云南地区地脉动噪声特征分析研究

地震 ›› 2011, Vol. 31 ›› Issue (4): 58-67.

云南地区地脉动噪声特征分析研究

王伟涛¹, 倪四道², 王宝善¹

1.中国地震局地球物理研究所, 北京 100081;
2.中国科学院测量与地球物理研究所大地测量学重点实验室, 湖北武汉 430077

收稿日期:2011-03-22 修回日期:2011-07-04 出版日期:2011-10-31 发布日期:2021-09-09
作者简介:王伟涛(1979-), 男, 河北唐山人, 博士, 主要从事重复震源等研究。
基金资助:
中国地震局地球物理研究所基本科研专项(DQJB11C05, DQJB10B20, DQJB10A01)和国家自然科学基金(41004019, 40874095)共同资助

Study on the Characteristics of Microseisms in the Yunan Region, China

WANG Wei-Tao¹, NI Si-Dao², WANG Bao-Shan¹

1. Institute of Geophysics, C EA, Beijing 100081, China;
2. Key Laboratory of Dynamic Geodesy, Institute of Geodesy and Geophysics, CAS, Wuhan Hubei, 430077, China

Received:2011-03-22 Revised:2011-07-04 Online:2011-10-31 Published:2021-09-09

摘要/Abstract

摘要： 对地震台站记录到的长时间背景噪声进行互相关可以得到台站间的格林函数, 进而可以对地下介质波速结构和波速变化进行研究。对背景噪声来源方向和时空演化规律的分析, 是提高结果可靠性的重要基础。本文利用分布在云南境内的43个宽频带固定台站2008—2010年的垂直分量记录, 计算了两两台站之间的互相关函数, 并用平均能量流的方法研究了云南地区5~10 s以及10~20 s两个频段内地脉动噪声能量的空间分布和时间演化。研究结果表明, 云南地区5~10 s的地脉动噪声能量优势方向存在明显的季节性变化, 夏季优势能量方位角为180°~210°, 冬季则为70°~100°。而10~20 s的地脉动噪声优势方向方位角较为稳定, 为180°~210°。在这两个频段内噪声能量的强度都表现出了较强的季节性变化。同时发现在5~10 s频段瑞利面波之前存在视速度接近30 km/s的前驱信号, 并对其可能来源进行了分析。

关键词: 地脉动, 噪声源, 格林函数, 云南地区

Abstract: The Green's function between two stations can be extracted by cross correlating long time range ambient noise recorded by these stations, thus can be used for subsurface velocity inversion as well as time lapse monitoring of velocity variation. The knowledge of the variation of ambient noise direction and strength is important to improve the precision of these researches. Using the vertical component records from the Yunnan regional broadband seismic stations from 2008 to 2010, we calculated the noise cross correlation functions between each stations, then used the normalized background energy flux measurement to study the characteristicss of ambient noise in Yunan region, especially for secondary microseism period in 5~10s and primary microseism in 10~20 s. A significant direction variation of 5~10 s noise energy is observed, whose azimuth is 180°~210° in the Summer and moves to 70°~100° in the Winter. The direction of 10~20 s ambient noise is more stable covering 180°~210°. The strength of ambient noise of both types shows seasonal variation. We also observed strong near-zero arrivals with apparent velocity about 30 km/s, the possible mechanics of this precursors are discussed.

Key words: Microseisms, Cross correlation, Ambient noise source, Green's function

中图分类号:

P315

王伟涛, 倪四道, 王宝善. 云南地区地脉动噪声特征分析研究[J]. 地震, 2011, 31(4): 58-67.

WANG Wei-Tao, NI Si-Dao, WANG Bao-Shan. Study on the Characteristics of Microseisms in the Yunan Region, China[J]. EARTHQUAKE, 2011, 31(4): 58-67.

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