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. 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.