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Development of Buried Sensor for Mobile Ocean Bottom Broadband Seismic Observation of the Next Generation

下一代移动海底宽带地震观测埋地传感器的开发

基本信息

批准号：
14340130
负责人：
KANAZAWA Toshihiko
金额：
$ 9.73万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

Since 1999, we have already developed the mobile broadband ocean bottom seismometer (BBOBS), and many practical observations in the northwestern Pacific Ocean and French Polynesian Sea have been conducted. But, through the evaluation of the seismic data, the noise level of horizontal components in long periods, those are important in data analyses, is rather high in average and its variation in time is also large. The reason of this high noise level is assumed as the small tilt variation of the large housing sphere due to a bottom current with time variation. To clear this problem, one idea of observation without the tilt variation is the use of small and low profile broadband sensor that enables to intrude into the sediment. Now, we developed a prototype of this next generation BBOBS (BBOBS-NX). In June 2008, we made a first step for it during the cruise of the R/V Kairei (JAMSTEC) with the ROV, Kaiko 7000II. It is a practical test to know achievement of the noise reduction with the idea above under support of the ROV. The prototype of BBOBS-NX was loaded on the ROV, and was located nearby the BBOBS that has already deployed in 2007. The sensor unit of BBOBS-NX was separated from the recording unit, and the sensor was pushed into the sediment. The OBDC had been dropped before the dive of the ROV, and was moved to nearby of them. The distance from the BBOBS to the BBOBS-NX is about 10m. We will recover these instruments several months later to get enough length of data to evaluate correcty

自1999年以来，我们已研制出移动宽带海底地震仪（BBOBS），并在西北太平洋和法属波利尼西亚海进行了多次实际观测。但通过对地震资料的评价，资料分析中重要的长周期水平分量的噪声水平平均较高，且随时间变化也较大。这种高噪声水平的原因被认为是由于底部电流随时间变化而导致大外壳球体的小倾斜变化。为了解决这个问题，一种在没有倾斜变化的情况下进行观测的想法是使用小型且薄型的宽带传感器，该传感器能够侵入沉积物。现在，我们开发了下一代 BBOBS (BBOBS-NX) 的原型。 2008年6月，我们在R/V Kairei（JAMSTEC）搭载ROV Kaiko 7000II的巡航中迈出了第一步。通过上述思路在ROV的支持下降噪效果如何，是一个实际的测试。 BBOBS-NX的原型机装载在ROV上，位于2007年已经部署的BBOBS附近。BBOBS-NX的传感器单元与记录单元分离，传感器被推入沉积物中。 OBDC 在 ROV 下潜之前已被丢弃，并被移至其附近。 BBOBS到BBOBS-NX的距离约为10m。我们将在几个月后恢复这些仪器，以获得足够长度的数据来评估正确性