Monday, September 7, 2009

Sakurajima Volcanic Mountain, Kagoshima

Sakurajima is an active composite volcano and a former island of the same name in Kagoshima Prefecture of Japan. The lava flows of the 1914 eruption caused the former island to be connected with the Osumi Peninsula. The volcanic activity still continues, dropping large amounts of volcanic ash on the surroundings. Earlier eruptions built the white sands highlands in the region. Sakurajima is a composite mountain. Its summit is split into three peaks, Kitadake (northern peak), Nakadake (central peak) and Minamidake (southern peak) which is active now.
Sakurajima was formed in an enormous eruption 22,000 years ago. Several hundred cubic kilometres of ash and pumice were ejected, causing the magma chamber underneath the erupting vents to collapse. The resulting caldera is over 20 kilometres across. Tephra fell as far as 1,000 kilometres from the volcano. Sakurajima is a modern active vent of the same Aira caldera volcano.
Sakurajima was formed by later activity within the caldera, beginning about 13,000 years ago. It lies about 8 kilometres south of the centre of the caldera. Its first eruption in recorded history occurred in 963 AD. Most of its eruptions are strombolian, affecting only the summit areas, but larger plinian eruptions have occurred in 1471–1476, 1779–1782 and 1914. Volcanic activity at Kitadake ended around 4,900 years ago: subsequent eruptions have been centered on Minamidake.
Sakurajima's activity became more prominent in 1955, and the volcano has been erupting almost constantly ever since. Thousands of small explosions occur each year, throwing ash to heights of up to a few kilometers above the mountain. The Sakurajima Volcano Observatory was set up in 1960 to monitor these eruptions.
Monitoring of the volcano and predictions of large eruptions are particularly important because of its location in a densely populated area, with the city of Kagoshima's 680,000 residents just a few kilometers from the volcano. The city conducts regular evacuation drills, and a number of shelters have been built where people can take refuge from falling volcanic debris. In light of the dangers it presents to nearby populations, Sakurajima was designated a Decade Volcano in 1991, identifying it as worthy of particular study as part of the United Nations' International Decade for Natural Disaster Reduction. On March 10, 2009, Sakurajima erupted, sending debris up to 2 km away. An eruption had been expected following a series of smaller explosions over the weekend. It is not thought there was any damage caused by the latest eruption. It was erupted continuously also in last end of August when I was there during my lab trip.
View of Sakurajima

Observation instruments of Volcanic activities at Sakurajima Volcano Research Center, DPRI, Kyoto University.

Seismic Stations at Sakurajima

View of Sakurajima

Office building of Sakurajima International Volcanic Sabo Center

Check dam constructed to control volcanic induced debris flows

Channel works constructed to control volcanic induced debris flows

5 comments:

  1. An informative post on the Sakurajima Volcanic Mountain of Kagoshima. The pictures are also very nice. Thanks for sharing.

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  2. Thank you. This document over Mt. Sakurajima was very informative and useful for my report. Thank you for posting this!

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  3. this has helped my school report. Thankss
    !

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  4. Thank for this report!!

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