Traveltime Solutions vs. Wavefields : GP 160

This page examines acoustic wavefield and traveltime modeling as applied to a couple of simple (and one complex) velocity models. Each row in the table below provides links to a model, a traveltime map, and a wavefield movie (mpg) in addition to generic information on the simulation. Both traveltimes and wavefields were calculated on the same 2D grids, 100x100m and 800x800 grid points.

The traveltime maps were calculated using a finite-difference eikonal solver which combines the evaluation order used in Sethian's Fast Marching algorithm with the accurate 2nd order stencils used in Vidale's original FD eikonal method. Acoustic wavefields were calculated using a 2nd order (in space and time) FD method assuming constant density, very similar to a 2D version of the aco1dvvcd code supplied in the 1D Wave toolbox.

Model Dimensions

Simulation Test Runs/Comparisons

Model Eikonal Solution Movie (Acoustic) Model Characteristics Run Parameters
  • Layer 1: 1500 m/s
  • Layer 2: 4000 m/s
  • Interface at 50 m
  • Source Wavelet: 400 hz Ricker
  • DX = DZ = 0.125 m
  • Source Location: Grid (150,200)
  • Background: 1500 m/s
  • Diffractor: 4000 m/s
  • Source Wavelet: 400 hz Ricker
  • DX = DZ = 0.125 m
  • Source Location: Grid (250,600)
  • Background: 4000 m/s
  • Block: 1500 m/s
  • Source Wavelet: 400 hz Ricker
  • DX = DZ = 0.125 m
  • Source Location: Grid (100,400)
jfrank@pangea.stanford.edu