Report on Piton de la Fournaise (France) — 4 July-10 July 2001
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 4 July-10 July 2001
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2001. Report on Piton de la Fournaise (France). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 4 July-10 July 2001. 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 started on 11 June stopped on 7 July after 1 week of increased tremor. On 3 July tremor and the intensity of local earthquakes increased. The earthquakes had magnitudes less than 3 and were located under Dolomieu crater at a depth near sea level. On 6 and 7 July two aa lava flows in the Grand Brûlé area crossed the national highway. On 7 July the end of the eruption was marked by the disappearance of the tremor and a dramatic decrease in the intensity of local earthquakes.
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.