Report on Piton de la Fournaise (France) — June 1998
Bulletin of the Global Volcanism Network, vol. 23, no. 6 (June 1998)
Managing Editor: Richard Wunderman.
Piton de la Fournaise (France) April-June lava flows on Plaines des Osmondes and beyond
Please cite this report as:
Global Volcanism Program, 1998. Report on Piton de la Fournaise (France) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 23:6. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199806-233020.
Piton de la Fournaise
21.244°S, 55.708°E; summit elev. 2632 m
All times are local (unless otherwise noted)
Crater activity was vigorous and variable during late April. It included lava fountains and gas-piston events. After that, and as late as mid-July, observers saw only occasional projections of lava.
The first lava flows emerging into the Plaine des Osmondes blocked the outflow of subsequent lavas from Piton Kapor (see maps, BGVN 23:02 and 23:03). Later flows went N and followed the caldera wall E towards the Plaine des Osmondes, often traveling through lava tubes. Overflow and accumulation of basalt around Piton Kapor formed three distinct, nearly horizontal plateaus several hundred meters across and up to 40-50 m thick. Magne crater, formed in 1972 only 400 m below Piton Kapor has almost disappeared beneath the new lava flows. The emitted volume was estimated at 40-50 x 106 m3, which would mark this eruption as one of the most voluminous during this century. Piton Kapor is the largest and most noteworthy cone within the caldera.
Lava flows overran the Plaine des Osmondes on 6 July. The overflow went down to Grandes Pentes, burning some vegetation, bushes, and trees. Its maximum length reached ~10 km. The front of the flow was at ~350 m altitude, only 2 km from the national road. No further advance of the front has been observed.
Tremor decreased through April until mid-May and then remained constant until 10 July. During 10-18 July tremor increased and was more unstable, probably due to collapse of lava tubes. Normal levels of tremor resumed in late 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: Thomas Staudacher, Observatoire Volcanologique du Piton de la Fournaise (OVPF), 14 RN3, le 27Km, 97418 La Plaine des Cafres, La Réunion, France.