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Novarupta (Russian: ''Вулкан Новарупта'', literally "new eruption") is a new volcano that was created in 1912, located on the Alaska Peninsula in Katmai National Park and Preserve, about southwest of Anchorage. Formed during the largest volcanic eruption of the 20th century, Novarupta released 30 times the volume of magma of the 1980 eruption of Mount St. Helens. ==Eruption of 1912== The eruption of Novarupta within the Aleutian Range began on June 6, 1912, and culminated in a series of violent eruptions from the original Novarupta volcano. Rated a 6 on the Volcanic Explosivity Index,〔 〕 the 60-hour-long eruption expelled of ash, 30 times as much as the 1980 eruption of Mount St. Helens.〔 〕〔 〕 The erupted magma of rhyolitic, dacitic, and andesitic composition〔Wood, C.A. and Kienle, J. (editors) (1990) ''Volcanoes of North America: United States and Canada'', Cambridge, Cambridge University Press, ISBN 0-521-36469-8, page 70.〕 resulted in more than of air fall tuff and approximately of pyroclastic ash-flow tuff.〔 〕 During the 20th century, only the 1991 eruption of Mt. Pinatubo in the Philippines was of a similar magnitude; Pinatubo ejected of tephra.〔 〕 At least two larger eruptions occurred in the 19th century: the 1815 eruption of Tambora ( of tephra)〔 〕 and the 1883 eruption of Indonesia's Krakatoa ( of tephra).〔 〕 Novarupta occurred about 2.5 miles from the peak of volcanic Mount Katmai and 4,000 feet below the post-eruption summit of Mount Katmai. During the eruption a large quantity of magma was removed from underneath the Mount Katmai area, resulting in the formation of a wide, funnel-shaped vent and the collapse of Mount Katmai's summit, creating a deep,〔 caldera.〔 〕 The eruption ended with the extrusion of a lava dome of rhyolite〔 that plugged the vent. The high and wide dome and the caldera it created form what is now referred to as Novarupta.〔 〕 Despite the magnitude of the eruption, no deaths directly resulted.〔〔 〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Novarupta」の詳細全文を読む スポンサード リンク
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