OVPF reported that the eruption at Piton de la Fournaise that began on 19 September, E of Piton Kala Pélé, was ongoing during 21-27 September. Gas plumes drifted SW, WSW, W, NNW, and were detected as far as 200 km from the vent in a 27 September satellite image. The active cone on the low end of the fissure ejected lava to low heights above the cone’s rim. Lava flows from the base of the cone formed two main flows that traveled SE and ESE. Lava flowed through sections of tubes mainly located along the first kilometer of both flows. Average daily lava-flow rate estimates varied from 1 to 8 meters per second based on satellite data. The SE flow front had advanced to the Château Fort crater area, reaching 2,000 m elevation on 24 September, though that flow had stopped advancing by 26 September. The eruption was confined to the caldera, so the Alert Level remained at 2-1 (“2” is the highest level of a 3-level scale and “-1” denotes the lowest of three sub-levels).

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.

Source: Observatoire Volcanologique du Piton de la Fournaise (OVPF)