The Observatoire Volcanologique du Piton de la Fournaise reported sharp increase in seismic activity beneath Piton de la Fournaise, a shield volcano which forms much of the eastern part of Réunion Island, an island in the western Indian Ocean which forms a department of France, starting slightly after 3.20 pm on Saturday 16 February 2019, and persisting for slightly over an hour. This resumed slightly after 9.15 am on Monday 18 February, and was accompanied by rapid deformation on the eastern flank of the volcano, and eventually the opening of a fissure on that flank from which a lava fountain emerged, reaching heights of about 30 m, and resulting in a lava flow that reached about 1900 m down the flank of the volcano. This continued until about 10.00 pm. Further earthquakes and gas emissions were recorded on 19 February, and on the 20th an overflight by vulcanologists from the Observatoire Volcanologique du Piton de la Fournaise recorded another fissure on the eastern flank.
A lava flow on the eastern flank of Piton de la Fournaise on 20 February 2019. Le Chaundron de Vulcan.
Piton de la Fournaise is believed to have been active for about 530 000 years, though its geology is complicated to unravel as lava flows are interbedded with those from Piton des Neiges, a larger, older and now extinct volcano to the northwest, which is responsible for the formation of about two thirds of the island. The island sits on the Réunion Hotspot, a deep mantle plume which is thought to have been active for about 66 million years, originally forming under what is now northeastern India, where it was responsible for the Deccan Traps flood basalts, then moving southward across the Indian Ocean (or more precisely sitting still while the continental plate upon which India and the Indian Ocean sit moves to the north), over time forming the Laccadive Islands, the Maldives, the Seychelles, Rodrigues Island, Mauritius and Réunion.
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