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Report on Piton de la Fournaise (France) — 22 December-28 December 2021


Piton de la Fournaise

Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
22 December-28 December 2021
Managing Editor: Sally Kuhn Sennert

Please cite this report as:

Global Volcanism Program, 2021. Report on Piton de la Fournaise (France). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 22 December-28 December 2021. Smithsonian Institution and US Geological Survey.

Weekly Report (22 December-28 December 2021)

Piton de la Fournaise

France

21.244°S, 55.708°E; summit elev. 2632 m

All times are local (unless otherwise noted)


OVPF reported that an eruption at Piton de la Fournaise began at 0105 on 22 December on the S flank, SE of Piton Kala Pélé and SW of Château Fort. Four fissures opened and produced lava fountains, with the lowest point of the eruption at an elevation of 2,000 m. By the evening, the eruption was focused at 2,030 m elevation where a cone was forming around the vent. The lava effusion rate based on satellite data was an estimated 4-7 meters per second, with peak rates of 22 meters per second, during 22-23 December. By 0930 on 23 December the cone was 10 m high and low lava fountains intermittently rose above the crater rim. Lava flowed from an opening at the base of the cone, though a lava tube was beginning to form; lava had descended 2.2 km SSE from the main vent. During 24-25 December lava traveled from the base of the cone hundreds of meters through a tube before it emerged and advanced in a single channel; the front of the flow had advanced slowly, only traveling an additional 300 m by 25 December. During 25-26 December the lava tube broke open and lava was again visible emerging from the base of the cone. The flow rate was between 2 and 27 meters per second, averaging 5 meters per second. A second vent at the base of the cone was visible in the morning of 27 December and lava was again flowing through a tube and then emerging downstream. Lava fountaining continued with material occasionally ejected less than 15 m above the cone during 27-28 December. The effusion rate was an estimated 2-8 meters per second, based on satellite data. The end of the lava flow had not notably advanced since the day before.

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.

Source: Observatoire Volcanologique du Piton de la Fournaise (OVPF)