Tomographic errors from wave front healing: more than just a fast bias

Malcolm, Alison and Trampert, Jeannot (2011) Tomographic errors from wave front healing: more than just a fast bias. Geophysical Journal International, 185 (1). pp. 385-402. ISSN 0956-540X

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Abstract

Wave front healing, in which diffractions interfere with directly travelling waves causing a reduction in recorded traveltime delays, has been postulated to cause a bias towards faster estimated earth models. This paper reviews the theory from the mathematical physics community that explains the properties of diffractions and applies it to a suite of increasingly complicated numerical examples. We focus in particular on the elastic case and on the differences between P and S healing. We find that rather than introducing a systemic fast bias, wave front healing gives a more complicated bias in the results of traveltime tomography, with fast anomalies even manifesting themselves as slow anomalies in some situations. Of particular interest, we find that a negative correlation between the bulk and shear or compressional velocities may result to a large extend from healing.

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