Results of the homogeneous inversion for the P and SV waves show a considerable degree of elliptical anisotropy. Even with the absence of SH information we were able to obtain four of the five transverse isotropic elastic parameters. Although the insufficient coverage of this specific dataset compromises the uniqueness of the solution, the first iterations of the layered scheme represent at least one resolution-step ahead of the homogeneous results. Claerbout J. F. A test of linear inversion theory yields weak and unconvincing extrapolations of a CMP gather. We have recently begun looking at an interesting dataset where ambient seismic noise was recorded using a 480 channel array of buried geophones in a producing field.
Pumps provide strong, broadband coherent energy.
Using techniques that we have applied to other ambient noise datasets, we hope to locate sources of noise on the surface and at depth, and infer some details about the subsurface. Ji J. A basic part of seismic migration is downward continuation of surface data into the subsurface. The Kirchhoff integral can only be used to propagate wavefields forward. Backward propagation is based on the Porter-Bojarski integral. Both integrals simplify if data is registered on a plane.