Report on Piton de la Fournaise (France) — 2 September-8 September 2015
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
2 September-8 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, 2 September-8 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)
OVPDLF reported that scientists conducting fieldwork at Piton de la Fournaise during 31 August-1 September observed one active cone (20 m high) filled with a lava lake. Fluctuating lava fountains rose 15-20 m above the lake surface and gas bubbles exploded. Lava traveled through a 50-m-long lava channel and was a total of 1 km long. During 1-2 September seismicity increased, and the lava flow length increased to 2 km. Tremor remained high on 5 September. The lava lake was in two separate but side-by-side vents and lava fountains were lower compared to recent days. Five small lava flows were near the foot of the cone; four were 30 m long and the fifth was 1 km long. Tremor levels started to decline on 7 September but remained at a high level through 9 September.
Geological Summary. Piton de la Fournaise is a massive basaltic shield volcano on the French island of Réunion in the western Indian Ocean. 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 scarps formed at about 250,000, 65,000, and less than 5,000 years ago by progressive eastward slumping, leaving caldera-sized embayments open to the E and SE. Numerous pyroclastic cones are present on the floor of the scarps and their outer flanks. Most recorded eruptions have originated from the summit and flanks of Dolomieu, a 400-m-high lava shield that has grown within the youngest scarp, which is about 9 km wide and about 13 km from the western wall to the ocean on the E 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 outside the scarps.