Island arc - wikipedia Island arc This article is about the geographic feature. For the scientific journal, see Island Arc ( journal ). This article does not cite any sources. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. ( October 2009 ) The Ryukyu Islands form an island arc. An island arc is a type of archipelago, often composed of a chain of volcanoes, with arc - shaped alignment, situated parallel and close to a boundary between two converging tectonic plates. Most of these island arcs are formed as one oceanic tectonic plate subducts another one and, in most cases, produces magma at depths below the over-riding plate. However, this is only true for those island arcs that are part of the group of mountain belts which are called volcanic arcs, a term which is used when all the elements of the arc - shaped mountain belt are composed of volcanoes. For example, large parts of the Andes - Central American - Canadian mountain chain may be known as a volcanic arc, but they are not islands ( being situated upon and along a continental area ) and are thus not classified as an island arc. On the other hand, the Aegean or Hellenic arc in the Mediterranean area, composed of numerous islands such as Crete, is an island arc, but is not volcanic. Parallel to it is the South Aegean Volcanic Arc, which is the volcanic island arc of the same tectonic system. Contents 1 Classification 2 Tectonic formation 3 Examples 3.1 Ancient island arcs 4 See also Classification There is some debate about the usefulness of the distinction between island arcs and volcanic arcs. The term `` volcanic island arc '' is merely a sub-classification of `` island arc. '' Island arcs are tectonically created arc - shaped mountain belts that are partly below sea level. Essentially, they represent a specific geographic - topographic situation in which a mountain belt is partly submerged in ocean. Many of these are composed of volcanoes, and can thus be further classified as volcanic island arcs. Tectonic formation See also : Subduction In the subduction zone, the addition of volatiles such as water induces partial melting of the oceanic crust because the volatiles ( such as water ) boil faster than the surrounding rock, forcing the rock apart. This process, called flux melting, generates low - density calc - alkaline magma that buoyantly rises to intrude and be extruded through the lithosphere of the overriding plate. The resulting volcano chain has the shape of an arc parallel to the convergent plate boundary and convex toward the subducting plate. One of the theories to explain the arc shape views this as a consequence of the geometry of the spherical plate crumpling along a line on a spherical surface, but only the more broadly shaped arcs can be explained in this way. On the subducting side of the island arc is a deep and narrow oceanic trench, which is the trace at the Earth 's surface of the boundary between the downgoing and overriding plates. This trench is created by the gravitational pull of the relatively dense subducting plate pulling the leading edge of the plate downward. Multiple earthquakes occur along this subduction boundary with the seismic hypocenters located at increasing depth under the island arc : these quakes define the Wadati -- Benioff zones. Ocean basins that are being reduced by subduction are called ' remnant oceans ' as they will slowly be shrunken out of existence and crushed in the subsequent orogenic collision. This process has happened repeatedly in the geological history of the Earth. Examples Island arc Country Trench Basin or marginal sea Overriding Plate Subducting plate Aleutian Islands United States Aleutian Trench Bering Sea North American Plate Pacific Plate Kuril Islands Russia Kuril -- Kamchatka Trench Sea of Okhotsk North American Plate Pacific Plate Japanese Archipelago Japan Japan Trench 、 Nankai Trough Sea of Japan North American Plate, Eurasian Plate Pacific Plate, Philippine Sea Plate Ryukyu Islands Japan Ryukyu Trench East China Sea ( Okinawa Trough ) Eurasian Plate Philippine Sea Plate Philippine Islands Philippines Philippine Trench South China Sea, Celebes Sea Eurasian Plate Philippine Sea Plate Sunda Islands Indonesia Java Trench Java Sea, Flores Sea Eurasian Plate Australian Plate Andaman and Nicobar Islands India Northern Java Trench Andaman Sea Eurasian Plate Indo - Australian Plate Izu Islands and Bonin Islands ( Ogasawara Islands ) Japan Izu - Ogasawara Trench Philippine Sea Plate Pacific Plate Mariana Islands United States Mariana Trench Philippine Sea Plate Pacific Plate Bismarck Archipelago Papua New Guinea New Britain Trench Pacific Plate Australian Plate Solomon Islands ( archipelago ) Solomon Islands San Cristobal Trench Pacific Plate Australian Plate New Hebrides Vanuatu New Hebrides Trench Pacific Plate Australian Plate Tonga islands Tonga Tonga Trench Australian Plate Pacific Plate Antilles Puerto Rico Trench Caribbean Sea Caribbean Plate North American Plate, South American Plate South Sandwich Islands United Kingdom South Sandwich Trench Scotia Sea Scotia Plate South American Plate Aegean or Hellenic arc Greece Eastern Mediterranean Trench Aegean Sea Aegean Sea Plate or Hellenic Plate African Plate South Aegean Volcanic Arc Greece Eastern Mediterranean Trench Aegean Sea Aegean Sea Plate or Hellenic Plate African Plate Ancient island arcs Insular Islands Intermontane Islands See also Islands portal Back - arc basin High island Volcanic arc Retrieved from `` https://en.wikipedia.org/w/index.php?title=Island_arc&oldid=818645251 '' Categories : Archipelagoes Plate tectonics Coastal and oceanic landforms Island arcs Hidden categories : Articles lacking sources from October 2009 All articles lacking sources All articles with unsourced statements Articles with unsourced statements from December 2010 Talk Contents About Wikipedia Afrikaans Asturianu भोजपुरी Català Čeština Deutsch Eesti Ελληνικά Español فارسی Français Gaeilge 한국어 Հայերեն हिन्दी Bahasa Indonesia עברית Limburgs Nederlands 日本 語 Oʻzbekcha / ўзбекча Polski Português Русский Slovenčina Slovenščina Svenska తెలుగు ไทย Türkçe Українська 中文 24 more Edit links This page was last edited on 4 January 2018, at 19 : 26. 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Question: geographically speaking where might one generally find island arcs
Answer: close to a boundary between two converging tectonic plates