Report on Piton de la Fournaise (France) — July 1979
Scientific Event Alert Network Bulletin, vol. 4, no. 7 (July 1979)
Managing Editor: David Squires.
Piton de la Fournaise (France) Small lava flows from two radial fissures
Please cite this report as:
Global Volcanism Program, 1979. Report on Piton de la Fournaise (France). In: Squires, D. (ed.), Scientific Event Alert Network Bulletin, 4:7. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN197907-233020.
Piton de la Fournaise
21.244°S, 55.708°E; summit elev. 2632 m
All times are local (unless otherwise noted)
A small eruption began when two radial fissures opened almost simultaneously on the N and S flanks of Cratère Dolomieu (the central crater) at about 1845 on 13 July. A line of three small fountains, each 50 m high, formed along the N flank fissure and aa lava flowed 400 m downslope. N flank activity ended at about 2200. Ten spatter cones were generated by the 0.5-km-long S-flank fissure and a second aa flow traveled 1.5 km before the eruption stopped at 1130 on 14 July.
Geologic Background. The massive Piton de la Fournaise basaltic shield volcano on the French island of Réunion 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: M. Krafft, Cernay.