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《地震研究》[ISSN:1000-0666/CN:53-1062/P]

卷:

期数:

2025年03期

页码:

413-421

栏目:

出版日期:

2025-04-15

文章信息/Info

Title:

Analysis of Characteristics of the Ambient Noise Source Using the NCF-based Beamforming

作者:

赵玲云¹; 庞卫东¹; 王伟涛²; 袁松湧²; 王芳²; 李丹宁¹

(1.云南省地震局,云南 昆明 650224; 2.中国地震局地球物理研究所,北京 100081)

Author(s):

ZHAO Lingyun¹; PANG Weidong¹; WANG Weitao²; YUAN Songyong²; WANG Fang²; LI Danning¹

(1.Yunnan Earthquake Agency,Kunming 650224,Yunnan,China)(2.Institute of Geophysics,China Earthquake Administration,Beijing 100081,China)

关键词:

背景噪声;  噪声源;  噪声互相关函数;  聚束分析

Keywords:

ambient noise;  noise source;  NCF;  beamforming

分类号:

P315.3

DOI:

10.20015/j.cnki.ISSN1000-0666.2025.0043

摘要:

基于密集台阵的背景噪声成像是目前研究地壳结构的重要技术手段,背景噪声的噪声源演化规律的分析可加深对噪声互相关中信号的认识。对密集台阵开展聚束分析可对其所记录到的噪声类型、来源方位和季节变化等做出分析。利用2013—2016年ChinArray二期台阵南部322个宽频带地震台的垂直分量数据,计算各台站对的噪声互相关函数(NCF),通过基于NCF的台阵聚束方法对4～30 s的噪声信号做慢度分析,得到了4～8、8～12、12～20、20～30 s 4个不同频段范围的聚束输出图像。结果表明:①在不同的周期频段,噪声信号成分并不相同:在周期较长的频段,信号主要为面波,在周期较短的频段,除了面波信号,还存在一定的体波信号; ②在聚束输出图像上可以直观地观察到不同频段信号成分的变化; ③在不同的周期频段,噪声信号的优势来源方向各不相同,且具有明显的季节变化,其中来源方向对应于北半球海域的噪声能量呈现出冬季较强、夏季较弱的特征,而对应于南半球海域的噪声能量变化趋势与之相反,与全球海洋活动相符。

Abstract:

Seismic ambient noise tomography based on dense seismic array is currently an important method for the investigation of the crustal structure.Analyzing the changes in ambient noise source plays an important role in improving our understanding of the signal of NCF.The NCF-based slowness beamforming technique can study the composition of microseisms,azimuthal anisotropy and seasonal variation.In this study,we calculate the NCF from 2013 to 2016 using the continuous vertical records of 322 broadband seismic stations which are evenly distributed in a square in southern part of the ChinArray Phase II.Using the NCF-based slowness beamforming technique,we carry out direct slowness analysis in the 4-30 s period and obtain the beamforming output in the period bands 4-8 s,8-12 s,12-20 s and 20-30 s respectively.The result shows that the components of ambient noise sources vary in different period bands.In higher-frequency bands the body wave is observed while in lower-frequency bands the body wave is weaker and surface wave signal becomes dominant.In different period bands dominant ambient noise comes from different directions,and varies along with the season.The ambient noise coming from the northern Hemisphere features stronger in Winter,and weaker in Summer.Meanwhile,the ambient noise coming from the southern Hemisphere features weaker in Winter,and stronger in Summer.This seasonality and frequency dependence of noise sources distribution is well correlated with variations of the ocean activity.

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备注/Memo

备注/Memo:

收稿日期:2024-08-21.
基金项目:云南省地震局青年地震科学基金(2023K04); 云南省地震工程勘察院有限公司“地震观测网建设”项目(k24-34); 云南省地震局“压缩感知与稀疏反演理论研究”创新团队项目(CXTD202407).
第一作者简介:赵玲云(1995-),工程师,主要从事地震背景噪声和噪声源研究.E-mail:18487202725@163.com.
通信作者简介:庞卫东(1983-),高级工程师,主要从事震害防御研究.E-mail:wdpang1983@qq.com.

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更新日期/Last Update: 2025-04-15