Report on Piton de la Fournaise (France) — 30 December-5 January 2010
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 30 December-5 January 2010
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2009. Report on Piton de la Fournaise (France). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 30 December-5 January 2010. 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)
OVPDLF reported that a seismic crisis at Piton de la Fournaise on 29 December was characterized by numerous earthquakes in the area W and NW of Dolomieu crater (max M 3), at depths of 1.1-2.2 km below the summit. Deformation was also detected. On 31 December, OVPDLF reported decreased seismicity and fewer landslides within Dolomieu crater on 30 and 31 December. On 2 January, an eruption from a fissure near the top of the W crater rim, preceded by a seismic crisis, produced lava fountains a few tens of meters high and lava flows in Dolomieu crater. Large landslides in Bory crater (W) along with the fissure eruption generated ash and gas plumes that rose above Piton de la Fournaise. During 2-3 January, seismicity and the number of landslides decreased. As of 4 January, the lava flows covered about 80 percent of the crater floor. Lava fountaining was still visible.
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.