基于三分量数据的云南地区背景噪声源分析  

Analysis on Ambient Noise Origin in Yunnan Area Basedon Three-Component Data

作　　者：张演[1] 郑定昌[1] 林国良[1] 吕帅 ZHANG Yan;ZHENG Dingchang;LIN Guoliang;LYU Shuai(Yunnan Earthquake Agency,Kunming 650224,Yunnan,China)

机构地区：[1]云南省地震局,云南昆明650224

出　　处：《地震研究》2020年第4期689-700,768,共13页Journal of Seismological Research

基　　金：云南省地震局自立项目(2017ZX01,2018K06)联合资助.

摘　　要：背景噪声特性及噪声源的分布逐渐成为深化背景噪声互相关研究的关键问题。基于2015-2016年云南地区48个固定数字地震台的连续三分量记录,使用互相关计算提取台站对经验格林函数,基于经验格林函数正负支信噪比特性,结合海浪波高数据,得到云南地区5~10 s,10~20 s,20~40 s台站对信噪比的方位分布和时间变化特征。结果表明:云南地区三分量的噪声源优势方位在不同周期内均有差别,5~10 s噪声源优势方位变化较稳定,当海洋活动相对剧烈时,ZZ,RR分量比TT分量易受到影响;10~20 s噪声源优势方位变化与海洋活动的季节性变化规律较一致,1-6月ZZ,RR分量优势方位角指向E向和WS向,TT分量则以E向为主,7-12月ZZ,RR分量优势方位角明显指向WS向,TT分量在7-9月指向WS向,在10-12月则指向E向和WS向;20~40 s内的噪声强度较小且随时间变化稳定。因此,云南地区噪声能量源主要与北太平洋和孟加拉湾-安达曼海-北印度洋一带的活动有关。The characteristics of ambient noise and the distribution of the ambient noise origin have gradually become the key issues to deepen the research in the empirical Green s function.Based on the three-component continuous record of 48 seismic stations in Yunnan area from 2015 to 2016,we extracted the empirical Green s function of stations by using cross-correlation calculation.Based on the characteristics of the signal-to-noise(SNR)ratio of the positive and negative branches of the cross-correlation function,combined with the wave height data,we obtained the azimuthal distribution and time variation characteristics of SNR of stations between 5~10 s,10~20 s,20~40 s in Yunnan area.The results show that the principal azimuth of the ambient noise origin of three-component in Yunnan area are different in different periods.For the 5~10 s band,it is relatively stable.When the ocean activity is relatively intense,the ZZ and RR components are easier to be affected than the TT components.For the 10~20 s band,it is consistent with the seasonal variability of the ocean activities.The principal azimuths of ZZ and RR components points to E and WS direction from Jan.to Jun.,while that of TT component mainly points to E direction.The principal azimuths of ZZ and RR components point to WS from Jul.to Dec.,while that of TT component points to WS from Jul.to Dec.,E and WS direction from Oct.to Dec.For the 20~40 s band,the noise intensity is smaller and stable with time.Therefore,the ambient noise origin in Yunnan area is likely to be related to the activities of North Pacific Ocean and Bengal Bay-Andaman Sea-North Indian Ocean.

关 键 词：经验格林函数 互相关 信噪比 噪声源 海洋活动 

分 类 号：P315.6[天文地球—地震学]