1. Lecturer in the Department of Geophysics, University of Edinburgh, Edinburgh EH9 3JZ Scotland
2. Research students in the Department of Geophysics, University of Edinburgh, Edinburgh EH9 3JZ Scotland
3. Professor of geography in the Department of Geography, University of Liverpool, Liverpool L69 3BX England
4. Research students in the Department of Geography, University of Liverpool, Liverpool L69 3BX England