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Wednesday, October 12, 2016

The Every Volcano In Japan List

Like the title says, this is a list of all the volcanoes in Japan… all 118 of them. I must have been stupid to have done this. I must be up around 40+ hours...

It does not mean that all of theses listed volcanoes are active… some are dormant, and others are extinct.

First off, some definitions:

Kazan means 'volcano'. Here's another reason why I looked at learning the Japanese language and said, I'm not smart enough: Taken from "Volcanoes of Japan (Third Edition)" issued by Geological Survey of Japan in 2013. In Japanese, volcano names basically comprise "name of a mountain or island + volcano (in Japanese)", for example, Fuji Volcano (Fuji Kazan). Kazan means volcano in Japanese. The "name" used in this database is the officially accepted name although there are some exceptions.

In Japanese, locality names ending with “...-yama”, “...-san”, “...-zan”, “...-take”, “...-dake”, “...-sen”, “...-zen” and “...-mine” mean “mountain”. The spelling is not consistent, however, and some such names are written with a space between words. For example, “Asama”, “Asama-yama”, “Asama Yama”, “Asamayama” and “Asama-Yama” are all synonymous. It is also correct to say “Mt. Asama” or “Mt. Asamayama”. In the case of mountains that are also volcanoes, terms such as “Asama Volcano”, “Asama-yama Volcano”, or “Asamayama Volcano” are used. In some case, both “... yama” and “...-san” are used for the same mountain (volcano).

In Japanese, locality names ending with “...shima”, “...-jima”, “...Shima” and “...Jima” mean “island”. "Miyake Jima" can also be spelled “Miyake-Jima”, “Miyake-jima” and “Miyakejima”. When an island is a volcano, it is called “Miyakejima Volcano” or “Miyake Volcano”.

1. In some cases, endings for “mountain” or “island” cannot be separated from the place name. An example is “Nii-jima” which is never written as “Nii” or “Nii Volcano”. Similarly “Dai-sen” is never written “Dai” or “Dai Volcano”.

2. Due to the limited number of Japanese syllables, “Fuji Volcano” can also sometimes be spelled “Huzi Volcano”, which is pronounced identically in Japanese but appears at different places in an alphabetical list. There are several similar cases.

3. Prolonged vowels are part of the Japanese language but are unknown in English. Some localities can thus be spelled in different ways, e.g. “Oshima”, “Ooshima” and “Ohshima”, all used for the same locality.

4. When the letters “m” or “n” appear before the letters “p”, “b” or “m”, as in “Sambe” and “Sanbe”, both can be used for the same locality. These letters should be unified as “n” in this database. 

Riiii-iight. Enough of that...
It gets easier once we stop looking at how and why the Japanese have 50 different ways of saying volcano...

Active Volcano: a volcano is a volcano that has had at least one eruption during the past 10,000 years. An active volcano might be erupting or dormant;

Erupting Volcano: I’m pretty sure you know that it means it is an active volcano that is currently having an eruption;

Dormant Volcano: an active volcano that is not erupting, but supposed to erupt again.

Extinct Volcano: a volcano that has not erupted for at 10,000 years or more, and is not expected to erupt again.

Fumarole example - any place on a volcano where gases vent out.
Three types of volcano (knowing that a volcano can exhibit multiple forms of each):
  1. Composite/stratovolcano: steep-sided cones formed from layers of ash and lava flow. Eruptions are usually pyroclastic flow, rather than lava.
    Mt. Fuji is a classic example of a stratovolcano, rising steeply.
    These volcanoes reach a height of over 8,000 feet. They are a threat to life. Eruptions are considered explosive because the lava is thick… it cools quickly, which is why these volcanoes look the way they do;  
  2. Shield: low, with gentle-sloped sides. Eruptions are non-explosive. The lava is a fast-moving, thinner variety of lava that can flow for miles.
    An example of a shield volcano - see how wide it is, with a gentle sloping rise.
    The eruptions tend to happen more often than other volcanic types, but are not as violent;
  3. Dome: have steeper sides than Shield Volcanoes, because the lava is thicker and stickier and can not very flow far before it cools… basically it ends up building the volcano, rather than traveling for miles down onto a village. Domes occur within volcanoes, within the caldera (cauldron).
A lava dome within a volcano.
Types of Volcanic Ejection:
  • Pyroclastic flow is super-heated mix of steam, ash, rock and dust - with temperatures over 400C degrees. With a steep volcano, pyroclastic flows can reach a speed of 160 kph (100 mph) - see below;

  • Lahars are volcanic mudflow created when water and ash mixes - see below:
  • Phreatic: usually a steam-driven explosion when the hot ejecta comes in contact with underground or surface water - a perfect example is the video at the top of this list showing the pyroclstic explosion;
  • Caldera: a large cauldron-like volcanic depression, a crater, like you might expect to see if you stood at the lip of a volcano and looked down and in;
  • Lava Dome: a roughly circular mound-shaped protrusion formed from a slow expulsion viscous lava from a volcano.
Bonus Volcanoes:
Supervolcano. This is not a mountain, rather it forms from a depression in the Earth’s crust with a column of magma rising, where it pools in the crust melting surrounding rock for thousands of years. This causes a build-up of pressure… and when the area has had enough - kaboom! - the magma lake drains and the land above collapses down creating a caldera, which is a cauldron-like crater. Like the name suggests, the eruption occurs with a very big explosion.
Now… a supervolcano is also considered to be any volcano that erupts and ejects matter volume greater than 1,000 cubic meters (240 cubic miles).

Seamount: a volcano that grows up from the seafloor, but does not breach the surface, except perhaps when it expels material during an eruption. It is also known as a submarine volcano, a term I use quite a bit below.

For those of you seeking more information than I care to dumb down so I can understand it, take a look at the Wikipedia page for the Volcanic Explosivity Index.

It is not confirmed, but scientist believe there is a strong link between volcanic activity and earthquakes. They are not sure if one precedes the other, but a strong link does appear to exist.

Earthquake swarms are events where a local area experiences sequences of many earthquakes striking in a relatively short period of time. The length of time used to define the swarm itself varies, but may be of the order of days, weeks, or months. They do tend to occur at or very near active volcanoes.

So… Japan has a total of 118 volcanoes, 100 of which are considered to be active (including dormant), with 47 of them (really, 47  - my number) considered very active… which includes Mt. Fuji, as an FYI.

Of those 100 active volcanoes in Japan, it represents 10 percent of the global total.

The following data is taken in part(s) from They did the hard work… I’m taking the more practical aspects of it for here.

Oh, and in case you were wondering just how the heck scientist are able to guess the dates of such old volcanic activity, they use: Radiocarbon and Tephrochronology dating.

And, if you are also wondering why more modern eruptions seem to be ~approximations, it’s because the eruptions occurred in areas with people being present to 100% confirm or deny the event.

Hokkaido (20 volcanoes):

Akan: (阿寒岳, Akan-dake) is one of Hokkaido's most active explosive volcanoes. The stratovolcano has a 24km x 13 km diameter caldera. There are nine overlapping cones, with the summit containing three craters. Part of Akan National Park, Lake Akan is home to the rare marimo green algae that grows to soccer-ball size.  At the only town near Lake Akan—Akankohan— there are many hot springs and bokke (bubbling mid pools). Known eruptions are: 2008, 2006, 1988, 1966, 1965, 1964, 1962, 1960, 1959, 1958, 1957, 1956, 1955, 1954, 1951(?)-52, ~1927, ~1808, 1800. There has been a plethora of earthquakes in the area in July27-28 of 2015. Earthquakes and volcanoes are suspected of being linked, but scientists aren’t sure if they are, let alone which precedes the other.
Mount Akan, smoking in 2015.
Daisetsu; a group of eight stratovolcanoes, lava domes and a two kilometer wide caldera in the Daisetsuzan National Park. Of the volcanoes in this cluster of dormant volcanoes and their explosive eruptions, Asahi-dake is the highest peak of the chain and the highest mountain in Hokkaido. Known eruptions are ~1739, 550BC, ~1450BC, ~2800BC, and ~3200BC.

E-san: (恵山, or えさん) is a small stratovolcano. An eruption in 1846 formed a lahar that killed many people. Known eruptions: 1874, 1846, ~3900BC.

Komaga-take: (北海道駒ヶ岳) is one of Japan’s most active volcanoes, though it has been dormant since 2000. This is a truncated stratovolcano. Known eruptions are: 2000, 1998, 1996, 1942, 1937, 1935 (?), 1929, 1928 (?), 1924, 1923, 1922, 1919, 1905, 1888, 1856, 1784, 1765, 1710 (?), 1694, 1640, and radiocarbon-dated eruptions circa 4350BC, 4500BC, and 4600BC.

Kutcharo: contains a large 26 kilometer x 20 kilometer diameter caldera (Lake Kucharo), as well as the Atosanupuri volcano. The caldera was formed via many explosive eruptions 30,000 to 340,000 years ago. Known eruptions are: circa 1320;

Kuttara: This is a group of small stratovolcanoes, lava domes, pyroclastic cones, and one three-kilometer wide caldera filled by Lake Kuttara. There’s also Hell Valley (Jigokudani), a 450 meter diameter crater formed 200,000 years previous. There are 11 hot springs, hot steam vents, geysers and fumaroles. The valley also contains the sulphur pool Oyunuma. Archeo-geologists have determined that the first of five major eruptions occurred there 60,000 years ago. Known eruptions are: ~1820, ~200, 8050 BC, with other earlier ones, including 40,000 and 60,000 years ago.

Mashu: (my personal favorite volcano, as it’s my middle name… oh yeah and some guy I know. Anyhow, the dormant volcano with explosive tendencies is a 7 km wide caldera formed 7,000 years ago. The caldera houses Lake Mashu (摩周湖 Mashū-ko), known for its very clear water. In the center of the lake is a small island made up of a submerged lava dome and is known as Kamuishu;

Nigorigawa: Extinct volcano… though it is also listed as merely dormant… it lasted erupted ~10,000 BC. That’s 12,000 years ago. By all definitions, that is one extinct volcano;

Nipesotsu-Maruyama: (ニペソツ・丸山火山群, Nipesotsu-Maruyama-kazangun )a group of overlapping stratovolcanoes and lava domes with fumaroles in the center crater. Known eruptions of this dormant volcano are: 1898, 1700BC;

Niseko: (ニセコ火山群, Niseko-kazangun) is a group of stratovolcanoes and lava domes. Last known magma eruption of the now dormant volcano was ~4900BC. There are hot springs and fumaroles in the area;

Oshima-Oshima: (渡島大島) dormant, but explosive enough that they had to name it twice. A 1741 eruption is said to have caused a tsunami that killed nearly 1,500 people. Seismic disturbances did occur under the volcano last in 1996. Known eruptions: 1790, 1786(?), 1759, 1741-42;

Rausu: (羅臼岳 Rausu-dake) is an active, but dormant stratovolcano, with its summit containing lava domes. Known eruptions are, according to field evidence, to have occurred between 1750-1850.

Rishiri: (利尻山, Rishiri-zan) forms a small island 20 kilometers west of the northern tip of Hokkaido. The stratovolcano is considered dormant, last erupting in ~6650BC. It is part of Rishiri-Rebun-Sarobetsu National Park.

Shikaribetsu: (然別火山群 Shikaribetsu-kazangun) is a group of lava domes within Daisetsuzan National Park. The extinct volcano includes Mount Ishikari, Mount Yuniishikari, Mount Otofuke and Mount Higashinupukaushi.

Shikotsu: A dormant stratovolcano that last erupted in 1981, there was some seismic activity and bloating recorded in 2013. There is a 13-kilometer diameter caldera containing the 3260 meter deep Lake Shikotsu, which is Japan’s second-largest crater lake, and the northernmost one that doesn’t freeze over in the winter. The caldera was formed by eruptions circa 31-34,000 years ago. Known eruptions are: 1981, 1978-79, 1978, 1954-55, 1954, 1953, 1951, 1951, 1944, 1936, 1936, 1933, 1931, 1928-29, 1928, 1926, 1923, 1921, 1920, 1919, 1918, 1917, 1909, 1894, 1894, 1887, 1886, 1885, 1883, 1874, 1871(?), 1867, 1804-17, 1739, 1667

Shiretoko-Iwo-zan: an active stratovolcano with two large craters at the summit. It is known as a sulfur mountain because it erupted sulphur during the 1889 and 1936 eruptions. Known eruptions are: 1936, 1890, 1889, ~1880, 1876, ~1857.

Shiribetsu: Extinct. Last known eruptions were several hundred thousand years ago.

Tokachi: (十勝岳 Tokachidake) is a group of active stratovolcanoes and lava domes with explosive eruptions. Known eruptions are: 2004, 1988-89, 1985, 1962, 1961, 1959, 1958, 1957, 1956, 1954, 1952, 1931, 1928, 1928, 1925-27, 1889, 1887, 1857;

Usu: (有珠山) is a small stratovolcano located along the rim of the 110,000-year-old Toya caldera. In the center of the 10-kilometer-wide lake-filled caldera contains the mini island of Naka-jima, which is essentially forested lava domes conjoined. Known as an explosive but dormant volcano, known eruptions are: 2000-01, 1977-82, 1944-45, 1910, 1853, 1822, 1769, 1663, 1638, 1626, ~1611. It’s last eruption caused 13,000 residents to be evacuated from their homes. remember, one can NOT evacuate 13,000 people. That would be painful.

Yote: (羊蹄山, Yōteizan) is a stratovolcano whose summit contains a 700 meter wide crater. Known eruption: ~1050BC;

Honshu (47 volcanoes):

Abu: is, holy smokes, a group of 56 small volcano craters about 80 kilometers from Hiroshima, covering some 400 square kilometers. The most recent eruption is guesstimated to have occurred in 6850BC.

Adatara: A group of overlapping stratovolcanoes, with just Minowa-yama—the highest peak—the only active volcano.  Still, the dormant chain is known for its fumaroles and hot springs. It’s summit crater was the site of a sulphur mine. An eruption in 1900 killed 72 workers there. The volcano began with eruptions 550,000, 350,000 and 200,000 years ago. Known eruptions in modern times are: 1996, 1900, 1899 and ~1813.

Akagi: is a wide stratovolcano within Akagi National Park. It has a 3 kilometer x 4 kilometer diameter summit caldera, containing Lake Ono. No one is sure if the volcano did erupt in 1938 and 1251, or even the 9th century.

Akita-Komaga-take: considered “restless”, this is an active volcanoe, with some weak seismic activity (earthquakes) felt in March of 2016. However, because of past history, scientists do not believe that this volcano shows much seismic activity before an eruption as evidenced (or not evidenced) after the 1970 eruption. Known eruptions are: 1970-71 featuring strombolian activity and lava flow, 1932, 1902, 1890-91, ~1100, ~807, ~400, ~50BC, ~200BC, ~350BC, ~1450BC, ~5950BC, ~6150, ~6350BC, ~7100BC, ~7850BC, ~8300BC, ~8800BC.
Akita-Komaga-take volcano.
Akita-Yake-yama: an active, but dormant stratovolcano that ejects mud when erupting among other matter. The last magma eruption is considered to have been about 5000 years ago. Along with Osore-yama (on the Honshu listing), it is, along with even more volcanoes, called Yake-yama (burning mountain). There are plenty of fumarole and hot springs around the volcano… including Tamagawa spa which is apparently highly radioactive.  The onsen’s hokutolite bedrock has radium in it, which may be an effective inhibitor against one’s cancer getting worse. I can’t say it’s a cure. However, over a two to three week stay at the spa, patients lie on slabs of the hokutolite, sweating out—so it is believed—the heavy metals, toxins and carcinogens. Along with cancer, the treatment is also said to be effective against high blood pressure and circulatory maladies. And yes, radiation is used as a means to treat cancer. I have no idea why some people have a hard time knowing THAT is true. Then again, one should NEVER read the comments section under ANY on-line newspaper article for fear of discovering that there are a lot of uninformed and even racist people on this effing planet.

Asama: the most-active volcano on Honshu, and one with the longest history of documented eruptions. The complex volcano with the explosive eruptions is 2,568 meters (8,425 feet) high, and sits only 130 kilometers from Tokyo. Known eruptions are: 2015, 2009, 2008, 2004, 2003, 1990, 1983, 1982, 1982, 1973, 1965, 1961, 1958-59, 1953-55, 1952, 1952, 1950-51, 1949, 1947, 1946, 1944-45, 1938-42, 1935-37, 1934, 1934, 1933, 1931-32, 1930, 1929, 1929, 1927-28, 1924, 1922, 1920-21, 1919, 1918(?), 1917, 1916, 1915, 1914, 1909-14, 1908, 1908, 1907, 1907, 1906, 1905(?), 1904, 1903, 1902, 1902, 1900-01, 1899, 1899, 1894, 1889, 1879, 1878(?), 1875, 1869, 1815, 1803, 1803, 1783, 1779(?), 1777, 1776, 1769, 1762, 1755, 1754, 1733, 1732, 1731, 1729, 1729, 1728, 1723, 1723, 1722, 1721, 1720, 1719, 1718, 1717, 1711, 1710, 1708-09, 1706, 1704, 1703, 1669, 1661, 1661, 1660, 1659, 1658, 1657, 1656, 1655, 1653, 1652, 1651, 1650(?), 1649, 1648, 1648, 1647, 1645, 1644, 1609, 1605, 1604, 1600, 1598, 1597, 1596, 1596, 1595(?), 1591, 1590, 1532, 1528, 1527, 1518, 1427(?), 1281, 1108, 887, and 685.

Azuma: a small group of stratovolcanoes, shield volcanoes, domes and cinder cones, the volcano is considered to be restless, with increased seismic activity in 2014. The Oanu crater is currently active. Known eruptions are: 2008, 1977, 1966, ~1952, 1950, 1914, 1896, 1895, 1894, 1893, 1893, 1844, ~1800, ~1711, 1331, ~600, ~150BC, ~950BC, ~1800BC, ~2750BC, ~3000BC, ~4150BC, ~4550BC, ~5400BC, and ~5700 BC.

Bandai: one of Japan's most known active volcanoes, is an complex andesitic stratovolcano of overlapping volcanoes. The last magma was erupted at Bandai about 25,000 years ago, but during the past 5000 years, 4 major phreatic explosions have occurred at the volcano. 2 of them occurred in historical time, in 806 and 1888. In 1888, the youngest edifice of Bandai, Ko-Bandai (formed ~50,000 years ago), collapsed in a catastrophic way after a large phreatic eruption, producing a debris avalanche that buried several villages and formed several large lakes. 
The 1888 phreatic eruption and slope failure event is often referred to as Bandai-type (Bandaian) eruptions: major slope failures caused by phreatic eruptions. In contrast, Bezymianny-type eruptions (after the 1956 collapse of Bezymianny volcano in Kamchatka), include a magmatic component. Known eruptions are: 1888, ~1808, 1787, ~1767, 1719, ~1611, 806AD.

Chokai: (鳥海山, Chōkai-san) is a large stratovolcano with a broad base of 15km x 20km base, and actually consists of two overlapping volcanoes, giving it two peaks. Featuring phreatic explosions, known eruptions are: 1974, 1834, 1821, 1800-04, ~1764, 1740-47, ~1738, ~1735, 1659-63, ~1560, ~1477, ~999, ~948, 939, ~884, 871, ~861, ~857, ~856, ~839, 830, ~817, 804-06, ~717, ~711, ~610, ~577-78, ~573, ~450BC, ~650BC, ~1050BC;

Mt Fuji: Japan’s highest volcano and mountain and its most honorable symbols. Along with Tata-yama and Mount Haku, Mount Fuji is one of the Three Holy Mountains. An artist’s dream as a beautiful stratovolcano, it sits only 60 kilometers away from Tokyo at an impressive height of 3,776 meters (12,388 feet) high. Over 200,000 of people climb Mount Fuji per year to gain wisdom, which is essentially to learn that you are stupid if you climb it again. I’m paraphrasing, but that you aren’t supposed to climb it more than once. Despite all of the people climbing its flanks, Mount Fuji is not only active, but is considered ‘restless’. Known eruptions are: 1707-08, 1700, 1627(?), 1560, 1511, 1427(?), 1083, 1032, 1017(?), 999(?), 993(?), 952(?), 937(?), 932, 870, 864-65, 830, 826, 802, 800, and 781…and I’m thinking it’s long overdue. But what do I know… people eat poisonous bits of fugu because they like the fact that they could die if the chef as a bit of his game that day. There has been seismic activity in the area, but nothing closer than 15 kilometers away, and even then it was 193.9 kilometers deep in the ground.  The last eruption in 1707 is considered to be its largest ever during historical time. showering Edo/Tokyo with ash.
Hachimantai: is a long-dormant stratovolcano situated in Towada-Hachimantai National park. This volcano is a single mountain, but has multiple peaks thanks to ancient explosive eruptions. Known historic eruptions are: ~5350BC, ~7900BC.

Hakkoda: Not one, not two, but 14 stratovolcanoes and lava domes that make up this one. There are a fumaroles and hot springs around, but the dormant volcano last erupted in ~1550AD, and if you look at its previous history, it could be due for another within the next 200 years or less. Known explosive-type eruptions are: ~1550, ~1340, ~450, ~50BC, ~1150BC, ~2250BC, and ~2850BC.

Hakone: is located just 80 kilometers from Tokyo, and is a massive stratovolcano featuring two overlapping caldera—the largest is 11 kilometers x 10 kilometers wide. There are lots of lava domes and vents, with a fair bit of seismic activity in September of 2016 that was around 15 to 42 kilometers away, but in relatively shallow depth, nothing deeper than 45.4 kilometers… but nothing stronger than 3.1M.  Known eruptions are radiocarbon-dated at: ~1170 AD, ~50BC, ~1050BC, ~1200BC, ~1400BC, ~3700BC, ~6000BC.

Haku-san: is, along with Mount Fuji and Tate-yama, one of Japan’s Three Holy Mountains—all of which are actually volcanoes. A stratovolcano, Haku-san stands 2,702 meters (8,865 feet) high. Part of Haku-san National Park, known eruptions are: 1659, 1658, 1640, 1582, 1579, 1554-56, 1548, 1547, 1177, 1042, 900 (?), 859 (?), 853 (?), and 706.

Haruna: is a stratovolcano with a small summit caldera containing Lake Haruna and a cone. Despite indications that when it erupts, it is explosive, known eruptions are from around: 550, 520, and 450.

Hijiori: a caldera formed 12,000 years ago in an area where no other volcano had formed. Despite not having erupted in 12,000 years, it is considered dormant - not extinct, as scientist expect that it may—even centuries from now—erupt.  There are numerous hot springs in the area, and there has been some seismic activity recently, but no evidence of new vents.  I would call it extinct, but scientists who know better say dormant.

Hiuchi: This stratovolcano located within Nikko National Park had only one explosive eruption in 1544, with all the others being prehistoric, though the Akanagure southern dome was active 3,500 years ago with viscous lava flows. The youngest lava dome, Miike, is guessed to have been the source of the last modern era eruption.

Iwate: a dormant but active stratovolcano, it has two cones. Eruptions cause mudflows. It’s had a long modern history of eruptions: ~1934, 1919, 1732, ~1689, 1687, 1686, ~1450, ~1300, ~150, ~350BC, ~450BC, ~1150BC, ~1250BC), ~1500BC, ~1650BC, ~2000BC, ~2050BC, ~2950BC, ~3050BC, ~3250BC, ~3750BC, ~4350BC, ~4450BC, ~4850BC, ~4900BC, ~5650BC, ~6300BC, ~6450BC.

Iwaki: although dormant now, this large stratovolcano was one of the most active volcanoes in the Honshu area. The summit crater is two kilometers wide and is filled by a lava dome with size explosion craters around it. After a plethora of eruptions in the 19th century, it’s been reasonably dormant since then. Known eruptions 1863, ~1856, ~1848, 1845, 1844, ~1833, ~1807, 1800, ~1794, ~1793, 1790, ~1783, 1782-83, ~1782, ~1769, ~1709, ~1694, ~1672, 1618, ~1605, 1604, 1600, 1600, ~1597, ~1597, ~550BC, ~1050BC, ~4050BC, ~8050BC.

Izu-Tobu: is a group of volcanic vents with cinder cones, lava flows, domes and tephra deposits about 80- kilometers from Tokyo. The volcano group covers about 400 square kilometers, and includes many submerged volcanoes offshore. There are many hot springs and resorts in the area. Known eruptions are: 989, 1930 (maybe), ~1150BC, and ~2100BC.

Kanpu: although the date of its last eruption is a carbon-dated guess, it is assumed that this one-time explosive erupting volcano last went boom ~10,000 years ago. Let’s call it extinct, and if in the next 500 years it turns out I am wrong, I’ll buy everyone one points out my mistake, a Coke.

Kita Yatsuga-take: is a group of stratovolcanoes and lava domes. Last known eruption is estimated to have ben 1,200 years ago. There was a debris avalanche caused by an edifice collapse in 888AD, but otherwise, it has not been a dangerous concern.
Kurikoma: a stratovolcano with a four kilometer wide caldera that holds a lava dome, and a cone that was the site where sulfur mining occurred.  It’s dormant now, but known eruptions are: 1950, 1946, 1944, ~1783,  1744, ~1726, ~1450, ~3540BC.

Kusatsu-Shirane: is a complex of three overlapping cones and three lake-filled craters at the summit. The stratovolcano stands 2,171 meters (7,123 feet) high, and is considered to be active and restless, with all historical eruptions consisting of phreatic explosions from the acidic crater lakes and the caldera edges.  Lots of fumaroles and hotsprings around the volcano. Many of the rivers draining from the volcano are acidic. Known eruptions are: 1989, 1982-83, 1976, 1958, 1942, 1939, 1938(maybe), 1937, 1934, 1933(maybe), 1932, 1927, 1925, 1905, 1903(?), 1902, 1900, 1897, 1882, and 1805.

Megata: Of the three small maars (explosion craters) that make up this volcano, Ichinomegata is the largest and oldest at 600 meters in diameter. Ninomegat and Sannomegata (the names mean, one, two and three megata) are the others. (I'm just looking for filler material here.) Known explosive volcanic eruptions are: ~2050BC and ~7050BC.

Mutsu-Hiuchi-dake: is an extinct stratovolcano that was active 50,000 to 700,000 years ago. However, there is still fumarolic activity (hot sulfurous gas vented), which means it’s not dead yet.

Myoko: is a steep stratovolcano north of Nagano-shi, with a summit formed by a lava dome inside a three-kilometer wide caldera. No recent eruptions are known, but there are a couple from ~2360BC and ~3850BC. There has been a fair bit of seismic activity in the general area this September and October with quakes measuring between 2.5M to 3.1M. Considered dormant.

Nantai: is a stratovolcano located in Nikko National Park - been there, seen that! Apparently  the famous Lake Chuzengi-ko was formed after lava flow from an eruption blocked the Daiya River… part of that lava flow is what Kegon waterfall tumbles over. Cool! I didn’t know that before. Despite not having erupted in ~7,000 years, it is still an active volcano. There has been some seismic activity relatively close to it. Known eruptions are ~5,000BC and 12-13,000 years ago.

Narugo: another volcano that is now just a erratic 5.5 km x 7km-wide caldera. There is only one known eruption in 837. Within the caldera is Katanuma lake, with a measured ph acid of 1.6.  Prehistoric eruptions from 45,000 to 73,000 years ago helped ‘form’ the current caldera. Considered dormant.

Nasu: this volcano is actually a group of three larger and older and three  smaller and younger stratovolcanoes. This is in my neck of the woods when I lived in Japan, and I have climbed it a few times. The three young cones are: Asahi-dake, Futamata-yama, and Chausu-dake, with the latter being the youngest having only started to grow 16,000 years ago. Known phreatic eruptions are: 1963, 1960, 1953, 1881, 1846, 1410, 1408, 1404, 1397.

Mt. Nasu - climbed it and accidentally got too close to a hot steam vent. You don't want to do that!

Nikko-Shirane: is a small andestic volcano with four lava domes, and is located in Nikko National Park in Tochigi-ken, meaning I’ve probably seen it. Considered dormant at the moment, there have ben a couple of 2.5M earthquakes in the general area in early September of 2016. Known eruptions are: 1890, 1889, 1873, 1872, 1871(?), 1649, and 1625.

Niigata-Yake-yama: is another volcano on this list named yake-yama (burning mountain). This one is a very young (volcanically-speaking) andesitic-to-dacitic lava dome. This sucker is active, with lots of seismic activity through September and early October of 2016 in the area, as well as sporadic explosions as late as May of 2016. Is it due to erupt? Known eruptions are 1998, 1997, 1989, 1987, 1983, 1974, 1963, 1962, 1949, 1854, 1852, 1773, 1361, 989, 887.

Norikura: is the third-highest volcano in Japan at 3,026 meters (9,928 feet) high. It consists of a bunch of stratovolcanoes and craters, with the last eruption occurring ~2,000 years ago. Some mild seismic activity in September of 2016.

Numazawa: a long dormant volcano, it was once—according to geologic evidence—a pretty darn highly explosive volcano, but the most recent eruption occurred ~2980BC. It has a small 1.5 kilometers x 2 kilometer wide caldera that was formed during its last eruption.

Oki-Dogo: a complex of shield volcanoes forming small islands, and while most of the volcanic activity that formed it took place between 300-800,000 years ago, there is a belief that the last eruption may have occurred less than 10,000 years ago, and thus is considered active, but dormant.

Omanago: is made up of five lava domes in Nikko National park, the highest of which is 2,367 meters high. There are no known modern eruptions on record, but with the last lava dome measured to be about 5,000 years old, it is still considered to be active. That and the four nearby earthquakes of minor inconsequence.

Onikobe: is now just a caldera, as the extinct volcano last erupted about 200,000 years ago. But how extinct is it? There are a lot of hot springs and geysers in the area.

Ontake-san: is a huge stratovolcano, and is the second-highest volcano in Japan at 3,063 meters (10,049 feet) high.  Known eruptions are: 014, 2007, 1979-80, and 774, and with seismic activity in September and October of 2016 reaching 3.8M, it is considered to be restless. It is one of Japan’s holy mountains, and since 1792, pilgrims have been walking up its trails.

Osore-yama: though dormant with no known eruption since 1787, the stratovolcano is considered active, as there have been earthquake swarms noted in the late 20th century. Magma pool have also been detected under the volcano.

Sanbe: a complex stratovolcano with a small one kilometer diameter caldera. There are many hotsprings in the area of Sanbe volcano, which is part of Daisen-Oki National Park. Known eruption is ~650AD.

Shiga: despite its name, it is not near Shiga-ken, but is in fact in Gunma-ken. It is a shield volcano, rising up 2,041 meters (6,696 feet) high, and since there is no evidence of an eruption in the past 10,000 years, Shiga can be considered extinct. It is believed that the last eruptions were some 10,000 years and 250,000 years ago. There have been two seismic events in September of 2016, but in this case it seems to not be related to the Shiga volcano.

Takahara: a small stratovolcano near Tochigi-ken’s capital city of Utsunomiya, that is soooooo dormant, not having erupted in ~6,500 years. It has a few lava domes in the caldera named Shiobara. This caldera was formed 10,000 years ago and matches the Ohtawara pumice-flow deposit. Ohtawara was my home town. If there was a flow deposit there, it was never pointed out to me… dammit.

Tate-yama: is a 2,621 meter (8,599-foot) high dormant volcano that is known to have erupted in about 1858 and 1839. Along with Mount Haku and Mount Fuji, Tate-yama is one of Japan’s Three Holy Mountains.

Towada: is a collapsed stratovolcano with an 11-kilometer wide caldera that houses Lake Towada, the largest such caldera lake in Japan. The lake was formed via six big eruptions between 53,000 and 13,000 years ago. Aside from the prehistoric eruption as early as 2-million years ago, there is only one known eruption in 915, with ashfall and pyroclastic flow.

Washiba-Kumonotaira: a volcano that is part of a group of small shield volcanoes and lava domes in Chubu Sangaku National park. Because the last activity for it was 12,000 years ago, it should be considered extinct. Some consider it to be dormant, however, as I guess radiocarbon dating old flows isn’t an exact science. 

Yake-dake: is a stratovolcano standing 2,455 meters (8,054 feet) high, and is one of many volcanoes named ‘yake-dake’ which means burning peak or burning mountain. A small hydrothermal explosion in a hydrothermal area killed two people on February 11, 1995 at a highway construction site. Known eruptions are 1995, 1962-63, 1939, 1935, 1932, 1931, 1930, 1929, 1927, 1927, 1924-26, 1923, 1922, 1921, 1920, 1919, 1918, 1917, 1916, 1915, 1913, 1912, 1911, 1910, 1907-09, 1585, and 686. There has been a bit of seismic activity in the area, with the weakest being 2.7M up to 3.7M, and only eight kilometers away… but deep… very deep down.

Zao: one of the most active volcano chains in the Honshu north, Zao is a group of stratovolcanoes with the Goshi-sake summit the most active volcano of the group since eruptions were first recorded in the area in the 8th century AD.Eruptions have been explosive and phreatic (steam). Known eruptions are: 940, ~1939, ~1927, 1905, ~1897, 1896, 1895, 1895, 1894, ~1890, 1873, 1867, 1833, 1831, 1830, 1822, 1821, 1809, 1806, 1804, 1796, 1794, 1694, 1670, 1669, 1668, 1641, 1630, 1623-24, 1622, 1620, ~1400, ~1350, ~1331-33, 1230, 1227, 1183, 884, ~773, ~1600BC, ~2300BC ~2600BC, ~3350BC, ~3850BC, ~4150BC, ~5500BC, ~5600BC, ~7600BC.

Kyushu (9 volcanoes): 

Yeah - this map only shows seven... but there are nine volcanoes in Kushu.
Aso: pronounced 'ah-so' - the stereotypical phrase westerners would utter when trying to impersonate a Japanese person never seen in real life,  this volcano is one of the world's most active volcanoes, with plenty of recent ash eruptions. The volcano isn't a single volcano with one opening, rather it contains a complex of active vents within its large 24 kilometer wide caldera. Known eruptions are:  2014-15, 2011 (May), 2005, 2004, 2003, 1994-95, 1992-93, 1989-91, 1988, 1984-85, 1983, 1981, 1980, 1979-80, 1977-78, 1975-76, 1973-75, 1970-72, 1967-69, 1964-66, 1964, 1963-64, 1963, 1960-62, 1960, 1959, 1957-58, 1957, 1956, 1955, 1954, 1953, ~1952, 1951, 1950-51, 1949, 1948, 1947, 1946, 1945, 1943-44, 1943, ~1942, 1940-41, 1938-39, 1937, 1936, 1935, 1934, 1932-33, ~1931, 1930, 1928-29, 1926-28, 1925, 1923, 1920, 1919, 1918, 1916, 1914, 1911-12, 1910, 1909, 1908, 1907, 1906, 1898-99, 1897, 1894, 1884, 1874, 1872-73, 1856, 1854, 1838, 1837, 1835, 1830-32, 1830, 1829, 1828, 1827-28, 1827, 1826, 1816, 1815, 1814, 1806, 1804, 1781-88, 1772-80, 1765, ~1753-54, 1709, ~1708, 1691, 1683, 1675, 1671, 1668-69, 1668, 1649, 1637, 1631, 1620, 1613, 1612, 1611, 1598-99, 1592, 1587, 1584, 1583, 1582, 1576, 1564, ~1563, 1562, 1558-59, 1542, 1533, 1522, 1506, 1505, 1485, 1473-74, 1438, 1434, ~1390, ~1388, 1387, 1377, 1376, 1375-76, 1369, 1346, 1343, 1340, 1335, 1331-33, 1331, 1324, 1305, 1286, 1281, 1274, 1273, 1272, 1272, 1271, 1269, 1265, 1240, 1239, 1229, ~986, 867, 864, ~796, and 553. Lots of seismic activity this past September 2016.
The acidic caldera of Asu volcano.
Fukue-jima: The now-dormant volcano is a group of basaltic shield volcanoes and cinder cones that are 900,000 years old and last erupted about 2-3000 years ago.  

Ibusuku: a group of calderas, central cones and maars. It has a 4.5-km-wide caldera that formed about 4,600 years ago/ Known eruptions are: ~1615, 885, ~882, 874, ~866, ~860, ~770, ~720, ~660, ~600, ~550, ~270, ~150, ~130, and ~30AD. Lots of nearby hot springs, including the beach area nearby which is famous for its 'sand bathing'.

Kirishima: one of Japan's most active volcanoes, it is actually a group of 18 young, small stratovolcanoes. Since 742 and there are more than 60 recorded eruptions, mainly from Ohachi and Shinmoedake, with the exception of a small lava flow from Iwoyama in 1768. Known eruptions:  2011, 2008, 1992, 1979, 1971, 1959, ~1946, 1923, 1914, 1913-14, 1903, 1899-1900, 1898, 1898, 1897, 1896, 1895-96, 1894, 1891, 1889, 1888, 1887, 1880, 1832, 1822, 1771-72, 1769, 1768, 1719, 1717, 1716-17, 1716, 1706, 1690, 1678, 1677, ~1667, 1662-64, 1659-61, 1637-38, 1628, 1620, 1615-18, 1613-14, 1598-1600, 1596?, 1595, 1588, 1587, 1585, 1576-78, 1574, 1566, 1566, 1554, 1524, 1381, 1235, 1184, ~1175, 1167, 1113, 1112, 945, 858, 857, 843-48, 837-39, 788, and 742AD. A large 3.4M earthquake shook the surrounding area in early October of 2016, with increased degassing occurring at Iwo crater in February of 2016.

Kuju: the explosive volcano is actually a group of active stratovolcanoes and lava domes, that erupt as phreatic or hydrothermal explosions caused by overheated ground water. The whole volcano consists of 16 andesitic lava domes, five andesitic stratovolcanoes, and one basaltic cone.The area that makes up the volcano has lots of hot springs and hydrothermal fields, and even two geothermal power plants. A fumarole field there was mined for sulfur for over 500 years. Known eruptions are: 1995-96, ~1738, 1675, 1662, and ~370AD.

Sakurajima: ahhh... been there, seen that... and yet when I visited the area, the very active volcano was strangely quiet. It is one of the most active volcanoes in the world, and one of the few that are now in constant activity, with there typically acting with as strong strombolian to large ash explosions every four to 24 hours. And, like I said, it was quiet when I was near there. This explosive erupting volcano has been in constant eruption stage since 1955. Known eruptions are: 1955-ongoing, ~1954, 1950, 1948, 1946, 1942, 1941, 1940, 1939, 1938, 1935, 1914-15, ~1899, 1860, 1799, 1797, 1794, 1792, 1791, 1790, 1785, 1783, 1782, 1779-81, 1756, 1749, 1742, 1706, 1678, ~1670, 1642, 1478, 1471-76, 1468, 778, 766, 764, 716-18, ~712, and 708.
Sakurajima's lightning during a volcanic eruption.

Sumiyoshi-ike: is probably extinct, but is still officially dormant. The volcano is actually two maars some two kilometers apart. Last known eruptions: 4550 BC, 5050 BC.

Tsurumi: a volcano made up of a group of lava domes near Beppu on the island of Honshu - a place I visited and thoroughly enjoyed.The two main features are the Tsurumi dome (1,374 meters high) and Yufu (1.584 meters high). Considered dormant, the volcano has not erupted much in modern times, with known eruptions occurring in:  867, 771, and ~200BC.

Unzen: is now considered one of Japan's most active and dangerous volcanoes with lots of seismic activity in recent months (2016). Unzen is a group of several overlapping active stratovolcanoes (including Kinugasa on the north, Fugen-dake at the east-center, and Kusenbu on the south). In 1991, Unzen woke up from its 200-year slumber and started to extrude a new lava dome at the summit. The eruption quickly intensified, and in June, repeated collapses of the new lava dome generated pyroclastic flows that swept down its slopes at speeds as high as 200 kilometers per hour. The largest flow occurred on June 3, 1991 and killed 43 people caught by surprise by the unusually strong flow. Unzen is infamous for Japan's greatest volcanic disaster, in 1792,when a month after lava stopped erupting from the volcano, a landslide from nearby Mount Mayuyama swept through ancient Shimabara City, entered the sea, and generated a tsunami that struck nearby areas. More than 15,000 people were killed by the landslide and tsunami.

Izu Islands (17 volcanoes):

Aoga-shima: (青ヶ島) is a stratovolcano forming a small 2.5 kilometer x 3.5 kilometer island with steep cliffs in the Izu island chain, 300 km south of Tokyo. It has a 1.7 x 1.5 km diameter caldera, containing two cones. It has produced pyroclastic flows and lava flows from both summit and flank vents. Known eruptions are: 1781-85, 1670-80, 1652, ~600BC, ~1100BC, ~1200BC, ~1800BC.

Bayonnaise Rocks: (ベヨネース列岩 Beyonēsu-retsugan) is an active submarine volcano in the Izu Islands ca. 400 km south of Tokyo. The volcano has a large 8-9 km wide caldera whose highest point forms a few rocks rising just above sea level. The volcano is known for its submarine eruptions which sometimes produce temporary islands. Known eruptions, okay, most are kind of guesses: 1988(?), 1987(?), 1986(?), 1983(?), 1980(?), 1979(?), 1971(?), 1970, 1960, 1959, 1958, 1957, 1955, 1954, 1952-53, 1946, 1934, 1915, 1906,  and 1896. The 1952 blast destroyed a Japanese research ship killing all 31 people aboard. As for the weird name? It was discovered by a French ship (a corvette) called the Bayonnaise in 1846.
Bayonnaise Rocks - really.. this is it.

Doyo: is a seamount (submerged) volcano that rises 2,340 meters from the sea floor to 860 meters of the surface. It has a large horseshoe-shaped caldera measuring 3 kilometers x 10 kilometers. Hydrothermal activity was spotted in 1990 causing the volcano to be reclassified as active.

Hachijo-jima: (八丈島) consists of 14 km NW-SE elongated island in the central Izu Islands, made up of two overlapping stratovolcanoes. The last eruptions were from the Nishi-yama volcano, with earlier one—Higashi-yama—being more prehistoric in its devastation. Known eruptions are: 1707 (they think), 1606, 1605, 1518-23, 1487.

Kozu-shima: (神津島)  - makes up a 6 kilometer x 4 kilometer island consisting of 18 lava domes. It has been dormant for about 1,200 years. Known eruptions are: 838, ~832, ~100BC, ~750BC, ~8050 BC. 

Kurose Hole: a submarine circular caldera located between Mikurajima and Hachijojima in the Izu Islands. Its caldera is deep and 5 to 7 kilometers wide. There has been some seismic activity of 2.8M to 3.4M since September of 2016, and while it is known that the caldera is young (relatively speaking), when it last erupted is unknown.

Mikura-jima: (御蔵島) forms a small steep-sided island (500 meter high cliffs on two sides) that has a small population. It contains a stratovolcano and some lava domes on the SE part of the island. It last erupted in ~4100BC, and despite some nearby earthquakes, is dormant with little expectation of future eruptions.

Miyake-shima: (三宅島 ) is an active stratovolcano about 200 kilometers south of Tokyo. It consists of an 8 kilometer island, usually erupting every 10 to 30 years. There has been some minor seismic activity in October of 2016. Known eruptions are: 2010 (April-July), 2009 (April), 2008 (May), 2008 (Jan), 2006 (Aug), 2006 (Feb), 2005, 2000-04, 1983, 1962, 1940, 1874, 1835, 1811, 1763-69, 1712-14, 1709, 1643, 1595, 1535, 1469, 1154, and 1085.

Mokuyo: a seamount (below-sea) volcano with a submerged caldera rising up to 1,780 meters from the sea floor to within 920 meters of the sea surface. Its caldera is 3 kilometers x 3.2 kilometers wide and about 450 meters deep. It has a 180 meter high lava dome. Hydrothermal activity was spotted in 1990 causing the volcano to be reclassified as active.

Myojin Knoll: a large below the water volcano with pretty much just the caldera above. The caldera is six to seven kilometers wide, and 900 meters steep. It is not known when the volcano last erupted, but speculation is that the caldera was formed a few thousand years ago. It’s considered dormant.

Nii-jima: (新島) consists of eight lava domes on the island of Niijima. While there have been recorded earthquake swarms in the 20th century, and some seismic activity of 2.5M to 3.0M in September of 2016, it has not had any eruptions historically except for 886 and 840AD.

Oshima: (伊豆大島 Izu-ōshima) is the northernmost of the Izu islands of Japan, and one of the world's most active volcanoes. It is a mostly submerged stratovolcano forming an 11 kilometer x 13 kilometer island. This is one of the most active volcanoes in the world, erupting every one to three years—however, it hasn’t erupted since 1990… so… uh-oh. It has a strombolian-type of eruption with fast lava flows, lava fountains (exactly what it sounds like), and forms lava lakes. Known eruptions are: 1990, 1987-88, 1986, 1974, 1971, 1970, 1970, 1969, 1968, 1968, 1967, 1965-66, 1962-65, 1961(?), 1959-60, 1959, 1958, 1957, 1956, 1956(?), 1953-54, 1950-51, 1940, 1939, 1939, 1938, 1937, 1935, 1934, 1934(?), 1933, 1928, 1922-23, ~1920, 1919, 1915, 1914, 1912-13, 1910, 1876-77, 1870, 1868?, 1846, 1837-38, 1827, 1822-24, 1803, 1792, 1789, 1783-86, 1777-79, 1695, 1684-90, 1636-38, 1612-13, 1600-01, 1588, 1552, 1527, 1442, 1421, 1416, 1415, 1338, 1267, 1112, 936, 886, ~854, 751, ~684, ~681, ~680, 654, 630, and 605AD.

Smith Rock: Out alone in the water, the volcano is also known as Sumisu-jima and Smith Island. It’s a steep, 136 m high pinnacle rising vertically above the sea surface. There have been numerous submarine eruptions, though the last one was in 1916. However, there have been changes in the sea water color around it since the 1970s, so something is up. Known eruptions are: 1916, 1873(?), 1871, 1870, 1870, 1869, and 1672.
Sumisu-jima volcano - beautiful... now.
Sofugan: a steep volcano that sits mostly below the sea surface, rising 99 meters up above it. While there are no known eruptions, because some discolored sea water was discovered in 1975, the volcano was reclassified as active.  

Suiyo: is an active submarine volcano, whose caldera and lava dome rises some 1,400 meters above the sea floor to within 1,418 meters of the surface. Its caldera is 1.5 kilometers wide and 500 meters deep. Hydrothermal activity was observed in 1991, with temperatures reaching around 290C, prompting the reclassification of it to active.

Tori-shima: (鳥島, Torishima or Izu-no-Torishima) is a 2.7 kilometer wide island consisting solely of the stratovolcano. Along with eruptions from the summit, there have been eruptions from the submarine vents. There are a few other island volcanoes called Tori-shim (bird island). Known eruptions are: 2002, 1975, 1965, 1939, 1902, and 1871.

To-shima: (利島) is a stratovolcano forming a 2 kilometer x 2.4 kilometer island south of Oshima volcano. Its sides are steep, rising up to 300 meters on each side, with, of course, the village of Toshima located on the more gently-sloping north side. Although it hasn’t erupted since somewhere between 5,000 to 9,000 years ago, it has had some seismic activity around it this past September 2016 of 2.5M to 3.0M.

Ryukyu Islands (10 volcanoes):

Akuseki-jima: is a stratovolcano forming the entire island of the same name measuring 2.5 kilometers x 3.2 kilometers. Approximately 80 people live on this island, that relies on rainwater for water. One ferry travels 11 hours from Kagoshima, twice a week. As near as anyone can tell, the volcano last erupted less than 80,000 years ago, so it is extinct… but maybe it’s not. There has been some seismic activity in the area.

Iriomote-jima: is a shallow-depth submarine volcano about 25 kilometers from an island of the same name, and is actually on;y 200 kilometers east of Taiwan. It is estimated that it’s height is -200 meters (-656 feet) high. It’s only known activity was the October 31, 1924 eruption which is considered to be one of the largest submarine eruptions ever in Japan, spewing up a cubic kilometer of pumice that formed large rafts on the water, which later drifted some 2,000 kilometers to Hokkaido.

Iwo-Tori-shima: (aka Okinawa-tori-shima) forms a small one x two kilometer island that is active. Known eruptions of the 212 meter (696 foot) high volcano are: 2013, 1968, 1967, 1959, 1903, 1868, 1855, 1829, 1796, and 1664. On May 26, 2016, a scant 44 kilometers away and just 10 kilometers below the surface,  a 5.6 earthquake hit.

Kikai: Mostly submerged, part of the caldera does breach the surface. It is considered to be one of Japan’s most active and most explosive volcanoes. It is postulated that the Kikai volcano’s eruption some 6,300 years ago was one of the largest in the past 10,000 years, leaving the present-day caldera. Known eruptions are: 2013, 2004, 2003, 2002, 2000-01, 2000, 1998-99, 1997, 1988, 1934-35, ~1914,  ~1430, ~1340, ~1030, ~1010, ~750, ~390, ~280BC, ~1090BC, ~1830BC, ~2450BC, ~3250BC, ~3250BC, and ~4350BC.

Kogaja-jima: is a “probably” extinct volcano that makes up a small island. While there was a strong 4.6M shaker about 33 kilometers away in September of 2016, there have been no eruptions. There are a few weak fumaroles around the coastal cliffs.

Kuchinoerabu-jima: (口永良部島 本村西) is an active volcano, consisting of a sparsely-populated 4 kilometer x 12 kilometer island. There are a pair of openings, with all historic eruptions coming from Shin-take, except there is evidence of a young, but undated lava flow emanating from the older Furu-take.  Known eruptions are: 2015, 2014, 1980, 1976, 1974, 1973, 1972, 1968-69, 1966, 1945, 1933-34, 1932 (?), 1931, 1914, 1906-07 (?), 1841, 1840; ~1560, ~1470, ~1440, ~1110, ~1100, ~970, ~600, ~1140BC, ~1450BC, ~3480BC, and ~9520BC. Despite the most recent eruption in 2015, it was heard, not sen. The island was evacuated previously, and there was cloud cover—but seismic stations picked up the erupting explosion.

Kuchino-shima: dormant, this volcano is a 3 kilometer x 7 kilometer wide island consisting of two stratovolcanoes and a chain of lava domes. There are two small villages (why can’t there just be one?), but there’s no danger as the last known eruption occurred in ~1190.

Nakano-shima: is a stratovolcano out in the water forming a 9 kilometer x 5 kilometer island surrounded by coral reefs, and is considered to be active. It’s not certain, but there may have been an eruption in 1949 because it was smoking, and in 1914 there were definite phreatic explosions.  

Suwanose-jima: is considered to be one of the world’s most active volcanoes., with continuous activity since 1949, with intermittent strombolian-like activity since 2004. Known eruptions are: 2000 - to 2004 strombolian, 1999, 1996-1997, 1949-96, 1940, 1938, 1934 (?), 1925, 1921-22, 1915 (?), 1914 (?), 1889, 1885, 1884, 1877, 1813-14 (sub-plinian Bunka eruption), and ~1600 (large explosive eruption). The volcano is part of the eight kilometer long island of the same name that has, believe it or not, approx. 50 residents. I mean, come on… it’s ben active since 1949. Not that tall, it is only 779 meters (2,621 feet) high.

Yokoate-jima: is also the 3.5 kilometer long island of the same name. As far as we know, the last and only historic eruption occurred around 1835.  This stratovolcano is only 495 meters (1,624 feet) high.

Volcano Islands (15 volcanoes):

Daikoku: is a submarine volcano that rises up to within 323 meters (1,060 feet) of the water’s surface. It possesses a crater with a pool of black liquid sulfur in it that was discovered in 2006. The crater is steep-walled and is 50 meters wide and sits 75 meters below the summit. It has been seen hydrothermal fluid. It’s only known and confirmed eruption is December of 2014.  

Fukujin: is considered to be one of the largest seamounts, sometimes rising up above the waters during eruptions when it forms temporary islands.  At its highest, it is usually 217 meters (712 feet) below the water’s surface, implying that it grows during an eruption and then collapses back down to a manageable height below the water’s surface.

Fukutoku-Okanoba: a submarine volcano near Minami Iwo-jima island. It is just 14 meters (46 feet) from the water’s surface. It is suspected that this volcano more than likely built up and created Minami Iwo-jima island during its eruptions, as it has also built up several temporary ones. The first observation of a new island being build occurred in 1904-05 when the volcano spat up material to create Shin Iwo-jima (New Sulfur Island). Known eruptions are: 2010, 2005-07, 1995(?), 1993(?), 1992, 1991(?), 1987(?), 1986, 1976(?), 1974, 1973, 1972(?), 1968(?), 1967(?), 1963(?), 1962(?), 1960(?), 1959(?), 1958(?), 1956(?), 1955(?), 1954(?), 1953(?), 1952(?), 1950(?), 1914, and 1904-05.

Iwo-jima: (aka Ioto), this volcano-island is a triangular-shaped, flat, 8 kilometers long and up to 4.5 kilometers wide. It has steep cliffs down into the sea, which makes up a 9 kilometer submarine caldera. It’s about 1,250 kilometers south of Tokyo. Part of the caldera has been growing some one meter per year in parts, with an average of 25 centimeters per year over several centuries. Lots of strong hydrothermal activity present with lots of fumaroles.  This is indeed the famous/infamous island that housed such brutal battles at the end of WWII. Known eruptions are: 2012, 2001, 1982, 1980, 1978, 1976, 1974 (?), 1969 (?), 1967, 1957, and 1943. No seismic activity.
Beach eruption on Iwo-Jima, 2001.
Kaikata: is a submerged volcano (seamount) that rises up 2350 meters from the sea floor to within 162 meters of the surface. It has two major summit peaks. Although there had been no known eruptions of the volcano that was classified extinct, hydrothermal activity in 1998 had it reclassified as active, but dormant.

Kaitoku: is a large active seamount (underwater volcano) composed of three overlapping submerged volcanoes 130 kilometers northwest of Iwo-jima Island. Its three peaks are 13-18 kilometers apart and reach depths of 103 meters, 353 meters and 506 meters.Known eruptions are: ~1986, 1984, and 1543.

Kasuga: A submarine volcano that rises from three kilometers from the ocean floor to 598 meters (1,962 feet) below the water’s surface. Because of its depth, there is only guesswork to its eruptions, but floating pumice was spotted near it in 1975 and 1959.

Kita-Fukutokutai: is a recently recognized submerged and active volcano located between Iwo-jima and Minami Iwo-jima islands, rising up to just 73 meters (239 feet) below the water’s surface. because of colored water being reported over the years, along with an eruption column, it’s best guesses as to known eruptions: 2001 (?), 1988 (?), 1959 (?), 1953, 1947 (?), 1937 (?). 

Kita-Iwo-jima: (北硫黄島, officially Kita-iōtō, but also known as Kita-iōjima which means "north sulfur island". It is a steep-sided basaltic stratovolcano forming a small island. While the main caldera is not known to have erupted, the volcano's vents have spewed. Known eruptions from there are: 1953(?), 1930-45, 1880-89, and 178AD.

Minami-Hiyoshi: a submarine (submerged) volcano that comes up to within 30 meters (90 feet) of the water’s surface. Excluding 1975 when the first explosions were reported, all other dates report water discoloration implying an eruption. Known eruptions are: 1996(?), 1992(?), 1978(?), 1976(?)-77, 1976(?), and 1975.

Minami Kasuga: a submarine volcano it rise up three kilometers from the ocean floor to within 170 meters, but usually 274 meters (89 feet) of the water’s surface. There have been no historical sightings or evidence of eruptions, but it is suspected that it last erupted sometime within the past 1,000 years. It’s above my pay grade to know why that is. For the record, I don’t get paid to do this blog.

Nikko: a large submarine (submerged) volcano that is 391 meters (1,283 feet) at its highest below the water’s surface. It does rise up from a surface of three kilometers down, however. The only evidence of volcanic eruption is water discoloration, which has been spotted annually (almost) between 1979 and 1990.

Nishino-shima: (西之島, Western Island, aka Rosario Island) is a 700 meter wide island/volcano. When the volcano erupted in 1974, the ensuing explosive eruption caused several smaller nearby islands to become one. Known eruptions are: 2013-15, 1985(?), 1982(?), 1980(?), 1978(?), 1975(?), 1973-74. The questions marks are there because of the remoteness of the volcano, as well as the fact that most of it is below the water, with the island essentially its caldera.

NW Eifuku: is a submarine volcano that has all its activity below the water’s surface, with thermal activity and white smokers photographed at 1,535 meters (5,036 feet) below the water’s surface.
White smokers of NW Eifuku circa 2006. Image courtesy of from the Submarine Ring of Fire 2006 Exploration, NOAA Vents Program.
unnamed: It is unnamed because no one has seen this submerged volcano, and suspicions of its existence abound merely because water discoloration was once spotted in March of 1974. Water depth in this area is about 3,200 meters... so, if a volcano exists, it could be at quite a depth below the waves.

Okay... that's it... holy craparonie... I think I've had my fill of volcanoes for a while.

Andrew Joseph

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