Accession Number : ADA438856


Title :   Synthesizing High-Frequency (1-25 HZ) Regional Phases at Large Distances (>1000 KM) Using Generalized Screen Propagators (GSP)


Descriptive Note : Technical rept. 1 May 1997-30 Apr 2000


Corporate Author : CALIFORNIA UNIV SANTA CRUZ CA INSTITUTE OF GEOPHYSICS AND PLANETARY PHYSICS


Personal Author(s) : Wu, Ru-Shan ; Xie, Xiao-Bi ; Wu, Xianyun


Full Text : http://www.dtic.mil/get-tr-doc/pdf?AD=ADA438856


Report Date : SEP 2004


Pagination or Media Count : 53


Abstract : Based on the half-space screen propagator developed in our previous project, we successfully extended the method to the case of irregular surface topography by the conformal and non-conformal topographic transforms. Its validity and potential applications have been numerically demonstrated by comparing with the boundary element method. The new method can handle combined effects of small-scale heterogeneities (random media) and rough random topography on Lg wave propagation. It is also 2-3 orders of magnitude faster than the finite difference method. In the P-SV wave case, reflected plane waves from a free surface are incorporated into the elastic screen method for Lg wave simulation. Due to the presence of a surface wave (Rayleigh wave), both the real and imaginary pans of the wavenumber must be included. Body waves including reflected and convened waves are calculated using real wavenumber integration; surface wave are calculated with imaginary wavenumber integration. The comparison between results from numerical test and the wavenumber integration method shows excellent agreement. Numerical results show that this is a promising method for simulating path effects in different regions for various monitoring discriminants such as Pn/L or Sn/Lg, etc.


Descriptors :   *WAVE PROPAGATION , HIGH FREQUENCY , SURFACE WAVES , LONG RANGE(DISTANCE) , PLANE WAVES , BOUNDARY ELEMENT METHODS , RAYLEIGH WAVES , SEISMIC WAVES , NUMERICAL ANALYSIS , FINITE DIFFERENCE THEORY.


Subject Categories : NUMERICAL MATHEMATICS
      THEORETICAL MATHEMATICS
      OPTICS


Distribution Statement : APPROVED FOR PUBLIC RELEASE