Development of a tsunami detection system using RTK-GPS

我们开发了一个使用RTK-GPS技术的海啸探测系统。RTK-GPS是利用全球定位系统对移动平台进行实时定位的系统。首先，我们设计了一个浮标系统，由两个浮标组成;一个8米长的浮筒用于放置GPS天线，一个用于放置GPS接收器、PC、电池等的支撑浮标。这些浮标使用单根电缆拴系。我们在关东南部的相模湾进行了一项实验。两个浮标都锚定在海岸外约900米处，数据通过无线电传输。使用太阳能电池板和风力发电机的混合系统用于浮标上的电力供应。在数据传输到陆地后，RTK处理的数据在设置在实验室中的PC的显示器上进行监视。数据连续记录了十天左右，没有一秒钟的丢失。所获得的数据与放置在附近的验潮仪记录进行了比较。比较表明，估计的海平面有大约1cm的精度。然后，为了检查长期稳定性并检查环境稳健性，我们在大坂湾进行了约一年的实验。频率分析表明，风浪的影响是上级的范围内小于几秒钟，海啸的更长的周期可以检测滤波技术。因此，作为一个结论，实验是成功的，所提出的浮标系统可以用于海啸预警，因为它可以检测到海啸到达海岸之前。第二代海啸浮标目前在大船渡近海运行，供地方政府监测海啸。

We have developed a tsunami detection system using RTK-GPS technology. RTK-GPS is a real-time positioning system of moving platform using the Global Positioning System. First, we designed a buoy system that consists of two buoys; a spar type buoy of 8m long for putting a GPS antenna and a support buoy for putting GPS receivers, PC, butteries etc. These buoys are tethered using a single cable. We have conducted an experiment at the Sagami Bay, southern Kanto. Both of buoys were anchored about 900m offshore of the coast and the data were transmitted using radio. Hybrid system using solar panels and a wind generator was used for power supply on the buoy. After the transmission of data to land, the RTK processed data were monitored on the display of a PC that was set in the laboratory. The data was recorded continuously for about ten days without a single second of loss. The obtained data were compared with the tide gauge records placed nearby. The comparison suggested that the estimated sea-level has about 1cm accuracy. Then, in order to check the long-term stability and to examine the environmental robustness, we have conducted about one year of experiment in the Osaka bay. Frequency analysis of obtained data suggested that the effects of wind waves is superior in the range of less than several seconds and the longer period of tsunami could be detected by filtering technique. Thus, as a conclusion, the experiment was successful and the proposed buoy system may be utilized for tsunami warning because it can detect the arrival of tsunami before it reaches the coast. The second generation of tsunami-buoy is now operation offshore of Ofunato for monitoring at local government for watch tsunami.