OVPF reported that a seismic crisis at Piton de la Fournaise began at 0700 on 11 August and was accompanied by rapid deformation. The locations of the earthquakes and area of deformation indicated that magma rose from deep under the SE edge of Dolomieu Crater to beneath the E and SE flanks. Tremor began around 1620, indicating the likely start of this year’s fourth eruption, though inclement weather conditions prevented visual confirmation. The Alert Level was raised to 2-2. On 12 August OVPF confirmed that fissures had opened in the E part of l’Enclos Fouqué, SE of the upper Grandes Pentes. Scientists saw two fissures, about 1.4 km apart, at 1,700 and 1,500 m elevation during an overflight on 13 August. Only the lowest elevation fissure was active. Three distinct cones along the fissure fed lava flows that merged into one which traveled to 665 m elevation and caused small fires as it burned local vegetation.

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)