Kagoshima graben
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Kagoshima graben | |
|---|---|
  30km 19miles Ō s u m i i s l a n d s I n n e r a n d O u t e r K i k a i C a l d e r a A t a S o u t h C a l d e r a A t a N o r t h C a l d e r a A r i a C a l d e r a K a k u t o C a l d e r a K o b a y a s h i C a l d e r a Map showing Kagoshima graben (red) and its caldera
(violet) with active volcanoes within graben as symbols[1] | |
| Coordinates: 31°24′N 130°42′E / 31.4°N 130.7°E / 31.4; 130.7 | |
| Volcanic zone | Kagoshima graben |
| Last eruption | 2026 |
The Kagoshima graben is a large and complex volcano-tectonic graben located on the island of Kyushu in southern Japan and under the northeast East China Sea.[1] It is associated with the subduction of the Philippine Sea plate beneath the Eurasia plate and contains volcanic caldera responsible for some of the largest eruptions in the Holocene and the most currently active volcano in Japan, Sakurajima.
It was not until 1986 that the analogy of a volcano-tectonic graben was raised in the geological literature between the Kagoshima graben and similar structures like the Taupō Rift in New Zealand and Lake Toba in Indonesia which also contain Quaternary caldera.[2] The Kagoshima graben is at the northeast end of the Ryukyu Arc of volcanoes and is related to the tectonics that created the Okinawa Trough which is a back-arc basin.[2]
The island chain that is today's Japan has been twisted during the collision of at least three tectonic plates over the last 20 million years. As a result in the southern region of Ksushu below the southwest Japan arc of volcanoes seen on Honshu, the major geological structures have been distorted into bends. The southern half of Kyushu island consists of stacked thrust sheets composed predominantly of Jurassic to Palaeogene clastic rocks.[3] The Kagoshima graben is a much younger geological structure at the far south of Ksushu and accordingly has to its north the geological formations of the Hitoyoshi Bend, to its northwest the Hokusatsu Bend and to its northeast the formations of the Nojiri Bend.[4]
The Ryukyu Arc has been formed by the subduction of the Philippine Sea plate beneath the Eurasia plate.[2] At the Kagoshima graben the direction of relative convergence is about N45°W and its rate is between 4 and 5 cm/year (1.6 and 2.0 in/year).[3] The complexity increases as the Philippine Sea plate is here subducting under the smaller Okinawa plate which is colliding with the Amur plate portion of the Eurasia plate. The larger Pacific plate is subducting under both of these. Crustal extension started at about 13 million years ago at the southern end of Kyushu and has with northwards migration since reached the middle part of Kyushu at the level of Beppu Bay, where it is still active today.[3] At its northern end is the Kagoshima graben whose downfaulting started about 2.9 million years ago after the late Pliocene.[5]
With regard to the major tectonic faults, in the northern Ryukyu Arc the Amami-Kagoshima Tectonic Line aligns with the southern aspects of the Kagoshima graben. The Kyushu portion of the Median Tectonic Line commences to the northwest of the Kagoshima graben and the Nobeoka Tectonic Line, a regional thrust, commences on the eastern aspect of the Kagoshima Bay and runs to the northeast of the graben.[3]
Eruptions
Holocene active volcanoes include Sakurajima, the most currently active in Japan, Shinmoedake Takachiho-no-mine, Mount Kaimon, Mount Iō (Iōjima) and Inamura-dake. The Kamo volcanic field had two late Holocene eruptions.[6] Please see the respective articles for these volcanoes eruption history.
The major caldera formed by large eruptions are younger than 600,000 years, and are from south to north Kikai Caldera, Ata South Caldera, Ata North Caldera, Aira Caldera, and at its northern end the Kakuto and Kobayashi caldera,[1] which are sometimes combined as the Kakuto volcanic centre.[7] The Kakuto caldera formed in an eruption about 330,000 years ago and has been infilled since with many eruptions from subsequent stratovolcanoes.[7] Sub-caldera with notable holocene eruptions include the Wakamiko sub-caldera of Aira caldera and the Ikeda sub-caldera of Ata South Caldera.[1] Tephras from these largest eruptions have been found up to 600 km (370 mi) to the north in Japan as southwesterly winds dominate.[8]
| Start Date | Years before 1950 (BP) | VEI[9] | DRE volume (km3) |
Tephra volume (km3) |
Comment |
|---|---|---|---|---|---|
| 1471 November 3, 1471 | 479 | 5 | 0.53[1] | 0.49[1] | Aira caldera. Explosive (P3 tephra) with effusive eruption of Bunmei lava possibly less than VEI 5 ending on or after October 8, 1476.[10][1] |
| 2690 740 ± 75 BCE | 26902690 ± 75 | 5 | 5[11] | - | Ikeda sub-caldera of Ata South Caldera, Tephra layer Ikp[12] |
| 7300 5350 BCE | 73007300 | 7 | 500 | - | Akahoya eruption of Kikai caldera.[13] Produced Koya (Take-shima) pyroclastic flow (K-Ky).[14] |
| 8050 6100 ± 1000 BCE | 8050 8050 ± 1000 | 6 | - | 12 | Wakamiko sub-caldera of Aira caldera |
| 29788 27838 ± 300 BCE | 29788 29788 ± 300 | 7 | 800 | 400[15] | Aira caldera, AT tephra,[8] Osumi pumice |
| 95000 93050 BCE | 95000 95000 | 6 | 130 | - | Tozurahama eruption of Kikai caldera.[13] Produced Nagase ignimbrite (K-Ns)[14] |
| 140000 138050 BCE | 140000 140000 | 6 | 130 | - | Koabi eruption of Kikai caldera[13] Produced Koabi ignimbrite (K-ab).[14] |
References
- 1 2 3 4 5 6 7 Nishihara, A.; Geshi, N.; Naruo, H. (2022). "Long-term change of the eruption activities of Sakurajima volcano, Japan, inferred from the fallout tephra deposits". Frontiers in Earth Science. 10. 988373. Bibcode:2022FrEaS..10.8373N. doi:10.3389/feart.2022.988373.
- 1 2 3 Yokoyama, I.; Ohkawa, S. (1986). "The subsurface structure of the Aira caldera and its vicinity in southern Kyushu, Japan". Journal of volcanology and geothermal research. 30 (3–4): 253–282. Bibcode:1986JVGR...30..253Y. doi:10.1016/0377-0273(86)90057-0.
- 1 2 3 4 Fabbri, O.; Monié, P.; Fournier, M. (2004). "Transtensional deformation at the junction between the Okinawa trough back-arc basin and the SW Japan island arc". In Grocott, J.; McCaffrey, K. J. W.; Taylor, G.; Tikoff, B. (eds.). Vertical Coupling and Decoupling in the Lithosphere. Vol. 227. London: Geological Society. p. 297–312. ISBN 978-1862391598.
- ↑ Murata, A. (1987). "Hokusatsu bend and clockwise rotation of the southwest Japan arc". Journal of the Faculty of Science, University of Tokyo. 21 (4): 333–349.
- ↑ H., Kamata; Kodama, K. (1994). "Tectonics of an arc-arc junction: an example from Kyushu Island at the junction of the Southwest Japan Arc and the Ryukyu Arc". Tectonophysics. 233 (1–2): 69–81. Bibcode:1994Tectp.233...69K. doi:10.1016/0040-1951(94)90220-8.
- ↑ Nche, LA; Hasegawa, T; Aka, FT; Kobayashi, T; Németh, K; Asaah, AN; Kaneda, Y; Nishihara, A; Bate-Tibang, EE; Lebga, AK; Tiabou, AF (2021). "Lithostratigraphy and geochemistry of Aojiki volcano and Sumiyoshiike and Yonemaru maars, Kamo Volcanic Field (Southern Kyushu), Japan". Journal of Volcanology and Geothermal Research. 412 (107170). doi:10.1016/j.jvolgeores.2020.107170.
- 1 2 Moriwaki, H.; Nakamura, N.; Nagasako, T.; Lowe, D. J.; Sangawa, T. (2016). "The role of tephras in developing a high-precision chronostratigraphy for palaeoenvironmental reconstruction and archaeology in southern Kyushu, Japan, since 30,000 cal. BP: an integration". Quaternary International. 397: 79–92. Bibcode:2016QuInt.397...79M. doi:10.1016/j.quaint.2015.05.069.
- 1 2 Smith, V.C.; Staff, R.A.; Blockley, S.P.E.; Ramsey, C.B.; Nakagawa, T.; Mark, D.F.; Takemura, K.; Danhara, T. (1 May 2013). "Identification and correlation of visible tephras in the Lake Suigetsu SG06 sedimentary archive, Japan: chronostratigraphic markers for synchronising of east Asian/west Pacific palaeoclimatic records across the last 150 ka". Quaternary Science Reviews. 67: 121–137. doi:10.1016/j.quascirev.2013.01.026.
- ↑ Venzke, E. (31 March 2026). "[Database] Volcanoes of the World (v. 5.3.5; 31 Mar 2026)". Global Volcanism Program distributed by Smithsonian Institution. doi:10.5479/si.GVP.VOTW5-2025.5.3.
- ↑ "Aria". Global Volcanism Program. Smithsonian Institution. Retrieved 29 March 2026.
- ↑ "IAVCEI 2013 Scientific Assembly A Guide for Mid-Conference Field Trip". Retrieved 2022-09-19.
- ↑ Inakura, Hirohito; Naruo, Hideto; Okuno, Mitsuru; Kobayashi, Tetsuo (2014). "Eruptive History of Ikeda Volcano, Ibusuki Area, Southern Kyushu, Japan". Bulletin of the Volcanological Society of Japan. 59 (4): 255–268. doi:10.18940/kazan.59.4_255. ISSN 0453-4360.
- 1 2 3 Tatsumi, Y.; Suzuki-Kamata, K.; Matsuno, T.; Ichihara, H.; Seama, N.; Kiyosugi, K.; Nakaoka, R.; Nakahigashi, K.; Takizawa, H.; Hayashi, K.; Chiba, T.; Shimizu, S.; Sano, M.; Iwamaru, H.; Morozumi, H.; Sugioka, H.; Yamamoto, Y. (2018). "Giant rhyolite lava dome formation after 7.3 ka supereruption at Kikai caldera, SW Japan". Scientific Reports. 8. 2793. doi:10.1038/s41598-018-21066-w.
- 1 2 3 "Geology and eruptive history of Kikai Caldera". Tokyo: University of Tokyo. Retrieved 4 April 2026.
- ↑ Tsutsui, T.; Miki, D.; Iguchi, M. (2024). "Seabed benchmark system in Aira Caldera". Earth, Planets and Space. 76. 99. doi:10.1186/s40623-024-02044-1.