Nadine Igonin, University of Calgary, Calgary, AB, Canada, David W S Eaton, University of Calgary, Geoscience, Calgary, AB, Canada, William L Ellsworth, Stanford University, Stanford, CA, United States, Grzegorz Kwiatek, Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Potsdam, Germany and James Verdon, University of Bristol, School of Earth Science, Bristol, United Kingdom