Report on Piton de la Fournaise (France) — 14 September-20 September 2022
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
14 September-20 September 2022
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2022. Report on Piton de la Fournaise (France). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 14 September-20 September 2022. 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 a seismic crisis at Piton de la Fournaise began at 0623 on 19 September. Volcanic tremor located beneath the SSW part of the caldera began at 0748, likely signifying the arrival of magma at the surface, though weather clouds prevented visual confirmation from webcams. Pelotons de Gendarmerie de Haute Montagne (PGHM) teams that were on-site to evacuate people from inside the caldera observed lava fountains 20-30 m high rising from a fissure that had opened E of Piton Kala Pélé. The eruption was confined to the caldera, so the Alert Level was raised to 2-1 (“2” is the highest level of a 3-level scale and “-1” denotes the lowest of three sub-levels). By 20 September lava fountaining had decreased and the focus of the eruption was at the lower part of the fissure. Sulfur dioxide emissions peaked at an estimated 8,000 tons per day at the beginning of the eruption and then decreased to about 2,300 tons per day during 20-21 September.
Geological Summary. 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.