Report on Piton de la Fournaise (France) — 3 December-9 December 2003
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
3 December-9 December 2003
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2003. Report on Piton de la Fournaise (France). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 3 December-9 December 2003. 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 around an hour of seismicity an eruption began on 7 December at 1535 in Piton de la Fournaise's Dolomieu crater. Lava fountaining to tens of meters was observed from two fractures on the SE crater floor. Two new fractures were also observed on the S crater rim that did not produce lava. The eruption decreased rapidly over the night of 7-8 December. By 8 December at ~1400 small incandescent lava flows and rock fall on the S crater wall were observed. By the night of 8 December the eruption ceased but strong degassing and fluctuating seismicity continued. New lava covered ~40% of the floor of Dolomieu crater. The eruption was preceded by a seismic swarm on 6 November that was followed by ~30 cm of steady uplift and 10-20 earthquakes recorded per day.
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.