1. School of Geosciences, University of the Witwatersrand, Private Bag 3 - 2050 Wits, Johannesburg, South Africa. E-mail: nyonyfenitra@gmail.com
2. Institut et Observatoire de Géophysique d’Antananarivo, Université d’Antananarivo, Ambohidempona - B.P 3843, Antananarivo 101, Madagascar
3. Department of Geosciences, Penn State University, 503 Deike Building, University Park, PA 16802, USA
4. Department of Earth and Planetary Sciences, Washington University in St. Louis, Campus Box 1169, 1 Brookings Dr, Saint Louis, MO 63130-4899, USA
5. Deutsches GeoForschungsZentrum (GFZ), Telegrafenberg, D-14473 Potsdam, Germany
6. Departamento de Geofísica & Programa de Pós-Graduação em Geodinâmica e Geofísica, Universidade Federal do Rio Grande do Norte, Natal, Brazil