1. Department of Earth and Planetary Sciences; University of California; Santa Cruz California USA
2. Institut de Physique du Globe de Strasbourg; Université de Strasbourg/CNRS; Strasbourg France
3. Observatorio Vulcanológica y Sismológico de Costa Rica; Universidad Nacional; Heredia Costa Rica
4. Department of Geology; University of South Florida; Tampa Florida USA
5. Jet Propulsion Laboratory; Pasadena California USA
6. School of Earth and Atmospheric Sciences; Georgia Institute of Technology; Atlanta Georgia USA