Piton de la Fournaise and Karthala are both shield volcanoes in the southwest Indian Ocean. This publication summarizes the work done on these very active basaltic volcanoes. Piton de la Fournaise has a long history of scientific research and monitoring, with many data collected during recent eruptions. It is certainly one of the most studied volcanoes in the world. The work presented in this monograph includes geological, geophysical, geochemical and petrological aspects, but also studies on physical geography, natural hazards and the sociological and behavioural approaches.
If the Karthala volcano is much less known, it offers an interesting complementarity with Piton de la Fournaise. Structurally close to the volcanoes of Hawaii, it differs by its more alkaline magmas and less frequent activity. Also monitored for more than 25 years, it has experienced extraordinary eruptions in recent years.