OVPF reported that the eruption at Piton de la Fournaise, which began on 27 April from fissures at Rivals Crater, continued through 15 May. Field reconnaissance on 10 May revealed that activity was focused on the main cone, with some activity from a second cone that was ejecting material 10-20 m high. Over the next two days the crater of the main cone narrowed and lava projections at both cones became rare. Lava flows during this time were often confined to tubes, with some breakouts at the change in slope below Piton de Bert, about 3 km from the active cone. Burning vegetation as a result of the breakouts was visible on and at the foot of the rampart. Based on satellite data when surface flows were visible, lava emission rates were estimated to be about 1-2 cubic meters/second. Tremor intensity fluctuated over the week, with a sharp increase during 0500 and 0900 on 15 May.

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)