Report on Piton de la Fournaise (France) — 9 January-15 January 2002
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 9 January-15 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, 9 January-15 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)
The eruption that began at Piton de la Fournaise on 5 January, continued through 15 January. There was a decrease in tremor during 7-11 January, with as few as 8 small earthquakes recorded per day at about 1-km depth. On 12 January tremor increased by a factor of two in comparison to the previous day and earthquakes were recorded about 4 km beneath the Plaine des Osmondes, near the N caldera wall. During the evening of 12 January, a new fissure opened at the base of the rampart in the lower part of the Plaine des Osmondes. Lava flowed from the fissure down into the Grand Brûlé close to the northern rampart. On 14 January lava flowed across the National Highway on its way to the ocean, entering it at 1540. By 15 January tremor was stable and about 100 earthquakes were recorded over a 24-hour period on the N side of the volcano. At 0600 a swarm of low-frequency earthquakes began near Bois-Blanc, a village on the island's E coast, NE of Plaine des Osmondes.
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.