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28-599: The ridge contains Matthew Island and Hunter Island and extends from southern Vanuatu near the Volsmar seamount via the region of Ceva-i-Ra (Conway Reef) towards Fiji . Its length on this definition is about 550 km (340 mi) but earlier work included other parts of the Hunter Fracture Zone that are now known to be discontinuous topographically and on such historic definitions the length approached 1,000 km (620 mi) or more. The West Matthew volcano had its

56-491: A breeding population of red-tailed tropicbirds , with some 100–200 pairs estimated in 2007. Matthew Island ( French : île Matthew ) is also known as Umaenupne island in the indigenous language of Aneityum island in southern Vanuatu, the closest inhabited island. It is 0.7 square kilometres (0.27 sq mi) in area, 177-metre (581 ft) located at 22°21′S 171°21′E  /  22.350°S 171.350°E  / -22.350; 171.350 . The volcanic island

84-453: A serrated peak and is composed almost entirely of lava flows and slag. It contains a crater that is breached to the northwest. A lava flow from West Matthew makes up the northwest coast of the island. All known historical eruptions have come from West Matthew. After a highly seismically active period in the 1940s, construction of West Matthew began as submarine eruptions built up a new island. The new cone then emitted lava flows. The eruption

112-517: Is a new subduction zone, that is only 2 million years old. This subduction zone has been named the Matthew and Hunter subduction system , or Matthew and Hunter subduction zone , where previous work had considered it the southern termination of the New Hebrides subduction zone. Volcanism is much closer to the trench compared to previously well characterised subduction zones which is postulated to be due to

140-492: Is composed of andesite – dacitic lavas and numerous explosion craters dot the stratovolcano . A cone makes up the south part of the island, with its central crater filled by a lava dome. A 100 m (330 ft)-deep crater is located on the north-west side of the island. Hunter Island has been symbolically claimed by a micronation , the Federal Republic of Lostisland. Fumarolic and solfataric activity continues in

168-522: Is composed of two andesitic-to-dactic volcanic cones, East Matthew and West Matthew, separated by a rocky 200-metre-wide isthmus. The island was discovered by Captain Thomas Gilbert, of Charlotte , on 27 May 1788, who named it after the owner of his ship. At the time of the discovery, only East Matthew existed and it was described as having only one peak prior to the Second World War. East Matthew

196-452: Is the older part of the island, formed from basalt with a half-destroyed, 142 m (466 ft) high composite volcanic cone that is thought to be composed of three lava flows . There is still some volcanic activity on the island with sulphuric fumaroles rising from craters in the south-east. West Matthew formed in the late 1940s and may have had eruptions as recent as 1976. It is a roughly circular, 177 m (581 ft) high cone with

224-727: The Kadavu Islands . Currently the eastern Hunter Ridge is being pulled apart at the current triple junction between the New Hebrides Trench , the southernmost propagating tip of the Central Spreading Ridge backarc-spreading centre at the intersection of the New Hebrides Plate and Conway Reef Plate under the NFB, and the Hunter Fracture Zone. From 12 to 3 million years ago after the subduction polarity reversal likely caused by

252-555: The islands of the South Pacific Ocean , where low islands are found on the fringing reefs that surround most volcanic islands. Volcanic islands normally rise above a hotspot or subduction zone . Volcanic islands usually range in size between 1 and 104 square kilometres (0.4 and 40 sq mi). Islands above a certain size usually have fresh groundwater , while low islands often do not, so volcanic islands are more likely to be habitable. Many volcanic islands emerge from

280-597: The Fiji area. During the last 4 million years of this period, the opening of the NFB in a north–south direction, allowed northward subduction of the South Fiji Basin part of the Indo-Australian Plate under the NFB forming the initial Hunter Ridge. At 3 million years ago were events that lead to formation of the present Australian Plate and the major opening of the NFB shifted to its present-day east–west direction along

308-574: The Hunter Ridge area. The sampled lavas are less than a million years old and suggest magma generation involves contributions from adakitic , sediment and back arc-basin basalt (BABB) melt components. An analogy has been noted with the adakitic andesites on the Solander Islands in another very young subduction system related to the Puysegur Trench south of New Zealand. However the composition of

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336-577: The North Fiji Basin over the last 2 million years has rifted westward splitting the Hunter Ridge into two halves. New young subduction of the South Fiji Basin has created what has been called the Matthew and Hunter subduction zone. The various processes have resulted in unusually complex volcanic composition of the island's recent eruptives, as well as the continued seismicity assigned to the area as

364-589: The collision of the Pacific Plate Ontong Java Plateau with the Vitiaz Trench subduction zone, the NFB opened as a series of spreading centres and complex transform fault systems that formed due to clockwise rollback of the subducted Indo-Australian Plate as it then was. There was rapid extension in the NFB with clockwise rotation of the Vanuatu subduction zone and the counter clockwise rotation of

392-443: The deep abyss of the ocean, and feature rough or mountainous landscapes in their interiors and a diverse array of summit elevations. Researchers have observed that the island will often be covered by dense tropical forest. These limit settlement on the interior of many islands, forcing communities to develop along the coast. Larger islands may have rivers, resulting in flood hazards. Rivers deliver sediment downstream, which can dominate

420-598: The island has a domed shape, and some sources suggest a current height of its highest peak, Mont Favard, of 242 metres (794 ft), but others are higher. It was first surveyed by the British between 1853 and 1856 at 974 ft (297 m) 297 metres (974 ft) high which is still given in a recent English source. There has been volcanic activity since 1856 and before 1982 French aviation photographic studies were interpreted to give an approximate height of 260 m (850 ft). Other French sources are slightly higher. It

448-460: The local language of Futuna island in southern Vanuatu. The first recorded European sighting of the island was by Captain Thomas Fearn from his trading ship Hunter in 1798. It lies about 70 km (43 mi) east of Matthew Island at 22°24′S 172°5′E  /  22.400°S 172.083°E  / -22.400; 172.083 . About 0.6 square kilometres (0.23 sq mi) in area,

476-465: The most recent Hunter Ridge eruptives is more similar to that of the western Aleutians . The Australian Plate is subducting under the New Hebrides Plate to produce an active seismic zone and in concert with propagating back-arc extension, the volcanism of the ridge. The convergence becomes oblique so the eastern end of the ridge becomes part of the Hunter Fracture Zone that extends towards

504-690: The most recent eruption in 1956, still had steam admissions in 1983, having formed a new volcanic cone from below the sea surface in the last 80 years. Hunter Island last erupted in 1903. The Matthew and Hunter islands have unusual high-Mg andesitic to dacitic and boninite lavas. These unusual lavas have also been found from a number of seamounts at the southern regions of the Vanuatu subduction zone. Historic classifications have included mid-ocean ridge basalts (MORB) and enriched mid-ocean ridge basalts (E-MORB). Igneous rocks with primitive to evolved compositions including calc-alkaline , arc tholeiites and low-Ti island arc tholeiites have also been dredged from

532-513: The north of the island, as well as on the northeast and southeast coasts. Two small eruptions took place in the mid-1800s. In 1835, a lava flow erupted and on 15 March 1841, an explosive eruption took place. In 1895, lava was seen flowing from two craters on the east side of the island. A small (VEI 0) fissure eruption took place in 1903, on the northern side of the island, and produced lava. The island has been recognised as an Important Bird Area (IBA) by BirdLife International because it supports

560-565: The north–south-oriented Central Spreading Ridge. The northward subduction of the South Fiji Basin stopped and the Hunter Fracture Zone developed as a transform fault. The propagation of the spreading center in the NFB southward has resulted in the Hunter Ridge being rifted into two parallel segments separated by a volcanically still active rift zone that has been called the Hunter Ridge Rift Zone , or Monzier Rift . Here primitive submarine lavas have erupted through thin oceanic crust in what

588-559: The opening of the North Fiji Basin in a north–south direction, allowed northward subduction of the South Fiji Basin part of the then Indo-Australian Plate under the North Fiji Basin. From about 3 million years ago the current triple junction between the New Hebrides Plate, Australian Plate and the Conway Reef Plate became established and the southernmost propagating tip of the Central Spreading Ridge backarc-spreading centre in

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616-522: The people of Aneityum part of their custom ownership, and as of 2007 were claimed by France as part of New Caledonia . Small, arid, without fresh water and not easily accessible, the islands had no interest for Britain or France during their colonisation of the Pacific in the course of the 18th and 19th centuries. France officially annexed both islands in 1929. In 1965, the United Kingdom also claimed

644-473: The shape of the coast and contribute to erosion. Tall volcanic islands are often surrounded by protective fringing or barrier reefs, creating lagoons. The unique geological and geographical characteristics of volcanic islands make them prone to many natural hazards, which are expected to worsen due to climate change . These include volcanic eruptions, earthquakes, tsunamis, landslides, and severe weather events like hurricanes or typhoons. Studies have highlighted

672-745: The south western part of the Hunter Fracture Zone . Volcanic island Geologically, a volcanic island is an island of volcanic origin. The term high island can be used to distinguish such islands from low islands , which are formed from sedimentation or the uplifting of coral reefs (which have often formed on sunken volcanos). There are a number of volcanic islands that rise no more than 1 metre (3 ft 3 in) above sea level , often classified as islets or rocks, while some low islands, such as Banaba , Henderson Island , Makatea , Nauru , and Niue , rise over 50 metres (160 ft) above sea level. The two types of islands are often found in proximity to each other, especially among

700-583: The southern arc of the South New Hebrides Trench, where the minor New Hebrides Plate is subducted by the Australian Plate . In February 2021, a 7.7 M w quake was centered in the vicinity of Matthew and Hunter. Both Matthew Island and Hunter Island are within the Hunter Ridge part of the New Hebrides Plate and this ridge was initially formed from about 7 to 3 million years ago, when

728-533: The two islands, as part of the New Hebrides . France conducted a symbolic occupation in 1975. In 1980, on its independence, Vanuatu claimed sovereignty, but made no occupation of the islands. In 1979, Météo-France set up an automatic weather station on one of the islands, and the French Navy regularly visits both of them. Hunter Island ( French : île Hunter ) is also known as "Fern or Fearn Island", or "Leka" in

756-546: The zone being an immature subduction system at a stage before classic arc subduction volcanism. Matthew Island and Hunter Island Hunter Island and Matthew Island are two small and uninhabited volcanic islands in the South Pacific, located 300 kilometres (190 mi) east of New Caledonia and south-east of Vanuatu archipelago. Hunter Island and Matthew Island, 70 km (43 mi) apart, are claimed by Vanuatu as part of Tafea Province , and considered by

784-684: Was a VEI 2. Another VEI 2 eruption from West Matthew took place in October 1954, while a very small (VEI 0) fissure eruption occurred in approximately 1956. This marks the latest confirmed activity on Matthew Island, although tremors took place near the island in 2008, 2009 and 2011. Uncertainty surrounds a report of an eruption in 1828, as well as reports of eruptions in 1966 and 1976. The island has been recognised as an Important Bird Area (IBA) by BirdLife International because it supports breeding populations of brown boobies and blue noddies . The islands are prone to earthquakes, as they are situated near

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