1. British Geological Survey, Research Avenue South, Edinburgh, EH14 4AP, UK
2. Centre for Exploration Geoscience, Applied Geoscience Unit, Institute of Petroleum Engineering, Heriot–Watt University, Edinburgh, EH14 4AS, UK
3. Ocean & Earth Science, University of Southampton, National Oceanography Centre, European Way, Southampton, SO14 3ZH, UK
4. 10 Murrells Walk, Great Bookham, Surrey, KT23 3LP, UK