Resolution Limits of Traveltime Tomograms based on Diffraction Physics

Friday, April 26, 2002 - 9:30am - 10:15am
Keller 3-180
Gerard Schuster (The University of Utah)
Uncertainty estimates typically assume that the correct physics is used to predict the data, thereby ignoring uncertainty due to incorrect physics. This can be a major problem for inversion algorithms, particularly traveltime tomography. Ray-based traveltime tomography assumes a high-frequency approximation to the wave equation, yet many types of seismic measurements violate this approximation. Consequently, the uncertainty estimates of traveltime tomograms based strictly on statistical arguments are significantly flawed. To account for uncertainty based on diffraction physics, we apply the Generalized Radon Transform to the Rytov equation and show how to construct traveltime wavepaths that connect each source-receiver pair. The intersection of these wavepaths define the spatial limits of resolution about a scattering point. I illustrate how to use these wavepaths for several traveltime tomography examples, including surface-based refraction tomography and crosswell tomography.