Kikai Caldera (鬼界カルデラ, Kikai karudera) (alternatively Kikaiga-shima, Kikai Caldera Complex) is a massive, mostly submerged caldera up to 19 kilometres (12 mi) in diameter in the Ōsumi Islands of Kagoshima Prefecture, Japan.[2]

Kikai Caldera
Highest point
Peak	Mount Iō (Iōjima), Iōjima, Ōsumi Islands, Japan
Elevation	704 m (2,310 ft)
Coordinates	30°47′N 130°19′E[1]
Dimensions
Length	17 km (11 mi) NS
Width	20 km (12 mi) EW
Naming
Native name	鬼界カルデラ (Japanese)
Geography
Country	Japan
State	Kagoshima Prefecture
Region	Ōsumi Islands
District	Kagoshima District
Subdivisions	Mount Yahazu, Mount Iō (Iōjima), Mount Inamura (Iōjima), Iōjima, Shin Iōjima, Takeshima, Mount Nakasone, Mount Asase, Mount Shitakisone, Iō Tai and Takeshima Tai
Municipality	Mishima
Geology
Age of rock	6,300 to 95,000 years ago

Geology

Caldera formation has been dated from about 95,000 years ago and has involved rhyolite, basalt, and andesite phases.[2] The Kikai Caldera Complex has twin ovoid caldera 20 km (12 mi) by 17 km (11 mi) in diameter.[2] Yahazu-dake (north west part of Satsuma Io-jima) and Takeshima, located on the caldera rim, are pre-caldera volcanoes.[2]

Kikai-Tozurahara eruption

This was about 95,000 years before the present and erupted Kikai-Tozurahara (K-Tz) tephra.[3] Various dating techniques give ages between 70,000 to 100,000 years before present.[4] This was distributed all over Japan but did not reach South Korea.[4]

Akahoya eruption

The caldera was the source of the Akahoya eruption, one of the largest eruptions during the Holocene (10,000 years ago to present) that produced the Kikai-Akahoya (K-Ah) tephra.[5] Between 7,200 to 7,300 years ago,[5][4][3] pyroclastic flows producing Koya ignimbrite from that eruption reached the coast of southern Kyūshū up to 100 km (62 mi) away, and ash fell as far as Hokkaidō. The eruption produced about 150 km³ of tephra,[6] giving it a Volcanic Explosivity Index of 7[7] and making it one of the most explosive in the last 10,000 years, ranking alongside the eruptions of Santorini, Paektu, Crater Lake, Kurile Lake, Samalas and Tambora.[8] According to ice cores, initially it was thought that the Akahoya eruption may have occurred in 4350 BC,[9] however this timing has later been adjusted to about 1000 years earlier.[5][3]

The eruption had a major impact on the Jōmon culture in southern Kyūshū although the impact was not as great as some commentary had suggested with Nishinozono sub-type pottery tradition, that had started prior to the eruption, maintained in Kyūshū.[10]

Eruptive history since Akahoya eruption

Kikai is still an active volcano. Io-dake(Mount Iō), Inamura-dake (south coast of Satsuma-Io-jima), Tokara-Iwo-Jima (north east coast of Satsuma-Io-jima) and Shōwa Iōjima (Shin-Io-jima) are post-caldera volcanoes within it.[2] Minor eruptions occur frequently on Mount Iō, one of the post-caldera subaerial volcanic peaks on Iōjima. Iōjima is one of three volcanic islands, two of which lie on the caldera rim. On June 4, 2013, weak tremors were recorded. Shortly after, eruptions began and continued off-and-on for several hours.[11]

Eruptions occurred: [2][12]

• old Iwo-dake stage (stage OIo-I-II)
  • phreatomagmatic eruptions and pumice fallout (stage OIo-I), followed by rhyolitic lava with continuous tephra, resulting in a volcanic edifice (stage OIo-II)
  • 3250 BCE ± 75 years (uncalibrated) Old Iwo-dake
    • OIo1a,b tephras[6]
  • 2450 BCE ± 840 years (tephrochronology) Old Iwo-dake
    • OIo2a,b tephras[6]
• Inamura-dake stage (stage In-I-IV)
  • basaltic lava flows and scoria-cone building (stage In-I-II), then phreatomagmatic eruptions (stage In-III), and then andesitic lava (stage In-IV)
  • 1830 BCE ± 75 years (uncalibrated) Inamura-dake[6]
    • In-I tephra
  • 1090 BCE ± 100 years (uncalibrated) Inamura-dake[6]
• young Iwo-dake stage (stage YIo-I-IV)
  • continuing with a different magma source including rhyolitic lava and intermittent pumice
  • 280 BCE ± 75 years (uncalibrated) Iwo-dake[6]
  • 390 ± 100 years (uncalibrated) Iwo-dake[6]
  • 750 (tephrochronology) Iwo-dake[6]
  • 830 ± 40 years (uncalibrated) Iwo-dake[6]
    • K-Iw-P1 tephra
  • 1010 ± 40 years (uncalibrated) Iwo-dake[6]
    • K-Sk-u-3 tephra
  • 1030 ± 40 years (uncalibrated) Iwo-dake[6]
    • K-Sk-u-4 tephra
  • 1340 ± 30 years (uncalibrated) Iwo-dake[6]
    • K-Iw-P2 tephra
  • 1430 ± 75 years (uncalibrated) Iwo-dake[6]
  • 13 Feb 1914 Tokara-Iwo-Jima[6]
  • Sep-Nov 1934
    • Submarine eruption with pumice
  • 7 Dec 1934 -Mar 1935 2 km east of Tokara-Iwo-Jima[2]
    • New island Shōwa Iōjima (Shin-Io-jima) with lava finally stabilised 19 January 1935
  • 1997-2003 Iwo-dake[2]
    • Formation and enlargement of new pit crater inside the summit crater
  • Apr-Nov 1998 Iwo-dake[2]
    • Ash
  • May-Aug 1999 Iwo-dake[2]
    • Ash
  • Jan, Mar, Oct-Dec 2000 Iwo-dake[2]
    • Ash
  • Feb, Apr-Dec 2001 Iwo-dake[2]
    • Ash
  • May-Jul 2002 Iwo-dake[2]
    • Ash
  • Feb, Apr-Oct 2003 Iwo-dake[2]
    • Ash
  • May-Apr, Jun, Aug-Oct 2004 Iwo-dake[2]
    • Ash
  • 3-5 May, 3-5 Jun 2013 Iwo-dake[2]
    • Minor eruptions
  • 2 Nov 2019 Iwo-dake[2]
    • Minor eruption
  • 29 Apr 2020 Iwo-dake[2]
    • Minor eruption
  • 6 Oct 2020 Iwo-dake[2]
    • Minor eruption

See also

• List of volcanoes in Japan

Further reading

• Machida, Hiroshi; Sugiyama, Shinji (2002). "The impact of the Kikai-Akahoya explosive eruptions on human societies". In Grattan, John; Torrence Robin (eds.). Natural Disasters and Cultural Change. London: Routledge. pp. 313–346. ISBN 0-415-21696-6. but also for more recent corrections to this Junzo, Uchiyama (2021). "After a Super Volcanic Eruption: a new project on social-ecological impacts of the Kikai-Akahoya disaster, 7,300 years ago". Retrieved 2022-09-18.

References

• "Kikai". Global Volcanism Program. Smithsonian Institution.
• "KIKAI Caldera". Quaternary Volcanoes in Japan. Geological Survey of Japan, AIST. 2006. Archived from the original on 2012-12-19. Retrieved 2009-01-08.
• VolcanoWorld – Kikai, Kyūshū, Japan
• 鬼界カルデラ Kikai Caldera 独立行政法人 産業技術総合研究所 地 質 調 査 総 合 セ ン タ ー
• Kikai Caldera – Volcano Photos

External links

• Satsuma-iojima - Geological Survey of Japan
• Kikai - Geological Survey of Japan
• Geology and eruptive history of Kikai Caldera - Earthquake Research Institute,The University of Tokyo
• Kikai: Global Volcanism Program- Smithsonian Institution

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На других языках

[es] Volcán Kikai

[fr] Caldeira de Kikai