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A hybrid approach to compute seismic travel times in three‐dimensional tetrahedral meshes.

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Nasr, Maher; Giroux, Bernard; Dupuis, Christian (2020). A hybrid approach to compute seismic travel times in three‐dimensional tetrahedral meshes. Geophysical Prospecting . DOI: 10.1111/1365-2478.12930.

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Résumé

We propose an optimized method to compute travel times for seismic inversion problems. It is a hybrid method combining several approaches to deal with travel time computation accuracy in unstructured meshes based on tetrahedral elementary cells. As in the linear travel time interpolation method, the proposed approach computes travel times using seismic ray paths. The method operates in two sequential steps: At a first stage, travel times are computed for all nodes of the mesh using a modified version of the shortest path method. The difference with the standard version is that additional secondary nodes (called tertiary nodes) are added temporarily around seismic sources in order to improve accuracy with a reasonable increase in computational cost. During the second step, the steepest travel time gradient method is used to trace back ray paths for each source–receiver pair. Travel times at each receiver are then recomputed using slowness values at the intersection points between the ray path and the traversed cells. A number of numerical tests with an array of different velocity models, mesh resolutions and mesh topologies have been carried out. These tests showed that an average relative error in the order of 0.1% can be achieved at a computational cost that is suitable for travel time inversion.

Type de document: Article
Mots-clés libres: travel time; seismic modelling; ray tracing; seismics; computing aspects
Centre: Centre Eau Terre Environnement
Date de dépôt: 17 avr. 2020 17:49
Dernière modification: 17 avr. 2020 17:49
URI: http://espace.inrs.ca/id/eprint/10080

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