The Ring of Fire (also known as the Pacific Ring of Fire, the Rim of Fire, the Girdle of Fire or the Circum-Pacific belt) is a tectonic belt of earthquakes and volcanoes. It is about 40,000 km (25,000 mi) long and up to about 500 km (310 mi) wide, and surrounds most of the Pacific Ocean. The Ring of Fire contains between 750 and 915 active or dormant volcanoes, around two-thirds of the world total. The exact number of volcanoes within the Ring of Fire depends on which regions are included. About 90% of the world's earthquakes, including most of its largest, occur within the belt. The Ring of Fire is not a single geological structure. It was created by the subduction of different tectonic plates at convergent boundaries around the Pacific Ocean. These include the Antarctic, Nazca and Cocos plates subducting beneath the South American plate; the Pacific and Juan de Fuca plates beneath the North American plate; the Philippine plate beneath the Eurasian plate; and a complex boundary between the Pacific and Australian plate. The interactions at these plate boundaries have formed oceanic trenches, volcanic arcs, back-arc basins and volcanic belts. The inclusion of some areas in the Ring of Fire, such as the Antarctic Peninsula and western Indonesia, is disputed. The Ring of Fire has existed for more than 35 million years. However, subduction has existed for much longer in some parts of the Ring; many older extinct volcanoes are located within the Ring. More than 350 of the Ring of Fire's volcanoes have been active in historical times, while the four largest volcanic eruptions on Earth in the Holocene epoch all occurred at volcanoes in the Ring of Fire. Most of Earth's active volcanoes with summits above sea level are located in the Ring of Fire. Many of these subaerial volcanoes are stratovolcanoes (e.g. Mount St. Helens), formed by explosive eruptions of tephra alternating with effusive eruptions of lava flows. Lavas at the Ring of Fire's stratovolcanoes are mainly andesite and basaltic andesite but dacite, rhyolite, basalt and some other rarer types also occur. Other types of volcano are also found in the Ring of Fire, such as subaerial shield volcanoes (e.g. Plosky Tolbachik), and submarine seamounts (e.g. Monowai).
History From Ancient Greek and Roman times until the late 18th century, volcanoes were associated with fire, based on the ancient belief that volcanoes were caused by fires burning within the Earth. This historical link between volcanoes and fire is preserved in the name of the Ring of Fire, despite the fact that volcanoes do not burn the Earth with fire. The existence of an orogenic belt of volcanic activity around the Pacific Ocean was known in the early 19th century; for example, in 1825 the pioneering volcanologist G. P. Scrope described the chains of volcanoes around the Pacific Ocean's rim in his book Considerations on Volcanos [sic]. Three decades later, a book about the Perry Expedition to Japan commented on the Ring of Fire volcanoes as follows: "They [the Japanese Islands] are in the line of that immense circle of volcanic development which surrounds the shores of the Pacific from Tierra del Fuego around to the Moluccas." (Narrative of the Expedition of an American Squadron to the China Seas and Japan, 1852–54.) An article appeared in Scientific American in 1878 outlined the phenomenon of volcanic activity around the boundaries of the Pacific. Early explicit references to volcanoes forming a "ring of fire" around the Pacific Ocean also include Alexander P. Livingstone's book Complete Story of San Francisco's Terrible Calamity of Earthquake and Fire, published in 1906, in which he describes "... the great ring of fire which circles round the whole surface of the Pacific Ocean.". In 1912, geologist Patrick Marshall introduced the term "Andesite Line" to mark a boundary between islands in the southwest Pacific, which differ in volcano structure and lava types. The concept was later extended to other parts of the Pacific Ocean. The Andesite Line and the Ring of Fire closely match in terms of location. The development of the theory of plate tectonics since the early 1960s has provided the current understanding and explanation of the global distribution of volcanoes and earthquakes, including those in the Ring of Fire.
Geographic boundaries There is consensus among geologists about most of the regions which are included in the Ring of Fire. There are, however, a few regions on which there is no universal agreement. (See § Distribution of volcanoes). Indonesia lies at the intersection of the Ring of Fire and the Alpide belt (which is the Earth's other very long subduction-related volcanic and earthquake zone, also known as the Mediterranean–Indonesian volcanic belt, running east–west through southern Asia and southern Europe). Some geologists include all of Indonesia in the Ring of Fire; many geologists exclude Indonesia's western islands (which they include in the Alpide belt). Some geologists include the Antarctic Peninsula and the South Shetland Islands in the Ring of Fire, other geologists exclude these areas. The rest of Antarctica is excluded because the volcanism there is not related to subduction. The Ring of Fire does not extend across the southern Pacific Ocean from New Zealand to the Antarctic Peninsula or from New Zealand to the southern tip of South America because the submarine plate boundaries in this part of the Pacific Ocean (the Pacific–Antarctic Ridge, the East Pacific Rise and the Chile Ridge) are divergent instead of convergent. Although some volcanism occurs in this region, it is not related to subduction. Some geologists include the Izu Islands, the Bonin Islands, and the Mariana Islands, other geologists exclude them.
Land areas
Volcanoes in the central parts of the Pacific Basin, for example the Hawaiian Islands, are very far from subduction zones and they are not part of the Ring of Fire.
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