Amaury Bouyon, Institut de Physique du Globe de Paris, Paris, France, Joao Mata, IDL, Faculdade de Ciências, Universidade de Lisboa, Geologia, Lisboa, Portugal, Martin Bromann Klausen, University of Stellenbosch, Stellenbosch, South Africa, Sebastian Tappe, University of Johannesburg, Auckland Park, South Africa and Pierre Cartigny, Institut de Physique du Globe de Paris, Sorbonne-Paris Cité, Université Paris Diderot, CNRS, Paris, France