Report on Piton de la Fournaise (France) — 16 February-22 February 2005
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 16 February-22 February 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, 16 February-22 February 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)
A new period of heightened seismic activity began at Piton de la Fournaise on 17 February around 1300, consisting of about 100 seismic events within 90 minutes. After that, the number of events decreased, but recommenced at 1638 with several hundreds of events. Strong deformation was recorded at the same time by tiltmeters and the extensometer network. Eruption tremor began around 2035, becoming strong at 2050. The eruption site seemed to be situated close to Nez Coupé de Sainte Rose (on the N side of the volcano), and lava flows were observed in the Grand Brûlé area. According to a news report, the eruption ended on 19 February.
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.