Logo link to homepage

Report on Piton de la Fournaise (France) — August 1985

Piton de la Fournaise

Scientific Event Alert Network Bulletin, vol. 10, no. 8 (August 1985)
Managing Editor: Lindsay McClelland.

Piton de la Fournaise (France) Fissure activity resumes after 5-day hiatus

Please cite this report as:

Global Volcanism Program, 1985. Report on Piton de la Fournaise (France) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 10:8. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198508-233020

Piton de la Fournaise


21.244°S, 55.708°E; summit elev. 2632 m

All times are local (unless otherwise noted)

"The eruptive episode that began on 5 August ended 1 September. The major part of the aphyric basalt lava flow was emitted during the first 10 days. The lava front stayed at the bottom of the Grandes Pentes inside the Plaine des Osmondes (near the N caldera wall, figure 13). During the last week, small amounts of pahoehoe were emitted from tunnels at the foot of Cratère Faujas, about halfway between the central cone and the N caldera wall. Seismic tremor lasted for 10 days at a very low level.

Figure (see Caption) Figure 13. Sketch map of the summit caldera region of Piton de la Fournaise after Blum and others (1981).

"Deformation related to the opening of the 5 August fissure affected the summit and the flank of the Plaine des Osmondes. No significant deformation was recorded during August, but minor summit deflation was noted around the fissure zone.

Geological Summary. The massive Piton de la Fournaise basaltic shield volcano on the French island of RĂ©union in the western Indian Ocean is one of the world's most active volcanoes. Much of its more than 530,000-year history overlapped with eruptions of the deeply dissected Piton des Neiges shield volcano to the NW. Three calderas formed at about 250,000, 65,000, and less than 5000 years ago by progressive eastward slumping of the volcano. Numerous pyroclastic cones dot the floor of the calderas and their outer flanks. Most historical eruptions have originated from the summit and flanks of Dolomieu, a 400-m-high lava shield that has grown within the youngest caldera, which is 8 km wide and breached to below sea level on the eastern side. More than 150 eruptions, most of which have produced fluid basaltic lava flows, have occurred since the 17th century. Only six eruptions, in 1708, 1774, 1776, 1800, 1977, and 1986, have originated from fissures on the outer flanks of the caldera. The Piton de la Fournaise Volcano Observatory, one of several operated by the Institut de Physique du Globe de Paris, monitors this very active volcano.

Information Contacts: H. Delorme and J. Delarue, OVPDLF; P. Bachelery, Univ. de la Réunion.