Ile de La Réunion is located in the western Indian Ocean, 800 km east of Madagascar and represents the active centre of the 65 my old Deccan Trapp hotspot chain (Duncan, 1981, Morgan, 1981).The Island is formed by two shield volcanoes: the Piton des Neiges and the Piton de la Fournaise (Fig. 1).The older one, the Piton des Neiges erupted for the last …