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Sakurajima

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Sakurajima
Sakurajima55.jpg
View of Sakurajima from mainland Kagoshima, 2009
Highest point
Elevation 1,117 m (3,665 ft)
Coordinates 31°34′50″N 130°39′29″E / 31.58056°N 130.65806°E / 31.58056; 130.65806Coordinates: 31°34′50″N 130°39′29″E / 31.58056°N 130.65806°E / 31.58056; 130.65806
Geography
Sakurajima is located in Japan
Sakurajima
Sakurajima
Geology
Mountain type composite volcano
Last eruption 1955 to 2018 (Ongoing)[1]

Sakurajima (Japanese: 桜島, literally "Cherry blossom Island") is an active composite volcano and a former island in Kagoshima Prefecture in Kyushu, Japan.[2] The lava flows of the 1914 eruption connected it with the Osumi Peninsula.[3] It is the most active volcano in Japan.[4]

The volcanic activity still continues, dropping volcanic ash on the surroundings. Earlier eruptions built the white sand highlands in the region. The most recent eruption started on May 2, 2017. On September 13, 2016 a team of experts from Bristol University and the Sakurajima Volcano Research Centre in Japan suggested that the volcano could have a major eruption within 30 years.[5]

Sakurajima is a stratovolcano. Its summit has three peaks, Kita-dake (northern peak), Naka-dake (central peak) and Minami-dake (southern peak) which is active now.

Kita-dake is Sakurajima's highest peak, rising to 1,117 m (3,665 ft) above sea level. The mountain is in a part of Kagoshima Bay known as Kinkō-wan. The former island is part of the city of Kagoshima.[6] The surface of this volcanic peninsula is about 77 km2 (30 sq mi).

History

Geological history

A map of Sakurajima in 1902, showing it as a distinct island.

Sakurajima is in the 25 km (15 mi)-wide Aira caldera, which formed in an enormous "blow-out-and-cave-in" eruption 22,000 years ago.[7] 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 km (12 mi) across. Tephra fell as far as 1,000 km (620 mi) 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.[8] It lies about 8 km (5 mi) south of the centre of the caldera. Its first eruption in recorded history occurred in 963 AD.[9] Most of its eruptions are strombolian,[9] affecting only the summit areas, but larger plinian eruptions have occurred in 1471–1476, 1779–1782 and 1914.[10]

Volcanic activity at Kita-dake ended around 4,900 years ago: later eruptions have been centered on Minami-dake.[11] Since 2006, activity has centred on Showa crater, to the east of the summit of Minami-dake.[12]

1914 eruption

Date January 1914
Type Peléan
VEI 4
Impact Pre-eruption earthquakes killed at least 35 people and an additional 23 people died[13]; caused an evacuation and significant changes to the local topography.
A torii in Kurokami-cho, Kagoshima is half-buried by ash and stones caused by the 1914 eruption.

The 1914 eruption began on January 11. It was the most powerful in twentieth-century Japan. The volcano had been dormant for over a century until 1914.[7] Almost all residents had left the island in the previous days, in response to several large earthquakes that warned them that an eruption was imminent. Initially, the eruption was very explosive, generating eruption columns and pyroclastic flows, but after a very large earthquake on January 13, 1914 which killed 35 people, it became effusive, generating a large lava flow.[7] Lava flows filled the narrow strait between the island and the mainland, turning it into a peninsula. Lava flows are rare in Japan—the high silica content of the magmas there mean that explosive eruptions are far more common[14]—but the lava flows at Sakurajima continued for months.[7] The island grew, engulfing several smaller islands nearby, and eventually becoming connected to the mainland by a narrow isthmus. Parts of Kagoshima bay became significantly shallower, and tides were affected, becoming higher as a result.[7]

During the final stages of the eruption, the centre of the Aira Caldera sank by about 60 cm (24 in), due to subsidence caused by the emptying out of the underlying magma chamber.[7] The subsidence occurring at the centre of the caldera rather than directly underneath Sakurajima showed that the volcano draws its magma from the same reservoir that fed the ancient caldera-forming eruption.[7] The eruption partly inspired a 1914 movie, The Wrath of the Gods, centering on a family curse that ostensibly causes the eruption.

Recent activity

Topographic map
An image taken from the International Space Station showing Sakurajima and its surroundings on 10 January 2013.
Sakura-jima eruption as seen on August 18, 2013

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.[9]

Monitoring of the volcano and predictions of large eruptions are particularly important because it is 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.[15]

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.[16]

Sakurajima is part of the Kirishima-Yaku National Park, and its lava flows are a major tourist attraction. The area around Sakurajima contains several hot spring resorts. One of the main agricultural products of Sakurajima is a huge basketball-sized white radish (Sakurajima daikon).[17]

On 10 March 2009, Sakurajima erupted, sending debris up to 2 km (1.2 mi). An eruption had been expected following a series of smaller explosions over the weekend. It is not thought there was any damage caused.[18]

In 2011 and 2012, Sakurajima experienced several significant eruptions; volcanic activity continues into 2013.[19] Photographer Martin Rietze captured a rare picture of lightning within the ash plume in January 2013 during a magma ejection, which was a NASA astronomy pic of the day in March 2013.[20]

On 18 August 2013, the volcano erupted from Showa crater and produced its highest recorded plume of ash since 2006, rising 5,000 metres high and causing darkness and significant ash falls on the central part of Kagoshima city. The eruption occurred at 16:31 and was the 500th eruption of the year.[21]

In August 2015, Japan's meteorological agency issued a level 4 emergency warning, which urges residents to prepare to evacuate.[22] Scientists warned that a major eruption could soon take place at the volcano;[23] it eventually did erupt around 20:00 on 5 February 2016.[24]

After a long pause of eruptions at the vent, the eruptions abruptly stopped there and returned to the Showa crater, on April 4, 2016, some 8–9 days preceding major earthquakes on the Median Tectonic Line near Kumamoto, Japan.[25] Then, three months later, on July 26, it spewed volcanic ash 5,000 m (16,000 ft) into the air.[26]

Timeline

Comparison

In Japanese literature

Sakurajima is the title of a 1946 short story, written by the Japanese writer Haruo Umezaki, about a disillusioned Navy officer stationed on the volcano island towards the end of World War II as American air force planes bomb Japan. The story is based on Umezaki's own experience; he was stationed in a military cipher base in the nearby Prefecture city of Kagoshima.

See also

Notes

  1. ^ "Sakurajima volcano". 19 Feb 2018.
  2. ^ Nussbaum, Louis-Frédéric. (2005). "Sakurajima" in Japan Encyclopedia, p. 814; see photo, caption -- Kagoshima after Sakurashima eruption, Illustrated London News. January 1914.
  3. ^ Davison C (1916-09-21). "The Sakura-Jima Eruption of January, 1914". Nature. 98 (2447): 57–58. Bibcode:1916Natur..98...57D. doi:10.1038/098057b0.
  4. ^ "Sakurajima, Japan's Most Active Volcano". nippon.com. Nippon Communications Foundation. May 16, 2018. Retrieved August 2, 2018.
  5. ^ McCurry, Justin (13 September 2016). "New data points to major eruption of Japanese volcano". the Guardian. Retrieved 17 April 2018.
  6. ^ Nussbaum, "Kagoshima prefecture" at p. 447.
  7. ^ a b c d e f g "The 1914 Sakurajima explosion at Volcanoworld". Archived from the original on 2008-06-16. Retrieved 2007-08-03.
  8. ^ "Sakurajima at Activolcan.info" (in French). Retrieved 2007-08-03.
  9. ^ a b c "Sakura-jima, Japan". VolcanoWorld. Oregon State University. Archived from the original on 2008-08-01. Retrieved 2008-10-12.
  10. ^ "Sakurajima at the Earthquake Research Institute, University of Tokyo". Archived from the original on 2008-02-14. Retrieved 2007-08-03.
  11. ^ "Sakura-jima". Global Volcanism Program. Smithsonian Institution. Retrieved 2007-08-04.
  12. ^ Iguchi, Masato (20 July 2013). "Forecasting volcanic activity of Sakurajima" (PDF). Proceedings of IAVCEI 2013 Scientific Assembly. Archived from the original (PDF) on 20 October 2013. Retrieved 18 August 2013.
  13. ^ "Japan's Sakurajima volcano due for major eruption within 30 years, say scientists". BBC News. 14 September 2016. Retrieved 24 February 2017.
  14. ^ "Japanese Volcanoes at the Northern Illinois University". Archived from the original on 2010-08-19. Retrieved 2007-08-06.
  15. ^ "Reuters report on Sakurajima explosion, June 5th 2006". Archived from the original on 2007-09-28. Retrieved 2007-08-06.
  16. ^ "Decade Volcano Sakurajima at the Earthquake Research Institute". Archived from the original on 2007-08-19. Retrieved 2007-08-06.
  17. ^ "Touristic information on synapse.ne.jp". Retrieved 2007-08-06.
  18. ^ "Japan's Sakurajima volcano erupts". March 10, 2009. Retrieved March 16, 2012.
  19. ^ "Volcanic activity world-wide 16 November 2012: Ruapehu, Paluweh, Michael, Kilauea, Fuego, Santiaguito, Nevado del Ruiz, Reventador, Sakurajima, Mammoth Mountain (Long Valley),Ambrym, Nyiragongo". www.volcanodiscovery.com. Retrieved 17 April 2018.
  20. ^ Nemiroff, R.; Bonnell, J., eds. (11 March 2013). "Sakurajima Volcano with Lightning". Astronomy Picture of the Day. NASA.
  21. ^ "Sakurajima spews its highest volcanic column ever at 5,000 meters". Asahi Shimbun. 18 August 2013. Archived from the original on 4 March 2016. Retrieved 18 August 2013.
  22. ^ "Volcano alerts issued in Ecuador, Japan". 15 August 2015. Retrieved 16 August 2015.
  23. ^ "Sakurajima in Japan Might Be Headed Towards a Large Eruption". wired.com. Retrieved 17 April 2018.
  24. ^ "Sakurajima volcano in Japan erupts". The Guardian. Associated Press. 5 February 2016. Retrieved 5 February 2016.
  25. ^ "Volcanic activity worldwide 4 Apr 2016: Popocatépetl volcano, Bromo, Turrialba, Sangay, Sakurajima,..." www.volcanodiscovery.com. Retrieved 17 April 2018.
  26. ^ "Kagoshima's Sakurajima volcano erupts, spews plume 5,000 meters up". 26 July 2016. Retrieved 17 April 2018 – via Japan Times Online.

References

  • Townley, S.D. (1915). "Seismographs at the Panama-Pacific Exposition," Bulletin of the Seismological Society of America. Stanford, California: Seismological Society of America. OCLC 1604335
  • Teikoku's Complete Atlas of Japan, Teikoku-Shoin Co., Ltd. Tokyo 1990

Further reading

  • Aramaki S. (1984), Formation of the Aira Caldera, Southern Kyūshū, ~22,000 years ago, Journal of Geophysical Research, v. 89, issue B10, p. 8485.
  • Guide-books of the Excursions: Pan-Pacific Science Congress, 1926, Japan. Tokyo: Tokyo Printing Co. OCLC 7028702
  • Johnson, H & Kuwahara, S (2016), Sakurajima: Maintaining an island essence, Shima: The International Journal of Research into Island Cultures, vol. 10, no.1, pp. 48–66.

External links

  • Sakurajima: National catalogue of the active volcanoes in Japan - Japan Meteorological Agency
  • Aira (Sakurajima) - Smithsonian Institution: Global Volcanism Program
  • Sakurajima Volcano Research Center - Kyoto University
  • Aira / Sakurajima, Global Volcanic Program
  • Footage of the March 2009 eruption - BBC
  • Schoolchildren wearing helmets to protect against stones thrown out by the nearby Sakurajima volcano (which is in background)
  • Google Earth view

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