HR: 0800h
AN: V21D-0759    [Abstracts]
TI: Hydrothermal fountains imaged by high resolution side-scan sonar equipped on a cruising AUV, URASHIMA
AU: * Kumagai, H
EM: kumagai@jamstec.go.jp
AF: IFREE, JAMSTEC, 2-15 Natsushima-cho, Yokosuka, 237-0061, Japan
AU: Tsukioka, S
EM: tsukiokas@jamstec.go.jp
AF: MARITEC, JAMSTEC, 2-15 Natsushima-cho, Yokosuka, 237-0061, Japan
AU: Yamamoto, H
EM: kyama@jamstec.go.jp
AF: XBR, JAMSTEC, 2-15 Natsushima-cho, Yokosuka, 237-0061, Japan
AU: Shitashima, K
EM: shita@criepi.denken.or.jp
AF: Ctrl Res Inst Elec Power Ind, 1646 Abiko, Abiko, 270-1194, Japan
AU: Yamamoto, F
EM: yamamotof@jamstec.go.jp
AF: CDEX, JAMSTEC, 3173-25 Showa-machi, Kanazawa-ku, Yokohama, 236-0001, Japan
AU: Sawa, T
EM: sawa@jamstec.go.jp
AF: MARITEC, JAMSTEC, 2-15 Natsushima-cho, Yokosuka, 237-0061, Japan
AU: Hyakudome, T
EM: hyaku@jamstec.go.jp
AF: MARITEC, JAMSTEC, 2-15 Natsushima-cho, Yokosuka, 237-0061, Japan
AU: Kasaya, T
EM: tkasa@jamstec.go.jp
AF: IFREE, JAMSTEC, 2-15 Natsushima-cho, Yokosuka, 237-0061, Japan
AU: Kinoshita, M
EM: masa@jamstec.go.jp
AF: IFREE, JAMSTEC, 2-15 Natsushima-cho, Yokosuka, 237-0061, Japan
AB: Mapping of an area and intensities of activity at a particular hydrothermal field has required huge effort so far, typically several tens of dives of manned submersibles and/or ROVs to obtain detailed locality map with needed resolutions. Thus, appropriate remote sensing techniques have been desired since the discovery of seafloor hydrothermal field. A series of successful trials has been performed by ABE of WHOI equipped with a Eh-sensor (Yoerger et al., Oceanography, 2007). A 100kHz side-scan sonar (SSS) equipped on a cruising AUV, URASHIMA, caught detailed structural image of hydrothermal fountains rooting active chimneys during YK07-07 Cruise off Okinawa Isl. (May 6-18, 2007). The URASHIMA AUV is a 10-m-length cylindrical-shaped one that originally optimized to long distance cruise. In the expedition, she cruised near the sea floor with 50-100 m altitude, at the area of 1000-1500 m in WD. She has currently basic oceanographic/CTD sensors, a 400kHz echo-sounder and sonars of 100\/400 kHz side-scan sonar and up to 6 kHz sub-bottom profiler. In this operation, pH and ORP sensors (CRIEPI) were also attached in front of AUV. On the pre-processing image of SSS, numbers of filament-shape echoes were recorded within water column zone. The reason why they should be the echo from hydrothermal plumes are as folows; 1) the echoes in the water column were limitedly recorded above the active hydrothermal field; 2) CTD and pH sensors show temperature and pH anomaly corresponding to the record of echoes; 3) some of the root of the filament-shape echoes correspond to the hydrothermal mound recognized in the detailed bathymetry obtained with SeaBat7125 MNBES. This-like technique should revolute the mapping work prior to the sampling at the particular hydrothermal site.
DE: 1034 Hydrothermal systems (0450, 3017, 3616, 4832, 8135, 8424)
DE: 3017 Hydrothermal systems (0450, 1034, 3616, 4832, 8135, 8424)
DE: 4832 Hydrothermal systems (0450, 1034, 3017, 3616, 8135, 8424)
DE: 8424 Hydrothermal systems (0450, 1034, 3017, 3616, 4832, 8135)
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting