Report on Piton de la Fournaise (France) — 7 August-13 August 2019
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 7 August-13 August 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, 7 August-13 August 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 0700 on 11 August and was accompanied by rapid deformation. The locations of the earthquakes and area of deformation indicated that magma rose from deep under the SE edge of Dolomieu Crater to beneath the E and SE flanks. Tremor began around 1620, indicating the likely start of this year’s fourth eruption, though inclement weather conditions prevented visual confirmation. The Alert Level was raised to 2-2. On 12 August OVPF confirmed that fissures had opened in the E part of l’Enclos Fouqué, SE of the upper Grandes Pentes. Scientists saw two fissures, about 1.4 km apart, at 1,700 and 1,500 m elevation during an overflight on 13 August. Only the lowest elevation fissure was active. Three distinct cones along the fissure fed lava flows that merged into one which traveled to 665 m elevation and caused small fires as it burned local vegetation.
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.