1. Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA. E-mail: accardo@ldeo.columbia.edu
2. Department of Earth and Environmental Sciences, Tulane University, New Orleans, LA 70118, USA
3. Department of Geosciences, The Pennsylvania State University, State College, PA 16802, USA
4. Geological Survey of Tanzania, Dodoma, Tanzania
5. Geological Survey Department of Malawi, Zomba, Malawi
6. Department of Geology, University of Dar es Salaam, Dar es Salaam, Tanzania
7. National Oceanography Centre Southampton, University of Southampton, Southampton S017 1BJ, United Kingdom
8. Dipartimento di Scienzedella Terra, Universita degli Studi di Firenze, Florence 50121, Italy
9. Department of Earth Sciences, Syracuse University, New York, NY 13210, USA
10. Department of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia
11. School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, United Kingdom
12. Alaska Volcano Observatory, U.S. Geological Survey, Anchorage, AK 99775, USA