汶川地震前后波速比变化特征的再研究  

Restudy of the variation of v_P/v_S before and after the Wenchuan earthquake

作　　者：李艳娥[1] 王林瑛[1] 郑需要[1] 

机构地区：[1]中国地震局地球物理研究所,中国北京100081

出　　处：《地震学报》2014年第3期425-432,531,共8页Acta Seismologica Sinica

基　　金：国家自然科学基金(41090292);中国地震局地球物理研究所基本科研业务专项(DQJB12C06)联合资助

摘　　要：收集整理了四川省地震台网1990—2012年产出的地震直达波震相数据,利用单台多震和达法对2008年汶川MS8.0地震前后四川地区的波速比变化特征进行了分析研究(共筛选出13个数据量较为丰富、连续性较好的台站).结果显示:其中位于龙门山断裂中北段西侧的4个台站,震前出现长达7年左右的中长期波速比低值异常;其它9个台站的波速比震前变化基本稳定.震前波速比出现异常的4个台站的分布与汶川MS8.0地震孕震区范围大体一致,从而为研究汶川MS8.0地震前是否存在地壳介质特性的时间变化过程,提供了有力的判定依据.Based on the seismic phase data recorded by Sichuan Digital Network from 1990 to 2012,this paper analyzes the variation of wave velocity ratio VP/VS before and after the 2008 Wenchuan MS8.0 earthquake by using Wadati method of single station and multi-earthquake.We carefully winnow the date and select 13 stations with relatively abundant and continuous data.The results show that the wave velocity ratio obviously decreased at four stations before the Wenchuan earthquake in the western side of middle-northern Longmenshan fault,which lasts for almost seven years; while the ratio did not show abnormal varaiton at the other nine stations.The position of the four stations with anomalous wave velocity ratio are consistent with Wenchuan earthquake seismogenic zone,providing sufficient evidence for whether the temporal variation process of crustal media characteristics exists before the Wenchuan earthquake.

关 键 词：2008年汶川MS8 0地震 波速比 单台多震和达法 地壳介质特性 

分 类 号：P315.72[天文地球—地震学]