Report on Piton de la Fournaise (France) — 7 September-13 September 2016
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 7 September-13 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, 7 September-13 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)
OVPDLF reported that seismicity at Piton de la Fournaise was low in August, following an elevated number of volcano-tectonic events the second half of July. Gas emissions were low and dominated by water vapor; CO2 emissions had been elevated during 21-27 July. Inflation had stopped in early August and slight deflation was detected through 2 September.
Seismicity increased on 10 September, and elevated levels of SO2 at fumaroles were detected. A seismic crisis began at 0735 on 11 September, characterized by several earthquakes per minute. Deformation suggested magma migrating to the surface. Volcanic tremor began at 0841, synonymous with the beginning of the eruption. Several fissures opened in the N part of the l'Enclos Fouqué caldera, between Puy Mi-côte and the July 2015 eruption site, and produced a dozen 15-30-m-high lava fountains distributed over several hundred meters. Tremor levels decreased by a factor of four, and by 2100 were stable. The eruption continued on 12 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.