is the name of a group of
shield volcano
A shield volcano is a type of volcano named for its low profile, resembling a warrior's shield lying on the ground. It is formed by the eruption of highly fluid (low viscosity) lava, which travels farther and forms thinner flows than the more vi ...
es located on the coast of
Japan
Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the n ...
on the southwest end of the island of
Honshū
, historically called , is the largest and most populous island of Japan. It is located south of Hokkaidō across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyūshū across the Kanmon Straits. The island sepa ...
. It is primarily based in the city of
Hagi,
Yamaguchi Prefecture
is a prefecture of Japan located in the Chūgoku region of Honshu. Yamaguchi Prefecture has a population of 1,377,631 (1 February 2018) and has a geographic area of 6,112 km2 (2,359 sq mi). Yamaguchi Prefecture borders Shimane Prefecture t ...
.
The group dates from 800,000 years ago and was active into the
Holocene
The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togeth ...
era. The last eruption occurred around 9000 years ago.
The group of volcanoes consists of
basalt
Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90 ...
and dacitic lava flows, small shield volcanoes,
cinder cone
A cinder cone (or scoria cone) is a steep conical hill of loose pyroclastic fragments, such as volcanic clinkers, volcanic ash, or scoria that has been built around a volcanic vent. The pyroclastic fragments are formed by explosive eruption ...
s, and
lava dome
In volcanology, a lava dome is a circular mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano. Dome-building eruptions are common, particularly in convergent plate boundary settings. Around 6% of eruptions ...
s. Altogether, there are about 40 volcanoes, with the highest peak being Irao-yama.
Volcanic activity in the region i related to
subduction
Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, ...
of the
Philippine Sea Plate
The Philippine Sea Plate or the Philippine Plate is a tectonic plate comprising oceanic lithosphere that lies beneath the Philippine Sea, to the east of the Philippines. Most segments of the Philippines, including northern Luzon, are part ...
.
The erupted magmas of Abu are mainly alkaline basalt and calc-alkaline andesite - dacite in composition.
See also
*
List of volcanoes in Japan
This is a list of active and extinct volcanoes in Japan. An Orange background indicates a volcano considered active by the Japan Meteorological Agency.
Hokkaido
Honshū
Izu Islands
Ogasawara Archipelago
The Ogasawara Archipelag ...
*
List of mountains in Japan
The following is a list of the mountains and hills of Japan, ordered by height.
Mountains over 1000 meters
Mountains under 1000 meters
As the generally accepted definition of a mountain (versus a hill) is 1000 m of height and 500 m of pro ...
References
External links
Abu Volcanoes- Japan Meteorological Agency
* - Japan Meteorological Agency
Abu- Smithsonian Institution: Global Volcanism Program
Volcanoes of Honshū
Volcanic fields
Volcanoes of Yamaguchi Prefecture
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