Report on Piton de la Fournaise (France) — 24 July-30 July 2019
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 24 July-30 July 2019
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2019. Report on Piton de la Fournaise (France). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 24 July-30 July 2019. 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 0513 on 29 July and was accompanied by rapid deformation. Tremor beneath the N flank began to be recorded around 1200, indicating the likely start of the eruption, though inclement weather conditions prevented visual confirmation. OVPF visited the site and conducted helicopter overflights around 1630 and observed three active fissures, with a total length of 450 m, that crossed the July 2018 flows on the NW flank (600 m from the Formica Léo). The fissures produced 20-30-m-high lava fountains and ‘a’a lava flows that traveled no more than 500 m. After a gradual decline, volcanic tremor ceased at 0430 on 30 July signaling the end of the eruption.
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.