3-D multi-valued traveltime computation using a hybrid method

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Society of Exploration Geophysicists

Erscheinungsjahr:

2000

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Text

Beschreibung:

3-D prestack Kirchhoff migration is commonly done with first-arrival traveltimes computed with finite-difference eikonal solvers (FDESs). However, in complex velocity structures later-arrivals are also important for accurate imaging. Multi-valued traveltimes are commonly computed with ray tracing methods, but for 3-D velocity models the computational efficiency of ray tracing is low. Here, we propose a fast hybrid method for computing multi-arrival traveltimes in weakly smoothed 3-D velocity models. This method is based on the computation of first-arrival traveltimes with a FDES and the computation of later arrivals with the wavefront construction method (WFCM). The detection of later arrivals is done automatically. For the detection of later-arrival traveltimes and for traveltime interpolation we use a simple and robust technique which is based on the spherical approximation of the local WF between three rays. This technique also increases the computational efficiency of WFCM. Two examples show rhe efficiency and robustness of the hybrid method. The hybrid method is a better alternative to WFCM, since it is considerably faster and has a comparable accuracy. © 2000 Society of Exploration Geophysicists.

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Forschungsinformationssystem der UHH

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