Report on Piton de la Fournaise (France) — 21 December-27 December 2005
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
21 December-27 December 2005
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2005. Report on Piton de la Fournaise (France). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 21 December-27 December 2005. Smithsonian Institution and US Geological Survey.
Piton de la Fournaise
21.244°S, 55.708°E; summit elev. 2632 m
All times are local (unless otherwise noted)
Following summit inflation that had been measured at Piton de la Fournaise since the last eruption on 29 November, a seismic crisis began beneath Dolomieu Crater on 26 December at 1444. During the next 2 hours, seismicity shifted to the NE in the direction of "Nez Coupe de Sainte Rose." A first fissure opened at 1715 at the NE base of Piton de la Fournaise. At 2200 eruptive fissures opened in the caldera wall ~500 m E of "Nez Coupe de Sainte Rose," and a lava flow traveled into the "Plaine des Osmondes." By the 28th, eruptive activity was almost constant and an aa lava flow slowly traveled in the "Grandes Brule" and had reached to within ~3 km of the national road.
Geological Summary. Piton de la Fournaise is a massive basaltic shield volcano on the French island of Réunion in the western Indian Ocean. 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 scarps formed at about 250,000, 65,000, and less than 5,000 years ago by progressive eastward slumping, leaving caldera-sized embayments open to the E and SE. Numerous pyroclastic cones are present on the floor of the scarps and their outer flanks. Most recorded eruptions have originated from the summit and flanks of Dolomieu, a 400-m-high lava shield that has grown within the youngest scarp, which is about 9 km wide and about 13 km from the western wall to the ocean on the E 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 outside the scarps.