OVPF reported that the eruption at Piton de la Fournaise which began on 27 April from fissures at Rivals Crater continued through 22 May. Flowing lava was mostly confined to tubes, though spatter was ejected 20-30 m above the highest-elevation (and most active) vent of the three. Lava was weakly ejected from the lowest-elevation vent. CO2 concentrations at the summit were high. Inflation continued to be detected. Tremor levels had increased around 15 May but then began to steadily decrease on 18 May. Observers noted a significant decrease in activity on 19 May at the highest-elevation vent, and by 22 May was quiet; the main cone continued to spatter.

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)