鄂尔多斯块体Lg尾波衰减及其分布图像  

Lg coda attenuation and its distribution image beneath Ordos massif

作　　者：刘红桂[1] 周红晖 陈书清[3] 金春华[4] 

机构地区：[1]中国地震局地球物理研究所,北京100081 [2]湖南新邵教师进修学校,新邵422900 [3]江苏省地震局,南京210014 [4]宁夏回族自治区地震局,银川750001

出　　处：《地球物理学进展》2008年第2期351-358,共8页Progress in Geophysics

基　　金：国家自然基金课题(40574016);十五国家重点科技攻关项目(2004BA601B01-04-03)资助

摘　　要：利用32个地震台站记录到的19次地震事件共487条垂直方向数字化波形记录,采用单台记录叠加频谱比法(SSR法)计算得到了每条地震记录在0.6～10Hz范围内共51个频率点的Lg尾波Q值,并统计得到了鄂尔多斯块体Lg尾波衰减的频率依赖关系.同时,利用遗传算法计算得到了鄂尔多斯块体Lg尾波在频率为1Hz处的衰减(Q0)值、频率依赖指数(η)值的空间分布,并计算了其误差的空间分布,讨论了成像分辨率.结果表明,鄂尔多斯块体虽然是一个稳定构造地区,但其Lg尾波Q0值低于加拿大地盾、西伯利亚地台的Q0值,其η值大于加拿大地盾、西伯利亚地台的结果,且其Q0值、η值具有横向不均匀性的特征.Q0值的空间分布与地震活动、地热流值分布具有较好的一致性.The quality factor of Lg coda wave beneath Ordos massif is evaluated by using the stacked spectral ratio method. The measurement is made from Lg wave records of 19 earthquakes at 32 vertical seismic stations of the Shanxi seismic network,Shaanxi seismic network and Ningxia seismic network. Q has been calculated for a set of 51 frequencies between 0.6Hz and 10Hz for each seismic record and has been found to be a relation between Q value and frequency. The images of the quality factor at 1.0Hz （Q0） and the frequency index （η） have been calculated, by using the genetic algorithm. Although they are all in stable regions, the Ordos show high attenuation moreover Canadian shield and Siberian platform show low attenuation. The tomographic patterns of Q0 correlate well with those of the level of seismic activity and the heat flow field in the Ordos massif.

关 键 词：鄂尔多斯块体 LG尾波 Q值 叠加频谱比法 遗传算法 

分 类 号：P315[天文地球—地震学]