1. Geoscience Institute, Federal University of Bahia, Salvador, Brazil
2. Post-graduation Program in Geochemistry: Petroleum and Environment, Federal University of Bahia, Salvador, Brazil
3. Université de Bordeaux, CNRS, Bordeaux, France
4. Physics Institute, Federal University of Bahia, Salvador, Brazil
5. Image Processing Division, National Institute for Space Research, São J. dos Campos, Brazil