Editing Kikai Caldera (section)

==Geology==
The Kikai Caldera Complex has twin ovoid caldera {{convert|20|km|abbr=on}} by {{convert|17|km|abbr=on}} in diameter.<ref name="gbank"/> Yahazu-dake (north west part of [[Iōjima (Kagoshima)|Satsuma Io-jima]]) and [[Takeshima (Kagoshima)|Takeshima]], located on the caldera rim, are pre-caldera volcanoes.<ref name="gbank"/> The pre-caldera stage of volcanic activity involved [[rhyolite]], [[basalt]], and [[andesite]] phases.<ref name="gbank" /><ref name=":2">{{Cite book |last1=小野 |first1=晃司 |url=https://ci.nii.ac.jp/ncid/BA36838038 |title=薩摩硫黄島地域の地質 |last2=曽屋 |first2=龍典 |last3=細野 |first3=武男 |date=1982 |publisher=地質調査所 |language=ja}}</ref> The earliest definitive caldera formation has been dated back to at least 140,000 years ago, resulting from the eruption of Koabiyama [[pyroclastic flow]]s.<ref name="gbank" /><ref name=":3">Nishino, Y., Takarada, S. and Geshi, N. (2019) [https://www.gsj.jp/researches/openfile/openfile2019/openfile0680.html Volcanic activities and eruption sequence of the large-scale eruption at Aira, Kikai, Ata, Kutcharo, Towada, Mashu and Ikeda Volcanoes.] Open-File Report of the Geological Survey of Japan, AIST, no.680, p. 1-126.</ref><ref name=":2" /> The formation of caldera has been associated with at least three catastrophic [[ignimbrite]] eruptions.<ref name="gbank" /><ref name=":3" /><ref name=":2" /> Additionally, there are two older deposits (Koseda pyroclastic flows and Anbo tephra) of large caldera-forming eruptions in the vicinity, although their attribution to the Kikai caldera remains controversial.<ref>{{Cite journal |last1=Ito |first1=Hisatoshi |last2=Uesawa |first2=Shimpei |last3=Nanayama |first3=Futoshi |last4=Nakagawa |first4=Shojiro |date=2017-05-15 |title=Zircon U–Pb dating using LA-ICP-MS: Quaternary tephras in Yakushima Island, Japan |url=https://linkinghub.elsevier.com/retrieve/pii/S0377027316303079 |journal=Journal of Volcanology and Geothermal Research |language=en |volume=338 |pages=92–100 |doi=10.1016/j.jvolgeores.2017.02.003|bibcode=2017JVGR..338...92I |url-access=subscription }}</ref><ref>{{Cite journal |last1=Moriwaki |first1=Hiroshi |last2=Westgate |first2=John A. |last3=Sandhu |first3=Amanjit S. |last4=Preece |first4=Shari J. |last5=Arai |first5=Fusao |date=2008-02-01 |title=New glass fission-track ages of Middle Pleistocene tephras on Yakushima Island, southern Japan |url=https://www.sciencedirect.com/science/article/pii/S1040618206002874 |journal=Quaternary International |series=Global Tephra Studies: John Westgate and Andrei Sarna-Wojcicki Commemorative Volume |language=en |volume=178 |issue=1 |pages=128–137 |doi=10.1016/j.quaint.2006.11.013 |bibcode=2008QuInt.178..128M |issn=1040-6182|url-access=subscription }}</ref><ref>{{Cite journal |last1=久敏 |first1=伊藤 |last2=真平 |first2=上澤 |date=2017 |title=鬼界カルデラにおける鬼界アカホヤ噴火以前の大噴火について |url=https://www.jstage.jst.go.jp/article/geosocabst/2017/0/2017_023/_article/-char/ja/ |journal=日本地質学会学術大会講演要旨 |volume=2017 |pages=023 |doi=10.14863/geosocabst.2017.0_023}}</ref>

=== Kikai-Koabiyama eruption ===
The Kikai-Koabiyama (K-Kob) pyroclastic flows are rhyolitic and are distributed across most of Takeshima and the plateau-like area on the northwest side of the caldera rim of Satsuma Iwo-Jima. They consist of numerous thin flow units and fill the basins in the basement, exhibiting significant variation in thickness. In Takeshima, the pyroclastic flows are thick, ranging from {{Convert|20-100|m|ft|abbr=on}}, whereas in Iwo Jima, they are relatively thin, measuring a few to {{Convert|30|m|ft|abbr=on}}.<ref name="gbank" /><ref name=":2" />

The eruption of the K-Kob pyroclastic flows has been dated using [[K–Ar dating|K-Ar dating]] to be {{Val|140000|20000|fmt=commas}} years before present.<ref name="gbank" /> While no distal tephra from this eruption has been reported, a tephra layer with potential geochemical and age correlation has been discovered in [[Lake Suigetsu]].<ref>{{Cite journal |last1=Maruyama |first1=Seiji |last2=Takemura |first2=Keiji |last3=Hirata |first3=Takafumi |last4=Yamashita |first4=Tohru |last5=Danhara |first5=Tohru |date=2019-08-11 |title=Major and trace element abundances in volcanic glass shards in visible tephras in SG93 and SG06 drillcore samples from Lake Suigetsu, central Japan, obtained using femtosecond LA–ICP–MS |journal=Journal of Quaternary Science |volume=35 |issue=1–2 |pages=66–80 |doi=10.1002/jqs.3124 |issn=0267-8179|doi-access=free }}</ref>

===Kikai-Tozurahara eruption===
Kikai-Tozurahara (K-Tz) [[tephra]] is a widespread rhyolitic tephra layer of [[Late Pleistocene]] age, attributed to a large [[Volcanic explosivity index|VEI]]-7 eruption from the Kikai caldera.<ref name=":0">{{Cite journal |last1=洋 |first1=町田 |last2=房夫 |first2=新井 |date=1983 |title=101. 鬼界カルデラ起源の新広域テフラと九州における更新世後期大火砕流の噴出年代(日本火山学会 1983 年度春季大会講演要旨) |url=https://www.jstage.jst.go.jp/article/kazanc/28/2/28_KJ00003453684/_article/-char/ja/ |journal=火山.第２集 |volume=28 |issue=2 |pages=206 |doi=10.18940/kazanc.28.2_206_2}}</ref> This layer is confirmed to have a wide distribution, extending from south [[Kyushu]] to eastern [[Honshu]] and reaching the [[Pacific Ocean]],<ref name=":1">{{Cite journal |last=Machida |first=Hiroshi |date=1999 |title=The stratigraphy, chronology and distribution of distal marker-tephras in and around Japan |url=https://linkinghub.elsevier.com/retrieve/pii/S0921818199000089 |journal=Global and Planetary Change |language=en |volume=21 |issue=1–3 |pages=71–94 |doi=10.1016/S0921-8181(99)00008-9|bibcode=1999GPC....21...71M |url-access=subscription }}</ref> and possibly including the [[Shandong Peninsula]].<ref>{{Cite journal |last1=Eden |first1=Dennis N. |last2=Froggatt |first2=Paul C. |last3=Zheng |first3=Honghan |last4=Machida |first4=Hiroshi |date=1996-01-01 |title=Volcanic glass found in Late Quaternary Chinese loess: A pointer for future studies? |url=https://dx.doi.org/10.1016/1040-6182%2895%2900074-7 |journal=Quaternary International |language=en |volume=34-36 |pages=107–111 |doi=10.1016/1040-6182(95)00074-7 |bibcode=1996QuInt..34..107E |issn=1040-6182|url-access=subscription }}</ref> The proximal equivalents of K-Tz are the Nagase [[pyroclastic flow]] and the Nishinoomote [[pyroclastic surge]]s.<ref name=":0" /><ref>{{Cite journal |last=信治 |first=長岡 |date=1988 |title=最終間氷期末に起きた鬼界カルデラの珪長質火砕流噴火と火砕サージの形成 |url=https://www.jstage.jst.go.jp/article/jgeography1889/97/3/97_3_156/_article/-char/ja/ |journal=地學雜誌 |volume=97 |issue=3 |pages=156–169 |doi=10.5026/jgeography.97.3_156|doi-access=free }}</ref> The combined bulk volume of both distal and proximal deposits is estimated to exceed {{Convert|150|km3|mi3|abbr=on}}.<ref name=":1" />

In [[Marine isotope stages|marine isotope stratigraphy]] (MIS), K-Tz is located between MIS 5.2 and 5.3, providing a loosely constrained preliminary eruption age of approximately 95,000 years before present.<ref name=":1" /> More reliable age constraints were imposed by the high-resolution chronology derived from the Lake Suigetsu sediment sequence, which yielded an age of {{Val|94500|4800|fmt=commas}} years before present for this eruption.<ref>{{Cite journal |last1=Albert |first1=Paul G. |last2=Smith |first2=Victoria C. |last3=Suzuki |first3=Takehiko |last4=McLean |first4=Danielle |last5=Tomlinson |first5=Emma L. |last6=Miyabuchi |first6=Yasuo |last7=Kitaba |first7=Ikuko |last8=Mark |first8=Darren F. |last9=Moriwaki |first9=Hiroshi |last10=Nakagawa |first10=Takeshi |date=2019 |title=Geochemical characterisation of the Late Quaternary widespread Japanese tephrostratigraphic markers and correlations to the Lake Suigetsu sedimentary archive (SG06 core) |url=https://linkinghub.elsevier.com/retrieve/pii/S1871101418300967 |journal=Quaternary Geochronology |language=en |volume=52 |pages=103–131 |doi=10.1016/j.quageo.2019.01.005|bibcode=2019QuGeo..52..103A |hdl=2262/93449 |s2cid=134899116 |hdl-access=free }}</ref>

===Kikai-Akahoya eruption===
[[File:Kikai K-Ah tephra 7,3ka.svg|thumb|left|alt=Impact|Kikai-Kikai-Akahoya (K-Ah) [[tephra]] and pyroclastic flow impact from [[Akahoya eruption|Kikai-Akahoya eruption]]]]
{{main|Akahoya eruption}}
The caldera was the source of the [[Akahoya eruption|Kikai-Akahoya eruption]], one of the largest eruptions during the [[Holocene]] (10,000&nbsp;years ago to present) that produced the Kikai-Akahoya (K-Ah) [[tephra]].<ref name="Tsuji2018">{{cite journal|first1=Tomohiro |last1=Tsuji|first2= Michiharu |last2=Ikeda|first3= Akira |last3=Furusawa|first4= Chisato |last4=Nakamura|first5= Kiyoshi |last5=Ichikawa|first6= Makoto |last6=Yanagida|first7= Naoki |last7=Nishizaka|first8= Kozo |last8=Ohnishi|first9= Yuki |last9=Ohno|title=High resolution record of Quaternary explosive volcanism recorded in fluvio-lacustrine sediments of the Uwa basin, southwest Japan |journal=Quaternary International |volume=471 |year=2018 |pages=278–297 |issn=1040-6182 |doi=10.1016/j.quaint.2017.10.016 |doi-access=free |bibcode=2018QuInt.471..278T }}</ref> Between 7,200 and 7,300&nbsp;years ago,<ref name="Tsuji2018"/><ref name="Okuno2019">{{cite journal |last1=Okuno |first1=Mitsuru |date=2019-04-15 |title=Chronological study on widespread tephra and volcanic stratigraphy of the past 100,000 years |url=https://www.jstage.jst.go.jp/article/geosoc/125/1/125_2018.0069/_article/-char/en |journal=The Journal of the Geological Society of Japan |volume=125 |issue=1 |pages=41–53 |doi=10.5575/geosoc.2018.0069 |issn=1349-9963 |s2cid=146526393|doi-access=free }}</ref><ref name="Smith2013">{{cite journal|first1=Victoria C. |last1=Smith|first2= Richard A. |last2=Staff|first3= Simon P.E. |last3=Blockley|first4= Christopher Bronk |last4=Ramsey|first5= Takeshi |last5=Nakagawa|first6= Darren F. |last6=Mark|first7= Keiji |last7=Takemura|first8= Toru |last8=Danhara |title=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 |journal= Quaternary Science Reviews |volume=67|year=2013 | pages=121–137 |issn=0277-3791 |doi=10.1016/j.quascirev.2013.01.026 |bibcode=2013QSRv...67..121S |url=https://www.sciencedirect.com/science/article/pii/S0277379113000413 |url-access=subscription }}</ref> [[pyroclastic flow]]s producing Koya [[ignimbrite]] from that eruption reached the coast of southern [[Kyūshū]] up to {{convert|100|km|mi|abbr=on}} away, and ash fell as far as [[Hokkaido]]. The eruption produced about {{cvt|133|–|183|km3|cumi}}&nbsp;[[Dense rock equivalent|DRE]], most of it tephra.<ref>{{cite journal |doi=10.1016/j.jvolgeores.2024.108017 |author1=Satoshi Shimizu |author2=Reina Nakaoka |author3=Nobukazu Seama |author4=Keiko Suzuki-Kamata |author5=Katsuya Kaneko |author6=Koji Kiyosugi |author7=Hikaru Iwamaru |author8=Mamoru Sano |author9=Tetsuo Matsuno |author10=Hiroko Sugioka |author11=Yoshiyuki Tatsumi |date=2024 |title= Submarine pyroclastic deposits from 7.3 ka caldera-forming Kikai-Akahoya eruption|journal=Journal of Volcanology and Geothermal Research |volume= |issue=108017 |pages=|doi-access=free }}</ref><ref name=GVP>{{cite gvp|vn=282060|title=Kikai: Eruptive History|accessdate=2024-02-26}}</ref> giving it a [[Volcanic Explosivity Index]] of 7,<ref name=GVP /> so making it one of the most explosive in the last 10,000 years, ranking alongside the eruptions of [[Santorini]], [[Paektu Mountain|Paektu]], [[Crater Lake]], [[Kurile Lake]], [[Lake Segara Anak|Samalas]] and [[Mount Tambora|Tambora]].<ref>{{cite web |url=http://www.allcountries.org/ranks/volcano_explocivity_index_ranks.html |title=Large Volcano Explocivity Index |work=Countries of the World |access-date=2014-04-24}}</ref>

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.<ref>{{cite web|url=https://www.sainsbury-institute.org/e-bulletin/april-2021/after-a-super-volcanic-eruption-a-new-project-on-social-ecological-impacts-of-the-kikai-akahoya-disaster-7300-years-ago/ |access-date=2022-09-18 |title=After a Super Volcanic Eruption: a new project on social-ecological impacts of the Kikai-Akahoya disaster, 7,300 years ago| year=2021 |first1=Uchiyama |last1=Junzo}}</ref>