文档介绍：
Rayleigh 面波衰减特性与汶川地震关系研
究#
程先琼*
5
10
15
(成都理工大学地球物理学院,成都 610059)
摘要:搜集中国大陆 72 个数字地震台站 7321 个长周期波形记录,从中挑选出符合条件的
489 对经过中录,采用相匹配滤波和频率域维纳滤波相结合的方法,计
算出双台之间的混合路径衰减系数,再通过网格化反演得到中国大陆每个网格单元的纯路径
衰减系数。结果显示:短周期(深度约 20~50km)四川盆地 Rayleigh 面波衰减较小,松潘
甘孜地块 Rayleigh 面波衰减较大,反映在该深度四川盆地已进入上地幔,松潘甘孜地块仍
处于下地壳;地震波衰减特性与强震分布关系密切,汶川地震及余震平面分布在四川盆地低
衰减区与青藏高原东缘高衰减区的过渡地带,并且有着略偏向低衰减一侧的趋势。汶川地震
序列纵向主要发生在壳内高衰减区上方的上地壳深度范围内;松潘—甘孜地块内,存在壳内
的由西向东逐渐减薄的楔状高衰减区,该高衰减区在下地壳延伸到扬子地块之下。不存在四
川盆地向龙门山以西的俯冲现象,松潘—甘孜地块的上地壳与上地壳内高衰减区滑脱解耦,
形成铲形逆冲推覆,是形成汶川地震的主要构造原因。
关键词:固体地球物理学;Rayleigh 面波;衰减系数;龙门山;汶川地震;双台法
中图分类号:
20
The Relation between Distribution of Attenuation for
Rayleigh Surface Wave and Reason of Wenchuan
Earthquake
CHENG Xianqiong
25
30
35
(Geophyics School, Chengdu University of Technology, Chengdu 610059)
Abstract: We selected 489 pairs of Rayleigh wave from 7321 wavefoms recorded by 72 stations in
continental China. The pure-path attenuation coefficients of the Rayleigh wave for each cell in China
are attained by inversting each cell after getting mix-path attenuation coefficients by the phase-matched
method and the frequency-domain Wiener filter was conclude that the attenuation of
Rayleigh wave is lower in Sichuan basin than Songpan-Ganmzi fold belt at short period,that is
20~50km,which shows this depth is upper mantle in east china and crust in west china; Also