Invited contribution by J. E. Daniell, one of the EGU Outstanding Young Scientists Award winners 2010.

Center for Disaster Management and Risk Reduction Technology (CEDIM) and Geophysical Institute, KIT, Hertzstrasse 16, 76187, Karlsruhe, Germany

General Sir John Monash Scholar, The General Sir John Monash Foundation, Level 5, 30 Collins Street, Melbourne, Victoria, 3000, Australia