1. Department of Earth Sciences, University of Oxford, South Parks Road, Oxford, UK
2. Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, UK
3. Department of Earth Sciences, Durham University, Science Labs, Durham, UK
4. Research Laboratory for Archaeology and the History of Art, University of Oxford, South Parks Road, Oxford, UK
5. Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Vesuviano, via Diocleziano 328, Napoli, Italy
6. School of Earth Sciences, University of Bristol, Queens Road, Bristol, UK