HR: 0800h
AN: G51B-0826    [Abstracts]
TI: GPS/Acoustic seafloor positioning off the northeastern Japan
AU: Fujimoto, H
EM: fujimoto@aob.geophys.tohoku.ac.jp
AF: Graduate School of Science, Tohoku University, Aoba-ku, Sendai, 9808578 Japan
AU: * OSADA, Y
EM: osada@aob.geophys.tohoku.ac.jp
AF: Graduate School of Science, Tohoku University, Aoba-ku, Sendai, 9808578 Japan
AU: MIZUKAMI, T
EM: mizu@aob.geophys.tohoku.ac.jp
AF: Graduate School of Science, Tohoku University, Aoba-ku, Sendai, 9808578 Japan
AU: MIURA, S
EM: miura@aob.geophys.tohoku.ac.jp
AF: Graduate School of Science, Tohoku University, Aoba-ku, Sendai, 9808578 Japan
AU: Fujita, M
EM: masayuki-fujita@kaiho.mlit.go.jp
AF: Hydrographic and Oceanographic Department, Japan Coast Guard, 5-3-1 Tsukiji, Chuo-ku, Tokyo, 040045 Japan
AU: ISHIKAWA, T
EM: tadashi-ishikawa@kaiho.mlit.go.jp
AF: Hydrographic and Oceanographic Department, Japan Coast Guard, 5-3-1 Tsukiji, Chuo-ku, Tokyo, 040045 Japan
AB: Our group has developed a seafloor positioning system combining kinematic GPS (KGPS) and precise underwater acoustic ranging to investigate dynamics of the plate boundary on Japan Trench. We use a small towed buoy for the positioning, and successfully reduce the effect of underwater acoustic noises generated from a survey vessel. We developed a precise underwater acoustic ranging system for medium water depth up to 3000m, which is simple enough to use an acoustic signal with a single frequency of 10 kHz. We observed the seafloor crustal movement using repeating observation of the GPS/Acoustic system. In 2005 Aug 16, it occurred the 2005 Miyagi-oki earthquake (Mj 7.2). We can observe the GPS/A observation before and after this earthquake. In this poster we present a results of experiments carried out off the coast of Miyagi Prefecture in the Japan Trench subduction among 2003 and 2005. At first, we estimate the positions of each PXP using data collected while the buoy shifted around each PXP during a cruise in August 2003 on one site. We determine the center of the PXP array using the data collected near the array center. The number of shots which can be used in the analysis of data in 2003 was only 14 for shortage of the observation period. We relocate the center of the PXP array using the data collected near the array center at a cruise in August 2004 and June 2005. We estimate the position of the array center to be 3.9+/-8.7cm in latitude, 5.1+/-11.2cm in longitude on August 2004. We estimate the position of the array center on June 2005. At other two sites, we started the observation in 2005. We estimate the position of the array center to be +/- 10cm in longitude and latitude of At other two sites, we started the observation in 2005. We estimate the position of the array center to be +/- 10cm in longitude and latitude of the standard deviation on June 2005. In next step we relocate the center of the PXP array using the data collected near the array center at a cruise in Aug 2005.
DE: 1209 Tectonic deformation (6924)
DE: 1294 Instruments and techniques
SC: Geodesy [G]
MN: Fall Meeting 2005