Report on Piton de la Fournaise (France) — 27 November-3 December 2002
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 27 November-3 December 2002
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2002. Report on Piton de la Fournaise (France). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 27 November-3 December 2002. 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)
The eruption that began at Piton de la Fournaise on 16 November continued during 29 November to 3 December. On 29 November eruptive tremor increased by a factor of two, with 89 events recorded that day. On the 30th, 329 seismic events were recorded that were all located about 1 km a.s.l. beneath Dolomieu crater. A lava flow in the Grand Brûlé area approached the national road, crossing it around 2300. By about 0500 on 1 December the lava flow had reached the sea. At this time almost constant seismicity occurred at Piton de la Fournaise, with more than 1,500 earthquakes up to M 2.8 recorded. Eruption tremor was stable. Numerous long-period earthquakes were also recorded, indicating the presence of magma beneath the summit. On the morning of 2 December seismicity increased by about a factor of about three, and decreased the next day.
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.