相空间波前构造法地震多值射线追踪的改进
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摘要
当存在低速异常体或弯曲界面时,地震波前出现的自相缠绕(或地震多值)现象是地震波在介质中传播的自然现象,但在以往的研究中时常被忽略。而这些后续波有可能携带低速区或不规则反射界面的有用信息,可以弥补射线覆盖不足等问题。本文在相空间方法的基础上,对波前构造法进行了改进,其中包括反射界面处理过程中采用连续波前映射法和射线追踪过程中采用检波器精确定位算法等。几种简单模型的数值模拟结果表明,改进后的波前构造法是一种计算地震多值射线路径行之有效的算法。
Seismic wavefront self-interaction or multivalued seismic ray is a natural phenomenon when the seismic wave propagates through a media containing low-velocity abnormal bodies or bending interfaces,which is commonly ignored in previous study.However,it is true that the later arrivals may contain some useful information regarding to the low velocity zone or the irregular reflection interface and have a potential to improve the ray coverage.Based on the phase space method,we improve in this paper the wavefront construction method in two aspects:firstly,using a continuous wavefront mapping method to deal with the reflection interface;secondly,using aprecise receiverlocation algorithm in the ray tracing process.Several simple model simulations indicate that the improved wavefront construction method in phase space is an effective and accurate approach to trace multi-valued seismic rays.
Seismic wavefront self-interaction or multivalued seismic ray is a natural phenomenon when the seismic wave propagates through a media containing low-velocity abnormal bodies or bending interfaces,which is commonly ignored in previous study.However,it is true that the later arrivals may contain some useful information regarding to the low velocity zone or the irregular reflection interface and have a potential to improve the ray coverage.Based on the phase space method,we improve in this paper the wavefront construction method in two aspects:firstly,using a continuous wavefront mapping method to deal with the reflection interface;secondly,using aprecise receiverlocation algorithm in the ray tracing process.Several simple model simulations indicate that the improved wavefront construction method in phase space is an effective and accurate approach to trace multi-valued seismic rays.
引文
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[11]韩复兴,孙建国,杨昊.基于二维三次卷积的波前构建射线追踪.吉林大学报(地球科学版),2008,38(2):336～340Han Fuxing,Sun Jianguo,Yang Hao.Ray tracing ofwavefront construction by bicubic convolution inter-polation.J Jilin University(Earth Science Edition),2008,38(2):336～340
[12]Carl de Boor.A Practical Guide to Splines.Spring-er,2001,87～106
[13]Rawlinson N,Sambridge M.Multiple reflection andtransmission phases in complex layered media using amultistage fast marching method.Geophysics,2004,69(5):1338～1350
[14]王润科,张彦丽.判断点与多边形位置关系的算法综述.甘肃联合大学学报,2006,20(6):32～41Wang Runke and Zhang Yanli.The summarize of al-gorithm for judgment of relations between polygonsand points.J Gansu Lianhe University,2006,20(6):32～41
[2]Rawlinson N,Sambridge M and Hauser J.Multipath-ing,reciprocal traveltime fields and raylets.GeophysJ Int,2010,181(2):1077～1092
[3]唐小平,白超英,刘宽厚.分区多步最短路径极值法多值多次反射波追踪.地球物理学进展,2011,26(6):2064～2074Tang Xiaoping,Bai Chaoying,Liu Kuanhou.Multi-valued and multiple reflected raytracing with an ex-treme value based on the multistage modified shor-test-path method.Progress in Geophysics,2011,26(6):2064～2074
[4]Vinje V,Iversen E and Gjystdal H.Traveltime andamplitude estimation using wavefront construction.Geophysics,1993,58(8):1157～1166
[5]Vinje V,Iversen E,Astebl K and Gjystdal H.Es-timation of multivalued arrivals in 3D models usingwavefront construction-Part I.Geophys Prospect,1996,44(5):819～842
[6]Vinje V,Astebol K,Iversen E and Gjystdal H.3-Dray modelling by wavefront construction in open mod-els.Geophys Prospect,1999,64(6):1912～1919
[7]Lambar′e G,Lucio P S and Hanyga A.Two-dimen-sional multivalued traveltime and amplitude maps byuniform sampling of a ray field.Geophys J Int,1996,125(2):584～598
[8]Steinhoff J,Fan M and Wang L.A new Eulerianmethod for the computation of propagating short a-coustic and electromagnetic pulses.J Comp Phys,2000,157(2):683～706
[9]清华大学、北京大学《计算数学》编写组.计算方法(上册).北京:科学出版社,1974,215～221
[10]韩复兴,孙建国,杨昊.不同插值算法在波前构建射线追踪中的应用与对比.计算物理,2008,25(2):197～202Han Fuxing,Sun Jianguo,Yang Hao.Interpolationalgorithms in wavefront construction.Chinese J Com-put Physics,2008,25(2):197～202
[11]韩复兴,孙建国,杨昊.基于二维三次卷积的波前构建射线追踪.吉林大学报(地球科学版),2008,38(2):336～340Han Fuxing,Sun Jianguo,Yang Hao.Ray tracing ofwavefront construction by bicubic convolution inter-polation.J Jilin University(Earth Science Edition),2008,38(2):336～340
[12]Carl de Boor.A Practical Guide to Splines.Spring-er,2001,87～106
[13]Rawlinson N,Sambridge M.Multiple reflection andtransmission phases in complex layered media using amultistage fast marching method.Geophysics,2004,69(5):1338～1350
[14]王润科,张彦丽.判断点与多边形位置关系的算法综述.甘肃联合大学学报,2006,20(6):32～41Wang Runke and Zhang Yanli.The summarize of al-gorithm for judgment of relations between polygonsand points.J Gansu Lianhe University,2006,20(6):32～41
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