Introduction
Shield volcano in southeast Réunion, Indian Ocean
Piton de la FournaisePiton de la Fournaise is a shield volcanoHighest pointElevation2,621 m (8,599 ft)Prominence1,027 m (3,369 ft)ListingRibuCoordinates21°14′33″S 55°42′32″E / 21.24250°S 55.70889°E / -21.24250; 55.70889NamingEnglish translationPeak of the FurnaceLanguage of nameFrenchGeographyPiton de la FournaiseRéunion, Indian Ocean
GeologyRock age530,000 yearMountain typeShield volcanoLast eruptionJanuary 2026ClimbingFirst ascent21 September 1751
Orthoimagery
Piton de la Fournaise (French: [pitɔ̃ də la fuʁnɛz]; 'Peak of the Furnace') is a shield volcano on the eastern side of Réunion island, a French overseas department and region, in the Indian Ocean. It is currently one of the most active volcanoes in the world, along with Kīlauea in the Hawaiian Islands, Stromboli and Etna in Italy and Mount Erebus in Antarctica. A previous eruption began in August 2006 and ended in January 2007. The volcano erupted again in February 2007, on 21 September 2008, on 9 December 2010, which lasted for two days, and on 1 August 2015. The volcano is located within Réunion National Park, a World Heritage Site.
Residents of Réunion sometimes refer to Piton de la Fournaise simply as le Volcan ("the Volcano"). It is a major tourist attraction.
Geology
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The uppermost section of the volcano is occupied by the Enclos Fouqué, a caldera 8 kilometres (5.0 mi) wide. High cliffs, known as remparts in French, form the caldera's rim. The caldera is breached to the southeast towards the sea. The eastern flank of the volcano is unstable and is in the initial stages of failure. It will eventually collapse into the Indian Ocean, possibly causing a megatsunami in the event of a cataclysmic debris flow. There is evidence of earlier failures on the submerged flanks and surrounding abyssal plain. The lower slopes are known as the Grand Brûlé ("Great Burn"). Most volcanic eruptions are confined to the caldera.
Inside the caldera is a 400-metre-high (1,300 ft) lava shield named Dolomieu. At the top of this lava shield are Bory Crater (Cratère Bory) and Dolomieu Crater (Cratère Dolomieu), which is by far the wider of the two and named for French geologist Déodat Gratet de Dolomieu.
Topographic map showing the volcano and surrounding terrain
Many craters and spatter cones can be found inside the caldera and on the higher flanks of the volcano. Lavas with high concentrations of iridium are routinely ejected through these vents. By the trailhead of the summit path there lies a small noteworthy crater called Formica Leo, named for its resemblance to the sand pit trap of an antlion.
Located outside of the main caldera is Commerson Crater, an inactive caldera notable for receiving intense rainfall, particularly during tropical storms. During Cyclone Hyacinthe in January 1980, it received 6,433 millimetres (253.3 in) of rainfall in 15 days, the most precipitation produced by a tropical cyclone in a single location.
Some beaches in the proximity of the volcano are greenish in color, due to olivine sand derived from picrite basalt lavas. The Grand Brûlé is formed from solidified lava flows accumulated over hundreds of thousands of years; the most recent ones are often the darkest and most vegetation-free, while older ones can be covered by dense natural vegetation.
This volcano is over 530,000 years old, and for most of its history, its flows have intermingled with those from Piton des Neiges, a larger, older and heavily eroded inactive volcano which forms the northwest two-thirds of Réunion Island. There were three episodes of caldera collapses 250,000, 65,000 and 5,000 years ago. The volcano was formed by the Réunion hotspot, which is believed to have been active for the past 66 million years. There is evidence for explosive eruptions in the past. One explosive eruption about 4,700 years ago may have had a VEI (Volcanic Explosivity Index) of 5, which is the same as the 18 May 1980 eruption of Mount St. Helens.
