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Research of a Next-Generation Laser Tsunami Measurement Network system

下一代激光海啸测量网络系统研究

基本信息

批准号：
11358005
负责人：
ITO Hiromasa
金额：
$ 23.81万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

项目摘要

An optical hydraulic-pressure gauge for an optical ocean bottom tsunami meter was developed using a frequency, shifted feedback laser with a rolled fiber sensor based on optical frequency domain reflectometry. Measuring the optical path length of the fiber, the hydraulic pressure is calculated. The sensor consisted of an 870 m-long bare dispersion-shifted fiber rolled on a hollow cylindrical aluminum bobbin, and its pressure sensitivity was confirmed as -2.34 10^<-11> /Pa. The accuracy of distance measurement was 10^<-9> using the frequency shifted feedback laser oscillating at 1.55 μm. Then the accuracy of pressure measurement using this system was 62 Pa, which corresponds to a depth of 6.2 mm and is sufficient performance for tsunami-measurement applications.Moreover, an origin with a field-spread of a tsunami was estimated using the reverse propagation technique analysis. This draws the wave crest lines to the maximum high-water level point and zero-cross point of the first wave of tsunami about each of two ocean bottom tsunami meters, and estimates the intersection as the origin area. As a result of carrying out a simulation about the tsunami network for the Pacific rim, by adding ocean bottom tsunami meters to the Hawaii Islands circumference realized that an origin area could be estimated with less than 20 % of error.On the coast of our country, human life is taken by tsunami and it is inflicting serious material damage frequently. It is indispensable to damage mitigation by tsunami offering exact information promptly. Real-time multi-point measurement is possible by the multiplexing the laser hydraulic pressure gauge using a frequency-shifted feedback laser. A tsunami numerical simulation can grasp correctly the scale and arrival time of tsunami. If the measurement network by the ocean bottom tsunami meter of a wide area based on this research result is realized, an exact tsunami warning can be issued and it is expected to minimize the damage.

研制了一种用于光学海底海啸仪的光学水压计，该仪器采用频移反馈激光器和基于光频域反射法的滚动光纤传感器。测量光纤的光程长度，计算液压压力。该传感器由一根870 m长的裸色散位移光纤卷绕在空心圆柱形铝筒上组成，其压力灵敏度为-2.34 10^<-11>/Pa。采用<-9>频率为1.55 μm的移频反馈激光器，测距精度可达10 μm。然后，使用该系统的压力测量精度为62 Pa，这对应于6.2 mm的深度，是足够的性能用于海啸测量应用。此外，使用反向传播技术分析，估计了海啸的场传播的起源。这两个海底海啸仪的每一个都绘制到最大高水位点和第一波海啸的零交叉点的波峰线，并将交叉点估计为起源区域。通过对环太平洋地区海啸网络的模拟，在夏威夷群岛周边增加海底海啸仪，可以实现对海啸起源区域的估计，误差小于20%。在我国沿海，海啸夺去了人们的生命，并经常造成严重的物质损失。及时提供准确的海啸信息对减轻海啸灾害是必不可少的。采用频移反馈激光器对激光液压计进行多路复用，可实现实时多点测量。海啸数值模拟可以准确把握海啸的规模和到达时间。如果基于该研究成果的大范围海底海啸计的测量网络得以实现，就可以发出准确的海啸警报，并有望将损失降至最低。