par Charléty, J.;Voronin, S.;Nolet, G.;Loris, Ignace ;Simons, Frederik;Sigloch, Karin;Daubechies, Ingrid
Référence Journal of Geophysical Research (Solid Earth), 118, page (4887-4899)
Publication Publié, 2013
Référence Journal of Geophysical Research (Solid Earth), 118, page (4887-4899)
Publication Publié, 2013
Article révisé par les pairs
Résumé : | We present a realistic application of an inversion scheme for global seismic tomography that uses as prior information the sparsity of a solution, defined as having few nonzero coefficients under the action of a linear transformation. In this paper, the sparsifying transform is a wavelet transform. We use an accelerated iterative soft-thresholding algorithm for a regularization strategy, which produces sparse models in the wavelet domain. The approach and scheme we present may be of use for preserving sharp edges in a tomographic reconstruction and minimizing the number of features in the solution warranted by the data. The method is tested on a data set of time delays for finite-frequency tomography using the USArray network, the first application in global seismic tomography to real data. The approach presented should also be suitable for other imaging problems. From a comparison with a more traditional inversion using damping and smoothing constraints, we show that (1) we generally retrieve similar features, (2) fewer nonzero coefficients under a properly chosen representation (such as wavelets) are needed to explain the data at the same level of root-mean-square misfit, (3) the model is sparse or compressible in the wavelet domain, and (4) we do not need to construct a heterogeneous mesh to capture the available resolution. |