Report on Piton de la Fournaise (France) — 14 September-20 September 2016
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 14 September-20 September 2016
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2016. Report on Piton de la Fournaise (France). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 14 September-20 September 2016. 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 volcanic tremor at Piton de la Fournaise stabilized during 14-17 September. Field observations on 15 September revealed that the two volcanic cones that had formed on the lower part of the fissures had begun to coalesce. Lava from the northernmost cone flowed N and NE, and by 0900, was active midway between Piton Partage and Nez Coupé de Sainte Rose. The height of the lava fountains grew in the afternoon, rising as high as 60 m, likely from activity ceasing at the southernmost cone and focusing at one main cone. On 16 September the main cone continued to build around a 50-m-high lava fountain; lava flows from this vent traveled NE. Tremor rose during the night on 17 September, and then fell sharply at 0418 on 18 September, indicating the end of surficial activity. During 11-18 September the erupted volume was an estimated 7 million m3.
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.