seismic experiments and introduce OBS data and reflection data.