1. Department of Geological Sciences; University of North Carolina at Chapel Hill; Chapel Hill North Carolina USA
2. Department of Terrestrial Magnetism; Carnegie Institution for Science; Washington District of Columbia USA
3. Department of Geosciences; University of Arizona; Tucson Arizona USA
4. Department of Geology and Geophysics; Yale University; New Haven Connecticut USA
5. Instituto Geofísico del Perú; Lima Perú