Open AccessA traveltime reciprocity discrepancy in the Podvin & Lecomte time3d finite difference algorithm
Author(s) -
Tryggvason Ari,
Bergman Björn
Publication year - 2006
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.2006.02925.x
Subject(s) - reciprocity (cultural anthropology) , asymmetry , initialization , finite difference , finite difference method , mathematics , finite difference scheme , mathematical analysis , algorithm , physics , computer science , quantum mechanics , psychology , social psychology , programming language
SUMMARY We have found that the extensively used finite difference scheme time3d produces time fields which are ‘asymmetric’ in the sense that traveltimes computed to the right of the source are faster than traveltimes computed to the left. All finite difference schemes will, as they are approximations to the wave equation, to some extent fail to obey reciprocity perfectly. We show, however, that the errors in time3d may be significant—and unnecessarily large. An asymmetry in the point source initialization has been identified, and after correction time3d produces time fields with an improved reciprocity.