Report on Piton de la Fournaise (France) — 25 May-31 May 2016
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 25 May-31 May 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, 25 May-31 May 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 CO2 gas emission, deformation, and seismicity at Piton de la Fournaise began to slowly increase on 16 May, and then seismicity significantly increased at 1140 on 25 May. Tremor began at 0805 on 26 May, characteristic of an ongoing eruption, likely from a new fissure near Château Fort crater. Bad weather prevented visual observations of the area at first, though at 0900 ground observers confirmed a new eruption. Later that day scientists and reporters saw about six lava fountains (some were 40-50 m high) during brief aerial surveys and a cinder cone being built on a flat area at 1850 elevation about 1-1.5 km SE of Castle Crater. RSAM values significantly decreased at 1800, increased slightly, and then stabilized. On 27 May tremor levels significantly dropped at 0845 and then ceased at 1100. Signals indicative of degassing continued.
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.