Report on Piton de la Fournaise (France) — 2 January-8 January 2002
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 2 January-8 January 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, 2 January-8 January 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)
Following several months of precursory activity an eruption began at Piton de la Fournaise on 5 January at 2300. Increased seismicity was recorded about a week before the start of the eruption; there were 17, 49, 62, and 70 earthquakes recorded on 26, 27, 29, and 30 December, respectively. The earthquakes were mainly located N of Dolomieu Crater at depths of 0.5-1.5 km with a maximum magnitude of 2.2. Inflation was recorded on 28 December and extensometers at Magnes and Châeau Fort recorded 0.28-mm-wide cracks on 31 December. The eruption that began on 5 January consisted of fire fountaining and lava flowing from four cracks that opened in the NE part of l'Enclos Fouqué caldera. By 6 January only two cracks remained active and lava flows reached ~1,100 m elevation. On 7 and 8 January tremor strongly decreased, but other seismicity persisted.
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.