Report on Piton de la Fournaise (France) — 12 September-18 September 2018
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 12 September-18 September 2018
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2018. Report on Piton de la Fournaise (France). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 12 September-18 September 2018. 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)
OVPF reported that after several hours of increased seismicity at Piton de la Fournaise a seismic crisis began at 0145 on 15 September, accompanied by rapid deformation. Tremor began at 0425, contemporaneous with the opening of fissures on the S flank near Rivals Crater. Around 1000 an estimate of the lava flow rate, based on satellite data, was 30 cubic meters per second. During an overflight about an hour later observers noted five fissures. The central fissure was the most active, producing lava fountains 30 m high; two lava flows that merged downstream had already flowed more than 2 km towards the wall of the Enclos Fouqué. By the afternoon of 16 September the estimated flow rate was between 2.5 and 7 cubic meters per second. Only three vents were active and a cone had started to form. Lava flows continued to advance during 16-18 September.
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.