利用S波高频衰减对天山中东段地区地壳Q值成像  

Tomograpgy for Q of eastern section of the Tianshan area from highfrequency attenuation of S waves

作　　者：李金[1] 周龙泉[2] 王慧琳[3] 向元[1] 

机构地区：[1]新疆维吾尔自治区地震局 [2]中国地震台网中心,北京100045 [3]海南省地震局,海口570203

出　　处：《中国地震》2017年第2期229-238,共10页Earthquake Research in China

基　　金：地震科技星火计划(XH17041Y);2017年度震情跟踪合同制定向工作任务(2017010104);新疆地震局基金(201401)联合资助

摘　　要：利用天山中东段地区25个数字地震台站记录到的2009~2014年底5076个近震波形资料以及新疆地震台网提供的观测报告,采用遗传算法对S波位移谱的高频衰减进行拟合,得到19140条衰减算子t~*数据。根据这些t*数据,反演得到该区地壳Q_s值分布。结果表明,天山中东段地区平均Q_0值为520,其Q_s值分布及其所揭示的衰减变化特征与研究区的地表构造明显相关。天山南北两侧的山区盆地交汇部位Q_s值较低,而高Q_s值较为集中地分布于天山造山带内部。1900年以来天山中东段地区6级以上强震大多位于低Q_s值区域,该区24个高热流点也大多位于上述天山南北两侧的低Q_s值区域,热流值与衰减值呈负相关;此外,研究区的速度结构与衰减结构也呈一定的正相关,反映了二维衰减结构特征与速度结构、二维密度结构的一致性。Based on the waveform data of 5076 local earthquakes recorded at 25 stations of Xinjiang during the period of 2009- 2014 and the observation reports provided by the Xinjiang Digital Seismic Network,a data set of 19140 attenuation factor t＊ is obtained by fitting the high- frequency attenuation of S wave spectra with genetic algorithm. The spatial distribution of Qs is determined by inverting the data of t＊ with seismic tomography. The results show that the average Q0 in the eastern Tianshan is 520, there is a significant correlation between Qs value distribution or attenuation characteristics it disclosed and the surface structure of the study area. Qs value is lower in the intersection area of mountain basin which locates north and south sides of the Tianshan Mountains,and the high Qs distribution concentrates more inside the Tianshan orogenic belt. The M≥6.0 earthquakes are basically located in low-Qs region since 1900.24 high heat flow points in eastern Tianshan locate in north and south sides of Tianshan Mountains where low-Qs ,indicates a negative correlation. In addition,there is a positive correlation between the velocity structure and the attenuation structure in the study area, reflecting the consistency of a 2-D structure of the attenuation, velocity and the structure of the two-dimensional density.

关 键 词：天山中东段地区 S波高频衰减 衰减算子t＊ Q值成像 

分 类 号：P315[天文地球—地震学]