1. University of Oxford Department of Earth Sciences, , South Parks Road, Oxford, OX1 3AN, UK
2. The University of the West Indies , St. Augustine, Seismic Research Centre, Trinidad and Tobago
3. School of Science Department of Earth and Planetary Science, , The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
4. Institute of Geophysics , Czech Academy of Sciences, Boční II 1401,141 31 Prague 4, Czech Republic
5. School of Environment , Earth and Ecosystem Sciences, The Open University, Walton Hall, Milton Keynes, Buckinghamshire MK7 6AA, UK
6. Royal Holloway University of London Department of Earth Sciences, , Egham, Surrey, TW20 0EX, UK