1. Laboratory of Geophysical Simulation and Inversion, Applied Physics Department, Engineering Faculty, Universidad Central of Venezuela, Caracas, CA 1060, Venezuela. E-mail: boschm@ucv.ve.
2. Avenida Universidad, esquina El Chorro, torre MCT, piso 17, Dirección General de Coordinación de Programas, Caracas, Venezuela. E-mail: rmeza@mct. gov.ve.
3. Computer Sciences Research Center, Geology, Math and Computer Science Building, San Diego State University, 5500 Campanile Drive, San Diego, California 92182. E-mail: rjimenea@sciences.sdsu.edu.
4. Directoria Ambev Venezuela, Avenida Principal de Boleita, Calle Miraima, Edificio Draza, Piso 2, Boleita Norte, Venezuela. E-mail: alfredohonig@brahma. com.ve.