四川及邻区Lg尾波的Q值分布特征  

Distribution Characteristics of the Value Q of Lg Coda in Sichuan and its Adjacent Regions

作　　者：毛燕[1] 徐彦[1] 王彬[2] 胡家富[1] 丛连理[1] 

机构地区：[1]云南大学地球物理系,昆明650091 [2]云南省地震局,昆明650041

出　　处：《地震研究》2005年第1期38-42,共5页Journal of Seismological Research

基　　金：国家自然科学基金(49974012和40274030);云南省自然科学基金(99D0013M)联合资助.

摘　　要：首先利用叠加谱比法,对成都数字地震台网的12个台站及中国数字地震台网的5个台站所记录的504个宽带垂直分量进行分析,得到与各路径相对应的椭圆内的Lg尾波Q0和η的测量值,再应用反投影技术反演得出四川及邻区Lg尾波Q0和η的分布图像。结果表明Q0值的分布与构造活动性紧密相关,在所研究的范围内,Q0值在225～400的范围内变化。低的Q0值(225～250)发生在安宁河断裂、龙门山断裂和鲜水河断裂的交汇区域,以及由安宁河断裂和则木河断裂等多条断裂所组成的南北向断裂带;在川东的四川盆地,Q0值有所升高,在250～300的范围内变化;在所研究区域东南部的扬子地台,Q0值呈现出350～400的较高值。η值在04～08的范围内变化。绝大部分地区的η和Q0反向相关。We use the stack spectral ratio method to analyze 504 broad-band vertical components recorded by 12 stations in Chengdu Digital Seismological Network and 5 stations of China Digital Seismological Network, and obtain the measuring values of Q_0 and η of Lg coda in the ellipses corresponding to each path. Then we employ back-projection technique to invert and obtain the distribution images of Q_0 and η of Lg coda in Sichuan and its adjacent regions. The results indicate the distribution of Q_0 correlates with the tectonic activity closely. Q_0 varies between 225 and 400 in the studied area. There exists a low Q_0-value in the junction of the Anninghe fault, Longmenshan fault, and Xianshuihe fault, and the north-southern fault band consisting of various faults, including the Anninghe fault and Zemuhe fault. Q_0 increases slightly in the Sichuan basin of the eastern Sichuan, about 250～300. Q_0 exhibits higher values (350～400) in the Yangtse platform in the southeastern portion of the studied area.η varies in the range of 0.4～0.8. In the most part of the area,η correlates with Q_0 inversely.

关 键 词：LG尾波 Q值 叠加谱比法 反投影技术 四川及邻区 

分 类 号：P315.3[天文地球—地震学]