青藏高原东北缘背景噪声特征分析  

Characteristic of Ambient Seismic Noise of the Northeastern Margin of Tibetan Plateau

作　　者：马小军[1,2] 马禾青[2] 李军[3] 许晓庆[2] 曾宪伟[2] 罗国富[2] 

机构地区：[1]中国地震局兰州地震研究所,甘肃兰州73000 [2]宁夏回族自治区地震局,宁夏银川750001 [3]福建省地震局,福建福州350001

出　　处：《地震研究》2014年第4期607-613,669,共7页Journal of Seismological Research

基　　金："十二五"国家科技支撑计划项目(专题七2012BAK19B01-07);地震科技星火计划项目(XH14051YSX;XH13024Y)联合资助

摘　　要：采用2009年青藏高原东北缘55个数字化宽频带地震台站的垂直分量波形数据,计算了台站间噪声互相关函数,得到了Rayleigh经验格林函数。利用信噪比和归一化平均能量流的方法分析了青藏高原东北缘背景噪声源的方位分布和季节性变化特征。结果表明,5-10 s周期噪声源方位分布上较为稳定,不随季节变化,噪声源能量集中在105°-165°方向上,噪声源主要来自于太平洋。10-20 s周期噪声源季节性变化特征明显,夏季的噪声能量主要集中在165°-210°方向上,噪声源来自于印度洋海洋活动;冬季主要集中在300°-350°和165°-210°方向上,噪声能量主要来源于太平洋和北大西洋。Basing on the vertical component waveforms recorded by 55 digital broadband seisimic stations located at the northeastern margin of the Tibetan Plateau, we calculate the cross-correlation Green functions of ambient seismic noise between two stations, and obtain the Rayleigh wave empirical Green＇s function. The techniques of signal- to-noise ratios （SNR） and normalized average energy flux of Rayleigh wave are applied to analyze the azimuthal distribution and seasonal variability of ambient noise sources in the northeastern margin of the Tibetan Plateau. In the period of 5 - 10 s, the azimuthal distribution of noise source is stable, and don＇t change with the season. The energy of noise source focuses on the azimuth of 105°- 165°, which is mainly affected by Pacific Ocean. In the period of 10 - 20 s, the azimuthal of noise source varies seasonally, and the energy of noise source focuses on the azimuth of 165°-210° in summer and moves to the azimuth of 300° -350° and 165° -210° in winter, which suggests that the noise source may be affected by the Indian Ocean in summer, the Pacific and North Pacific Oceans in winter.

关 键 词：青藏高原东北缘 噪声源 经验格林函数 信噪比 归一化平均能量流 

分 类 号：P315.3[天文地球—地震学]