1. Department of Geology and Geophysics; University of Wyoming; Laramie Wyoming 82071 USA
2. Department of Geology and Geophysics; Woods Hole Oceanographic Institution; Woods Hole Massachusetts USA
3. Jackson School of Geosciences; University of Texas Institute for Geophysics; Austin Texas USA
4. WesternGeco Ltd, Schlumberger House; Gatwick Airport UK
5. Escuela Centroamericana de Geología; University of Costa Rica; San Pedro Costa Rica
6. Department of Geological Sciences; University of Texas at El Paso; El Paso Texas USA
7. Instituto Costarricense de Electricidad; San José Costa Rica