| 大西洋中北部双频微地动特征 |
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| 引用本文： | 方益志,薛梅.大西洋中北部双频微地动特征[J].地震学报,2021,43(2):204-214. |
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| 作者姓名： | 方益志 薛梅 |
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| 作者单位： | 中国上海 200092 同济大学海洋与地球科学学院 |
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| 基金项目： | 国家自然科学基金面上项目（42076064）和上海佘山地球物理国家野外科学观测研究站开放基金（2020K03）共同资助 |
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| 摘 要： | 本文对大西洋中北部两侧五个地震台站2015年记录到的地震数据进行处理，计算噪声功率谱密度和概率密度函数，并通过极化分析对双频微地动不同周期的主导源区方位角分布进行了分析。研究结果显示:大西洋中北部台站双频微地动发生显著分裂，各台站的峰值周期各不同，且来自相同方向和不同方向的双频微地动都有可能产生双频微地动分裂；大西洋中北部的噪声功率谱密度随季节变化复杂，部分台站冬季的功率谱密度振幅比夏季强，部分台站夏季的比冬季强；而大西洋中北部台站源区方位受季节影响不大，台站主要源区的方位不变，且两季的源区方位角在大范围内重合；大西洋东岸中北部台站，夏季受台站以南大西洋源区影响更多，冬季受台站以北大西洋源区影响更多；靠近加勒比海位于大西洋西岸的台站，其双频微地动源区方向在冬季和夏季都更多地指向加勒比海；大西洋西岸纬度最低的台站MPG，其双频微地动在冬季主要受台站以北大西洋源区的影响，而在夏季则同时受到台站以北大西洋源区和台站西南方位很可能源于太平洋源区的共同影响。
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| 关 键 词： | 双频微地动 大西洋中北部 功率谱密度 概率密度函数 极化分析 |
| 收稿时间： | 2020-06-23 |
Characteristics of double-frequency microseisms in the central and northern Atlantic Ocean |
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| Fang Yizhi,Xue Mei.Characteristics of double-frequency microseisms in the central and northern Atlantic Ocean[J].Acta Seismologica Sinica,2021,43(2):204-214. |
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| Authors: | Fang Yizhi Xue Mei |
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| Affiliation: | School of Ocean and Earth Science，Tongji University，Shanghai 200092，China |
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| Abstract: | The splittings of double-frequency microseisms have been observed from the published spectra of microseisms at the seismic stations on both sides of the Atlantic Ocean. However, the splitting mechanism has not been investigated yet. In this paper, the seismic data of the year 2015 recorded by five seismic stations located on both sides of the central and northern Atlantic Ocean are processed. We calculate power spectral density of the ambient noise and obtain corresponding probability density function. And we also perform polarization analysis to study the distribution of azimuth of main source regions at the periods of double-frequency microseisms.The results show that significant splittings of the double-frequency microseisms are observed at the five stations located on both sides of the central and northern Atlantic Ocean, the peak periods observed at each station were different and the source regions from the same direction and different directions are both capable of generating the splitting of double-frequency microseisms. The power spectral density （PSD） of microseisms in the central and northern Atlantic Ocean varies with seasons. Some stations have stronger PSD amplitudes in winter than in summer, and the others have stronger amplitudes in summer than in winter. The main source region directions of the central and northern Atlantic stations are not affected by seasons. Therefore the main source region directions remains almost the same in winter and summer, and the source region directions of the two seasons overlap in a wide range. For the stations located on the east coast of the central and north Atlantic Ocean, the main sources of the double frequency microseisms are more from the Atlantic Ocean to the south of the stations in summer, and more from the Atlantic Ocean to the north of the stations in winter. For the stations nearby the Caribbean Sea on the west coast of the Atlantic Ocean, the source directions of the double-frequency microseisms mostly point to the Caribbean Sea in both winter and summer. For the station MPG located at the lowest latitude in this study, the double-frequency microseisms mainly come from the Atlantic Ocean to the north of the stations in winter, while it has additional sources from the southwest directions in summer, probably from the Pacific Ocean. |
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