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The 1815 Eruption of Mount Tambora, on the island of Sumbawa in Indonesia, was one of the most powerful eruptions in recorded history and is classified as a VEI-7 event. The eruption resulted in a brief period of significant climate change that consistently led to various cases of extreme weather. Several ''climate forcings'' coincided and interacted in a systematic manner that has not been observed since, despite other large eruptions that have occurred since the early Stone Age. Although the link between the post-eruption climate changes and the Tambora event has been established by various scientists, the understanding of the processes involved is incomplete.〔(Climate Forcing )〕 The eruption reached a climax on 10 April 1815〔(Earth Observatory )〕 and was followed by between six months and three years of increased steaming and small phreatic eruptions. The eruption column lowered global temperatures, and some experts believe this led to global cooling and worldwide harvest failures, sometimes known as the Year Without a Summer.〔 == Chronology of the eruption == Mount Tambora experienced several centuries of dormancy before 1815, as the result of the gradual cooling of hydrous magma in a closed magma chamber.〔 〕 Inside the chamber at depths between , the exsolution of a high-pressure fluid magma formed during cooling and crystallisation of the magma. Overpressure of the chamber of about was generated, and the temperature ranged from 700 to 850 °C (1,300–1,600 °F).〔 In 1812, the caldera began to rumble and generated a dark cloud.〔 〕 On 5 April 1815, a huge eruption occurred, followed by thunderous detonation sounds, heard in Makassar on Sulawesi, away, Batavia (now Jakarta) on Java away, and Ternate on the Molucca Islands away. On the morning of 6 April, volcanic ash began to fall in East Java with faint detonation sounds lasting until 10 April. What was first thought to be sound of firing guns was heard on 10 April on Sumatra more than away.〔 Raffles, S. 1830: ''Memoir of the life and public services of Sir Thomas Stamford Raffles, F.R.S. &c., particularly in the government of Java 1811–1816, and of Bencoolen and its dependencies 1817–1824: with details of the commerce and resources of the eastern archipelago, and selections from his correspondence.'' London: John Murray, cited by Oppenheimer (2003). 〕 At about 7 pm on 10 April, the eruptions intensified.〔 Three columns of flame rose up and merged.〔 The whole mountain was turned into a flowing mass of "liquid fire".〔 Pumice stones of up to in diameter started to rain down around 8 pm, followed by ash at around 9–10 pm. Pyroclastic flows cascaded down the mountain to the sea on all sides of the peninsula, wiping out the village of Tambora. Loud explosions were heard until the next evening, 11 April. The ash veil had spread as far as West Java and South Sulawesi. A "nitrous" odour was noticeable in Batavia and heavy tephra-tinged rain fell, finally receding between 11 and 17 April.〔 The first explosions were heard on this Island in the evening of 5 April, they were noticed in every quarter, and continued at intervals until the following day. The noise was, in the first instance, almost universally attributed to distant cannon; so much so, that a detachment of troops were marched from Djocjocarta, in the belief that a neighbouring post was being attacked, and along the coast boats were in two instances dispatched in quest of a supposed ship in distress. The explosion is estimated to have been a VEI-7.〔 〕 An estimated of pyroclastic trachyandesite were ejected, weighing about 10000 million tonnes. This has left a caldera measuring across and deep.〔 The density of fallen ash in Makassar was 636 kg/m³.〔 〕 Before the explosion, Mount Tambora was about high,〔 one of the tallest peaks in the Indonesian archipelago. After the explosion, it measured only (about two thirds of its previous height).〔 〕 The 1815 Tambora eruption is the largest observed eruption in recorded history (see Table I, for comparison).〔〔 〕 The explosion was heard away, and ash fell at least away.〔 Pitch darkness was observed as far away as from the mountain summit for up to two days. Pyroclastic flows spread at least from the summit. Due to the eruption, Indonesia's islands were struck by tsunami waves reaching heights up to . 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「1815 eruption of Mount Tambora」の詳細全文を読む スポンサード リンク
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