1. University College London, London WC1E6BS, UK.
2. University of Cambridge, Cambridge CB23EQ, UK.
3. Università di Palermo, 90123 Palermo, Italy.
4. GasLAB, Universidad de Costa Rica, San José, Costa Rica.
5. Chalmers University of Technology, Göteborg, Sweden.
6. Heidelberg University, Heidelberg, Germany.
7. Max Planck Institute for Chemistry, Mainz, Germany.
8. Michigan Technological University, Houghton, MI 49931, USA.
9. University of Bristol, Bristol, BS8 1TR, UK.
10. Universidad Nacional, Heredia, 40101-3000 Costa Rica.
11. University of New Mexico, Albuquerque, NM 87131, USA.
12. University of Saskatchewan, Centre for Hydrology, Canmore, Alberta T1W 3G1, Canada.
13. INGV, Osservatorio Etneo, Sezione di Catania, 95125 Catania, Italy.
14. Johannes Gutenberg-Universität, Mainz 55128, Germany.
15. University of Manchester, Manchester, M13 9PL, UK.
16. Rabaul Volcanological Observatory, Rabaul, Papua New Guinea.
17. Victoria University of Wellington, Wellington 6012, New Zealand.