利用随机噪声研究华南地区瑞利波相速度特征  

Ambient Noise Rayleigh Wave Tomography across South China

作　　者：周旻炜 周龙泉[2] Zhou Minwei;Zhou Longquan(Institute of Earthquake Forecasting, China Earthquake Administration, Beijing 100036, China;China Earthquake Networks Center, Beijing 100045, China)

机构地区：[1]中国地震局地震预测研究所,北京市海淀区复兴路63号100036 [2]中国地震台网中心

出　　处：《中国地震》2018年第2期328-336,共9页Earthquake Research in China

基　　金：川滇国家地震监测预报实验场项目(2016CESE0101)资助

摘　　要：基于2009~2010年国家、区域测震台网的387个宽频带台站数据,通过互相关方法提取到可靠的瑞利波经验格林函数,利用相位匹配滤波时频分析技术测量瑞利波相速度频散曲线,最后采用噪声层析成像方法获得了华南地区不同周期的瑞利波相速度分布图。结果显示,华南地区速度结构横向变化幅度较小,反映了华南地区作为一个整体较为稳定,与华南地区自晚中生代以来未发生过强烈构造活动的特征基本一致;虽然华南地区整个岩石圈速度结构较为均匀,但扬子块体西部、四川盆地与扬子块体东部、华夏块体间存在明显的速度差异,体现在周期为8~10s时华夏块体相速度大于扬子块体西部、川滇块体以及四川盆地,由于沉积层较厚四川盆地速度最低;周期为10~30s时华夏块体面波相速度大于扬子块体西部和四川盆地,而川滇块体速度最低;周期为35s时扬子块体、华夏块体、四川盆地的速度基本一致,且高于川滇块体,这与华南地区地壳厚度明显小于川滇块体的特征相符。The data used in this study are continuous seismic waveforms recorded at broadband seismic stations including the 387 stations of China National and Regional Seismic Network in 2009 and 2010. Cross-correlations are computed in daily segment to retrieve the reliably empirical Rayleigh wave Green ＇s function. Rayleigh wave phase velocity dispersion curves are measured using a phase-matched filter and frequency time analysis technique. We apply seismic ambient noise tomography to image the different period phase velocity maps of South China. Our results indicate that the phase velocity of the whole lithosphere in South China is relatively uniform,which also reflects that South China as a whole is characterized of the relative stability. Our results agree that there have been no intense tectonic activities in South China since late Mesozoic. Although the velocity structure of the whole lithosphere in South China is relatively uniform,distinct velocity differences appear in the west of the Yangtze Block,Sichuan Basin,the east of Yangtze Block and Cathaysia Block,namely,the 8-10 s period phase velocity of Cathaysia Block is higher than the west of the Yangtze Block,Sichuan-Yunnan region and Sichuan Basin. The Sichuan Basin has the lowest velocity because of the relatively thick sedimentary layer. The velocity of the Cathaysia Block in the 10-30 s period phase is higher than those of the Yangtze Block and Sichuan Basin and the Sichuan-Yunnan region has the lowest velocity. In the 35 s period phase,the velocities of the Yangtze Block and Cathaysia Block and Sichuan Basin are basically the same and higher than that of the Sichuan-Yunnan region. This is consistent with the feature that the crustal thickness in South China is obviously smaller than that of the Sichuan-Yunnan region.

关 键 词：随机噪声 瑞利波层析成像 华夏块体 扬子块体 

分 类 号：P315[天文地球—地震学]