Report on Piton de la Fournaise (France) — November 1983
Scientific Event Alert Network Bulletin, vol. 8, no. 11 (November 1983)
Managing Editor: Lindsay McClelland.
Piton de la Fournaise (France) Summit crater fissure eruption
Please cite this report as:
Global Volcanism Program, 1983. Report on Piton de la Fournaise (France) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 8:11. Smithsonian Institution.
Piton de la Fournaise
21.244°S, 55.708°E; summit elev. 2632 m
All times are local (unless otherwise noted)
The following quoted reports are from the OVPDLF. "Eruptive activity started 4 December at 0900, preceded by an increase in seismicity that began 20 November [corrected from 2 November]. From 20 November, the seismic events clustered at depths of about 1.5-5 km beneath the summit area. The maximum number of earthquakes was recorded 1 and 2 December, with 10 events (M <1) per day. The strain release was not very large. A seismic swarm began 4 December at 0642. About 300 events were recorded by 0859, when harmonic tremor began, and a few minutes later the eruption was seen. The initial eruption fissure was situated on the SSW flank of the central cone (Cratère Dolomieu). Activity at two segments of this fissure stopped during the evening. A second fissure zone opened at 1027 and stopped erupting about 1400; a third fissure opened at 1319 and ceased erupting about 0700 the next morning. The amount of lava extruded 4 December was estimated at 1 x 106 m3. The initial fissure was the most productive. Only weak deformation was measured before and during the eruption."
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: J. Lenat and F. Lalanne, OVPDLF; Univ. de la Réunion; J. LeMouel and J-L. Cheminée, IPG, Paris.