Thursday 25 August 2005

G6
1330-1530 hours

394
Development of a new tsunami monitoring system using a GPS buoy
Kato, Teruyuki¹, Terada, Yukihiro², Ito, Keiji², Fujita, Takashi², Hattori, Ryuji², Abe, Takenori², Miyake, Toshihide², Koshimura, Shun'ichi³, Nagai, Toshihiko⁴
1 Earthquake Research Institute, Univ. Tokyo, Japan
2 Technical Research Institute, Hitachi Zosen Corporation, Japan
3 School of Engineering, Tohoku University, Japan
4 Port and Airport Research Institute, Japan
Author email: teru@eri.u-tokyo.ac.jp
Monitoring of tsunami at distant offshore of the nearby coast would be an effective measure for mitigating disaster due to tsunami. We have developed a new tsunami monitoring system using a GPS buoy, for this purpose, by applying Real-time kinematic (RTK) GPS technology. After the success of a three year experiment at offshore of Ofunato City, northeastern Japan, we newly designed a buoy for more operational use. It was established about 12km south of Muroto Promontory on April 11, 2004. The buoy is about 16 meters of height, 3.4m in diameter and 17 tons of weight. The buoy not only equips GPS antenna but also other meteorological and oceanographic sensors, so that it may be used as a synthetic meteorological/oceanographic instrument. The processed record is disseminated through webpage with about 30seconds of delay. On September 5th 2004, a large earthquake occurred about 300km east of the buoy. The buoy successfully detected the tsunami generated by this earthquake. The recorded tsunami showed about ten centimeters of initial height. The observed temporal change of sea surface due to tsunami showed excellent consistency with predicted change based on numerical simulation. It shows that that the GPS buoy may be capable of detecting tsunami about 8-10 minutes prior to its arrival to the coast.

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