Edwin Baynes, University of Auckland, Auckland, New Zealand, Heide Friedrich, University of Auckland, Civil and Environmental Engineering, Auckland, New Zealand, Dimitri Lague, CNRS, Paris Cedex 16, France, Philippe Steer, UMR CNRS 6118, University of Rennes 1, Géosciences Rennes, Rennes, France and Stephane Bonnet, Universite de Toulouse, Toulouse, France