1. College of Science, Swansea University, Swansea, UK
2. Bristol Glaciology Centre, Bristol University, Bristol, UK
3. Department of Geophysics, Colorado School of Mines, Golden, Colorado, USA
4. ISTerre, UMR 5275, Université de Savoie, CNRS, Le Bourget du Lac, France
5. School of Geosciences, University of Edinburgh, Edinburgh, UK