Report on Piton de la Fournaise (France) — 23 September-29 September 2015
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 23 September-29 September 2015
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2015. Report on Piton de la Fournaise (France). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 23 September-29 September 2015. 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)
On 24 September OVPDLF reported that, since 20 September, seismicity, deformation, and gas emissions at Piton de la Fournaise stabilized but remained at high levels. The cone was 30 m high; lava fountains were lower and less frequently observed. A white water vapor plume rose from the vents. Lava flows continued to be active, mainly traveling as far as 3 km S and less than 3 km E. During 22-23 September a new lava tube formed to the W of the lava field.
Since the beginning of the eruption deformation data indicated no deflation. Early on in the eruption the flow rate decreased from 60 cubic meters per second to between 5 and 10; the rate declined during 28 August-7 September and then increased again, starting on 7 September.
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.