| 西北太平洋海岛地区地震背景噪声特征及海洋学解释 |
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| 引用本文： | 陈栋炉,林建民,倪四道,祝翔宇,郑红.西北太平洋海岛地区地震背景噪声特征及海洋学解释[J].地球物理学报,2018,61(1):230-241. |
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| 作者姓名： | 陈栋炉 林建民 倪四道 祝翔宇 郑红 |
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| 作者单位： | 1. 浙江海洋大学海洋科学与技术学院, 浙江舟山 316022;2. 中国科学院测量与地球物理研究所大地测量与地球动力学国家重点实验室, 武汉 430077;3. 宁波市海洋与渔业信息监测中心, 浙江宁波 315141 |
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| 基金项目： | 国家自然科学基金（41104027），浙江省自然科学基金重点项目（LZ14D060001），大地测量与地球动力学国家重点实验室开放基金（SKLGED2013-1-7-E）和中国科学院重要方向性项目（KZCX2-EW-121）共同资助. |
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| 摘 要： | 地震背景噪声特性及噪声源的分布研究逐渐成为深化背景噪声层析成像的关键问题.海岛地区由于特殊的地理位置，其背景噪声具有相对独特的特征.地脉动（约0.003~1 Hz）是地震背景噪声中能量最强的分量，其激发与特性被认为与海浪运动和固体地球之间的相互作用有关，但海岛地区地脉动特征与海洋波浪场之间的关系尚未被充分研究.本文利用西北太平洋海岛地震台站的连续记录数据、波浪浮标的实测数据以及WAVEWATCH-Ⅲ海浪模式的数值模拟结果，通过地震学和海洋学的交叉，分析海岛地区地脉动信号的时频特性及其与海洋波浪场之间的相关性，从海洋学角度对地脉动信号的特征及激发进行探讨与解释.结果表明，海岛地区地脉动信号相对于内陆地区更强，并具有明显且稳定的季节性变化特征：高频地脉动信号（0.12~0.32 Hz）在夏秋季节（5月-10月）相对较弱，而在冬春季节（11月-次年4月）相对较强，与北半球海洋活动季节性变化相一致.此外，海岛地区地脉动主要受周边海域波浪场影响，与周边海域波浪能功率密度及实测和数值模拟所得的有效波高均具有很好的互相关性.该研究结果同时表明可进一步发展利用地脉动观测数据反演海表波浪场的可能，为海洋科学研究中海表波浪场连续观测数据的获取提供地震学上的支持.
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| 关 键 词： | 海岛 地震背景噪声 地脉动 时频特性 海浪 台风 |
| 收稿时间： | 2017-01-16 |
Characteristics of seismic noise on ocean islands in Northwest Pacific and its oceanographic interpretation |
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| CHEN DongLu,LIN JianMin,NI SiDao,ZHU XiangYu,ZHENG Hong.Characteristics of seismic noise on ocean islands in Northwest Pacific and its oceanographic interpretation[J].Chinese Journal of Geophysics,2018,61(1):230-241. |
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| Authors: | CHEN DongLu LIN JianMin NI SiDao ZHU XiangYu ZHENG Hong |
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| Institution: | 1. School of Marine Science and Technology, Zhejiang Ocean University, Zhoushan Zhejiang 316022, China;2. State Key Laboratory of Geodesy and Earth's Dynamics, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan 430077, China;3. Ningbo Marine and Fisheries Information Monitoring Centre, Ningbo Zhejiang 315141, China |
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| Abstract: | Characteristics of seismic noise and spatial distribution of its sources have become the key issue for the further development of ambient noise tomography method. Seismic noise on ocean islands has its special features for being geographically isolated. Microseisms (~0.003-1 Hz) are the most energetic component of seismic noise, and their generation has been thought to be related with the interaction between ocean waves and the solid Earth. However, the relationship between microseisms on ocean islands and ocean wave field has not yet been fully investigated. This study investigates the temporal frequency characteristics of microseisms on ocean islands and its correlations with ocean wave field through interdisciplinary study between seismology and oceanography, using seismic wave records from island seismic stations in the Western North Pacific, continuous observation from moored ocean wave buoy, and numerical modeling by WAVEWATCH-Ⅲ ocean wave model. We find that microseisms on ocean islands are much stronger than in inland regions, and have distinct and steady seasonal variations. Microseisms in the frequency band of 0.12~0.32 Hz become weaker in seasons of summer and autumn (from May to October), while they become stronger in the seasons of winter and spring (from November to next April), which is consistent with the seasonal variation of oceanographic activities in the Northern hemisphere. In addition, the microseisms on ocean islands are found to be highly correlated with the ocean wave energy over the adjacent sea and significant ocean wave height from both observation and numerical modeling, which shows that the microseisms are mainly affected by adjacent ocean wave field. This study result also proves the possibility of seismological inversion of ocean wave field using microseismic signals, providing potentially a new supplementary approach of ocean wave observation to the marine science community. |
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| Keywords: | Ocean island Seismic noise Microseisms Temporal frequency characteristics Ocean wave Typhoon |
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