1. 1Department of Geological Sciences, University of Texas, Austin, Texas 78712, USA
2. 2Observatatorio Vulcanológico y Sismológico de Costa Rica (OVSICORI), Universidad Nacional, Heredia 40101, Costa Rica
3. 3Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131, USA
4. 4Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA