1. Norwegian Geotechnical Institute (NGI), Sognsveien 72, Oslo 0806, Norway
2. Department of Geoscience, University of Oslo, Sem Sælands Vei 1, Oslo 0371, Norway
3. Department of Earth, Ocean and Ecological Sciences, University of Liverpool, Jane Herdman Building, 4 Brownlow Street, Liverpool L69 3GP, UK