Kikai Caldera

Kikai Caldera (鬼界カルデラ Kikai karudera) is a massive, mostly submerged caldera up to 19 kilometres (12 mi) in diameter in the Ōsumi Islands of Kagoshima Prefecture, Japan. It is the remains of the ancient eruption of a gigantic volcano. Its geographic coordinates are: Latitude (dd.) 30.79 and Longitude (dd.) 130.31[1]

Kikai Caldera
Kikai Caldera Relief Map, SRTM, English
Highest point
PeakMount Iō (Iōjima) (Iōjima, Ōsumi Islands, Japan)
Elevation704 m (2,310 ft)
Length17 km (11 mi) NS
Width20 km (12 mi) EW
Native name鬼界カルデラ
StateKagoshima Prefecture
RegionŌsumi Islands
DistrictKagoshima District
Age of rock6,300 to 95,000 years ago

Eruption history

Kikai Caldera was the source of the Akahoya eruption, one of the largest eruptions during the Holocene (10,000 years ago to present). About 6,300 years ago or 4,300 BC, pyroclastic flows 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,[2] giving it a Volcanic Explosivity Index of 7[3] and making it one of the most explosive in the last 10,000 years, ranking alongside Santorini, Changbaishan, Crater Lake, Kurile Lake and Tambora.[4]

Kikai is still an active volcano. Minor eruptions occur frequently on Mount Iō (硫黄岳 Iō-dake), one of the post-caldera subaerial volcanic peaks on Iōjima (硫黄島 Iō-jima). 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.[5]

2015 Satsuma-Iojima Iodake
Mount Iōdake. May, 2015. Taken from the east.

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.

See also


  1. ^ "Kikai | Volcano World | Oregon State University". Retrieved 2017-04-11.
  2. ^ Kikai – Eruptive history, Global Volcanism Program. Smithsonian Institution.
  3. ^ Johnston, Eric, "Latest volcano show: Shinmoe", The Japan Times, 1 March 2011, p. 3.
  4. ^ "Large Volcano Explocivity Index". Countries of the World. Retrieved 2014-04-24.
  5. ^ "Global Volcanism Program | Kikai". Retrieved 2017-04-07.

External links

5th millennium BC

The 5th millennium BC spanned the years 5000 through 4001 BC. It saw the spread of agriculture from Western Asia throughout Southern and Central Europe.

Urban cultures in Mesopotamia and Anatolia flourished, developing the wheel. Copper ornaments became more common, marking the beginning of the Chalcolithic. Animal husbandry spread throughout Eurasia, reaching China.

World population growth relaxes after the burst due to the Neolithic Revolution. World population is largely stable, at roughly 40 million, with a slow overall growth rate at roughly 0.03% p.a.

Akahoya eruption

The Akahoya eruption was the strongest known volcanic eruption of the Kikai Caldera in Kyūshū, Japan. It ejected about 150 cubic kilometres (36 cu mi) of volcanic material, giving it a 7 on the Volcanic Explosivity Index. The Akahoya eruption is one of only six known eruptions reaching that magnitude during the Holocene, or the last twelve thousand years. It dramatically changed vegetation in Southern Kyūshū. However newer surveys put this volume of ejecta at 500 km3.Archaeologically it has been dated around 7,300 cal. BP during the Earliest Jōmon period, but it has also been radiocarbon dated to 6,500 BP. This eruption has been linked to the end of the Initial Jomon period, which would place the Jomon alongside the Minoan Culture in meeting its end by way of massive volcanic eruptions. This gives more credence to cultural traditions that maintain stories of established cultures vanishing quickly and completely, and invites further study into volcanic activity on human societal development.


A caldera is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber/reservoir in a volcanic eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is lost. The ground surface then collapses downward into the emptied or partially emptied magma chamber, leaving a massive depression at the surface (from one to dozens of kilometers in diameter). Although sometimes described as a crater, the feature is actually a type of sinkhole, as it is formed through subsidence and collapse rather than an explosion or impact. Only seven caldera-forming collapses are known to have occurred since 1900, most recently at Bárðarbunga volcano, Iceland in 2014.


Denshima (デン島), also known as Yuze (湯瀬), is an uninhabited volcanic pillar located in the Ōsumi Islands and belonging to Kagoshima Prefecture, Japan.

Fukui Prefectural Varve Museum

Fukui Prefectural Varve Museum is a geological and archeological museum located in Wakasa, Mikatakaminaka District, Fukui Prefecture, Japan. It features varve ranging from now back to 70,000 years found at the bottom of Lake Suigetsu. The special chairman is Kazuma Yamane.

Geography of Japan

Japan is an island country comprising a stratovolcanic archipelago over 3,000 km (1,900 mi) along East Asia's Pacific coast. It consists of 6,852 islands. The 5 main islands are Hokkaido, Honshu, Kyushu, Shikoku and Okinawa. There are 6,847 'remote islands'. The Ryukyu Islands and Nanpō Islands are south and east of the main islands.

The territory extends 377,973.89 km2 (145,936.53 sq mi). It is the 4th largest island country in the world and the largest island country in East Asia. Japan has the sixth longest coastline 29,751 km (18,486 mi) and the eighth largest Exclusive Economic Zone of 4,470,000 km2 (1,730,000 sq mi) in the world.The terrain is mostly rugged and mountainous with 66% forest. The population is clustered in urban areas on the coast, plains and valleys. Japan is located in the northwestern Ring of Fire on multiple tectonic plates. East of the Japanese archipelago are three oceanic trenches. The Japan Trench is created as the oceanic Pacific Plate subducts beneath the continental Okhotsk Plate. The continuous subduction process causes frequent earthquakes, tsunami and stratovolcanoes. The islands are also affected by typhoons. The subduction plates have pulled the Japanese archipelago eastward, created the Sea of Japan and separated it from the Asian continent by back-arc spreading 15 million years ago.The climate of the Japanese archipelago varies from humid continental in the north (Hokkaido) to humid subtropical and tropical rainforest in the south (Okinawa Prefecture). These differences in climate and landscape have allowed the development of a diverse flora and fauna, with some rare endemic species, especially in the Ogasawara Islands.

Japan extends from 20° to 45° north latitude (Okinotorishima to Benten-jima) and from 122° to 153° east longitude (Yonaguni to Minami Torishima). Japan is surrounded by seas. To the north the Sea of Okhotsk separates it from the Russian Far East, to the west the Sea of Japan separates it from the Korean Peninsula, to the southwest the East China Sea separates the Ryukyu Islands from China and Taiwan, to the east is the Pacific Ocean.

Iōjima (Kagoshima)

Iōjima (硫黄島), also known as Satsuma Iōjima (薩摩硫黄島) or Tokara Iōjima (吐噶喇硫黄島), is one of the Satsunan Islands, usually classed with the Ōsumi Islands, belonging to Kagoshima Prefecture, Japan. Along with Takeshima and Kuroshima, it makes up the three-island village of Mishima, Kagoshima Prefecture, Japan. The island, 11.65 km² in area, has a population of 142 persons.


Kikai is a Japanese name.


Kikai Caldera

Kikai Island

The Ryukyuan language spoken on this island

Kikai, KagoshimaPersonal names

Hiroh Kikai (b. 1945), photographer

Kikai, Kagoshima

Not to be confused with Kikai Caldera, which is submerged in the Ōsumi Islands

Kikai (喜界町, Kikai-chō) is a town located on Kikaijima, in Ōshima District, Kagoshima Prefecture, Japan.

In June 2013 the town had an estimated population of 7,657 and a population density of 134 persons per km². The total area is 56.94 km². The economy of the town is based on sugar cane, shōchū refining and seasonal tourism.


Kikaijima (喜界島, also Kikai-ga-jima; Kikai: キャー Kyaa, Northern Ryukyuan: ききや Kikiya) is one of the Satsunan Islands, classed with the Amami archipelago between Kyūshū and Okinawa.The island, 56.93 square kilometres (21.98 sq mi) in area, has a population of approximately 7,657 persons. Administratively the island forms the town of Kikai, Kagoshima Prefecture. Much of the island is within the borders of the Amami Guntō Quasi-National Park.

List of large volcanic eruptions

This is a sortable summary of the pages Timeline of volcanism on Earth, List of Quaternary volcanic eruptions, and Large volume volcanic eruptions in the Basin and Range Province. Uncertainties as to dates and tephra volumes are not restated, and references are not repeated. Volcanic Explosivity Index (VEI) values for events in the Miocene epoch sometimes lack references. They are given as VEI-equivalent, as orientation of the erupted tephra volume. Please note that this is not a comprehensive list, and some events are missing from the table.

List of volcanoes in Japan

This is a list of active and extinct volcanoes in Japan. Orange background indicates a volcano considered active by the Japan Meteorological Agency.

Mount Iō (Iōjima)

Mount Iō (硫黄岳, Iō-dake) also Mount Iwo is an active rhyolitic lava dome on Iōjima in Kagoshima Prefecture, Japan. It sits within the borders of the town of Mishima.

The mountain is made up of non-alkali felsic rock and pyroclasitic flows.

Natural disasters in Japan

Japan is one of the countries most affected by natural disasters, mainly due to it being in the Ring of Fire. Two out of the five most expensive natural disasters in recent history have occurred in Japan, in 1995 and 2011, costing $181 billion. Japan has also been the site of some of the 10 worst natural disasters of the 21st century. Many types of natural disasters occur in Japan such as tsunamis, floods, typhoons, earthquakes, cyclones, and even volcanic eruptions. The country has gone through thousands of years of natural disasters, affecting its economy, development, and social life. Some other major disasters in Japan were more recent, such as the January 1995 Great Hanshin earthquake and the March 2011 Tōhoku earthquake and tsunami, which triggered the Fukushima Daiichi nuclear disaster.

Plinian eruption

Plinian eruptions or Vesuvian eruptions are volcanic eruptions marked by their similarity to the eruption of Mount Vesuvius in 79 AD, which destroyed the ancient Roman cities of Herculaneum and Pompeii. The eruption was described in a letter written by Pliny the Younger, after the death of his uncle Pliny the Elder.

Plinian/Vesuvian eruptions are marked by columns of volcanic debris and hot gases ejected high into the stratosphere, the second layer of Earth's atmosphere. The key characteristics are ejection of large amount of pumice and very powerful continuous gas-driven eruptions. According to the Volcanic Explosivity Index, Plinian eruptions have a VEI of 4, 5 or 6, sub-Plinian 3 or 4, and ultra-Plinian 6, 7 or 8.

Short eruptions can end in less than a day, but longer events can continue for several days or months. The longer eruptions begin with production of clouds of volcanic ash, sometimes with pyroclastic surges. The amount of magma erupted can be so large that it depletes the magma chamber below, causing the top of the volcano to collapse, resulting in a caldera. Fine ash and pulverized pumice can deposit over large areas. Plinian eruptions are often accompanied by loud noises, such as those generated by the 1883 eruption of Krakatoa. The sudden discharge of electrical charges accumulated in the air around the ascending column of volcanic ashes also often causes lightning strikes as depicted by the English geologist George Julius Poulett Scrope in his painting of 1822.

The lava is usually dacitic or rhyolitic, rich in silica. Basaltic, low-silica lavas are unusual for Plinian eruptions; the most recent basaltic example is the 1886 eruption of Mount Tarawera on New Zealand's North Island.


Shunkan (俊寛) (c. 1143 – 1179) was a Japanese monk who, after taking part in the Shishigatani plot to overthrow Taira no Kiyomori, was exiled along with two others to Kikai-ga-shima. His story is featured in the Heike monogatari, and in a number of traditional derivative works, including the Noh play Shunkan and jōruri play Heike Nyogo-ga-shima. Twentieth century authors Kan Kikuchi and Ryūnosuke Akutagawa also produced works entitled Shunkan.

Shōwa Iōjima

Shōwa Iōjima (昭和硫黄島), also known as Shōwa Shintō (昭和新島), is one of the Satsunan Islands, usually classed with the Ōsumi Islands, belonging to Kagoshima Prefecture, Japan. A deserted volcanic island, it is located just off the northern shore of Iōjima, Kagoshima.


A supervolcano is a large volcano that has had an eruption of magnitude 8, which is the largest value on the Volcanic Explosivity Index (VEI). This means the volume of deposits for that eruption is greater than 1,000 cubic kilometers (240 cubic miles).Supervolcanoes occur when magma in the mantle rises into the crust but is unable to break through it and pressure builds in a large and growing magma pool until the crust is unable to contain the pressure. This can occur at hotspots (for example, Yellowstone Caldera) or at subduction zones (for example, Toba). Large-volume supervolcanic eruptions are also often associated with large igneous provinces, which can cover huge areas with lava and volcanic ash. These can cause long-lasting climate change (such as the triggering of a small ice age) and threaten species with extinction. The Oruanui eruption of New Zealand's Taupo Volcano (about 26,500 years ago) was the world's most recent super eruption at a VEI-8 eruption.

Volcanic Explosivity Index

The Volcanic Explosivity Index (VEI) is a relative measure of the explosiveness of volcanic eruptions. It was devised by Chris Newhall of the United States Geological Survey and Stephen Self at the University of Hawaii in 1982.

Volume of products, eruption cloud height, and qualitative observations (using terms ranging from "gentle" to "mega-colossal") are used to determine the explosivity value. The scale is open-ended with the largest volcanoes in history given magnitude 8. A value of 0 is given for non-explosive eruptions, defined as less than 10,000 m3 (350,000 cu ft) of tephra ejected; and 8 representing a mega-colossal explosive eruption that can eject 1.0×1012 m3 (240 cubic miles) of tephra and have a cloud column height of over 20 km (66,000 ft). The scale is logarithmic, with each interval on the scale representing a tenfold increase in observed ejecta criteria, with the exception of between VEI-0, VEI-1 and VEI-2.


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