Image Source: Vulcani & Vulcani Online The massive Piton de la Fournaise basaltic shield volcano on the French island of Réunion in the western Indian Ocean is one of the world's most active volcanoes. Much of its >530,000 year history overlapped with eruptions of the deeply dissected Piton des Neiges shield volcano to the NW. Three calderas formed at about 250,000, 65,000, and less than 5000 years ago by progressive eastward slumping of the volcano. Numerous pyroclastic cones dot the floor of the calderas and their outer flanks. Most historical eruptions have originated from the summit and flanks of Dolomieu, a 400-m-high lava shield that has grown within the youngest caldera, which is 8 km wide and breached to below sea level on the eastern 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 on the outer flanks of the caldera. The Piton de la Fournaise Volcano Observatory, one of several operated by the Institut de Physique du Globe de Paris, monitors this very active volcano. (Description courtesy of the Global Volcanism Program) ASAR interferograms of the Piton de la Fournaise volcano exhibit clear fringes patterns centred on the Soufriere pit crater, on the external northern flank of the summit Dolomieu caldeira. The range change pattern is asymmetric with respect to the eruptive fissures. Click the image for a High-Resolution Version Credits: ESA Piton de la Fournaise is also known as Reunion and is a twin shield volcano located in the western part of the Indian Ocean. The island of Reunion is made up of two volcanic mountains, Piton des Neiges which covers the central part of the island and Piton de la Fouranaise that is located on the eastern part of the island. These twin summits have been highly eroded over time. Sunrise at Piton de la Fournaise in full eruption and lava flows down to the Indian Ocean. Piton de la Fournaise in full eruption. Over time there has been two catastrophic eruptions, the first resulting in a nested caldera. Within this caldera formed a cone called Moyen which suffered a similar fate and left a circular caldera measuring 4.3 miles (7 km) in diameter. Dolomieu crater showing Aa lava. Today a twin volcano primarily built up of lava is located in the western portion of the caldera. Many parasitic cones exist within the two calderas. The summit of Piton de la Fouranaise in 1961 consisted of three craters Bory, Velain, and Dolomieu. As shown in the pictures above and below Dolomieu continued to be active in an August 1986 eruption. Dual vent eruption within Dolomieu and showing lava braiding down to the Indian Ocean. Dolomieu crater with Pahoehoe lava in foreground. More images of Reunion Island. Sources of Information: Neumann van Padang M., 1963, Arabia and the Indian Ocean. Catalog of Active Volcanoes of the World, Rome: IAVCEI, 16, p.39-41. Dr. R. B. Trombley, Southwest Volcano Research Centre, Phoenix, AZ Global Volcanism Program, SI/USGS.

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