example_gazdag.m

著名的seismiclab的代码 是地震学研究人员必备的工具

%
%  example_gazdag.m
%
%  Gazdag Migration. Postack Depth Migration in v=v0 (Contant velocity)
%
%  SeismicLab
%  Version 1
%
%  written by M.D.Sacchi, last modified Sept., 2001  
%  [e-mail]
%
%  Copyright (C) 1998 Seismic Processing and Imaging Group
%

  clf;
% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% Prepare data (a band-limited impulse in x-t) 

  f0 = 35;         %  Central freq. of the Ricker wavelet
  dt = 4./1000;
  nx = 128;
  nz = 128;
  dz = 5;          % meters
  dx = 5;
  v  = 1700;       % velocity 
  nt = 64;         % time samples
  fmax = 2*f0;     % Must be less than Nyquist (fmax < 1/2/dt)

 [D] = spike(nt,nx,f0,dt);

% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% This is needed for forward modeling and migration

[Sfor, Smig, ARG] = propagator(v,nx,nz,nt,dx,dz,dt);

% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

con = 0; % This means do migration;

[Imp] = gazdag(D,v,nx,nz,nt,dx,dz,dt,fmax,con,Smig,ARG);

% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% Take the impulse respose back to x-t by
% forward modeling

con = 1; % this means modeling

[Dnew] = gazdag(Imp,v,nx,nz,nt,dx,dz,dt,fmax,con,Sfor,ARG);

% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% Display

figure(1); clf

subplot(221); imagesc(D);    title('Input in x-t') 
subplot(222); imagesc(Imp);  title('Impulse Response in x-z');
subplot(223); imagesc(Dnew); title('Impulse Response after forward modeling');