Report on Piton de la Fournaise (France) — 11 July-17 July 2018
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
11 July-17 July 2018
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2018. Report on Piton de la Fournaise (France). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 11 July-17 July 2018. 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 inflation at Piton de la Fournaise began at the beginning of July. An abrupt seismic increase was detected at 2340 on 12 July, coupled with rapid deformation. Tremor beneath the N flank appeared at about 0330 on 13 July and gradually increased, and webcams recorded the emergence of lava at 0430. The eruption originated from four fissures which had a total length of 500 m, and were located upstream of Chapelle de Rosemont. Tremor intensity peaked at 0600. By 0800 all four fissures were ejecting lava as high as 20 m, and ‘a’a flows had traveled over 200 m. The most upstream fissure was inactive by 1230. After a period of decreasing tremor and pulsating gas emissions the eruption ended at 2200. Strong seismicity continued to be recorded on 14 July, but then decreased over the next two days. The lava flows covered about 400 m of the trail leading to the summit.
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.