David Fernández-Blanco¹, Sean F Gallen², Giovanni de Gelder³, Robin Lacassin⁴ and Rolando Armijo⁴, (1)Imperial College London, London, SW7, United Kingdom, (2)University of Michigan Ann Arbor, Ann Arbor, MI, United States, (3)Victoria University of Wellington, Wellington, New Zealand, (4)Institut de Physique du Globe de Paris, Paris, France