1. Department of Earth Science and Engineering, Imperial College London, London SW7 2BP, United Kingdom
2. The Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom
3. University of Wuppertal, Gaußstraße 20, D-42119 Wuppertal, Germany and Jülich Supercomputing Centre, Forschungszentrum Jülich, D-52425 Jülich, Germany