ACKNOWLEDGMENTS

I would like to thank BP Exploration for providing the field data set used in this paper. These data were acquired by Jerry M. Harris while he was at BP. I thank him and also Francis Muir, who have been a source of important and challenging suggestions that have enormously contributed to my research. Spyros Lazaratos picked the first arrival traveltimes. I thank Carlos Cunha-Filho and Lin Zhang for their help with vplot. Finally, I thank INTEVEP, S.A for financial support.