1. Cooperative Institute for Research in the Environmental Sciences and Department of Geological Sciences; University of Colorado Boulder; Boulder Colorado USA
2. Now at Tricon Geophysics, Inc.; Denver Colorado USA
3. Now at Facultad de Minas, Universidad Nacional de Colombia sede Medellín; Medellín Colombia
4. Lamont Doherty Earth Observatory; Columbia University; Palisades New York USA
5. Department of Earth Science; University of California; Santa Barbara California USA