is a

stratovolcano A stratovolcano, also known as a composite volcano, is a typically conical volcano built up by many alternating layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with ...

located in Akan National Park in

Hokkaidō is the second-largest island of Japan and comprises the largest and northernmost prefecture, making up its own region. The Tsugaru Strait separates Hokkaidō from Honshu; the two islands are connected by railway via the Seikan Tunnel. The ...

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

Geography and geology

Mount Oakan sits in the Akan caldera northeast of

Lake Akan is a lake in Kushiro, Hokkaidō, Japan. It is located in Akan National Park and is a Ramsar Site. History Volcanic activity formed the lake some 6,000 years ago, when a lava dam was formed. The lake used to have a clarity of 8–9 meters in t ...

. The volcano rises some above the surrounding terrain. The top of the volcano is above sea level. The volcanic cone is some in diameter. There are three explosion craters at the summit. At at about , there is a

fumarole A fumarole (or fumerole) is a vent in the surface of the Earth or another rocky planet from which hot volcanic gases and vapors are emitted, without any accompanying liquids or solids. Fumaroles are characteristic of the late stages of volcani ...

. The volcano is made mostly from non-alkali

mafic A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include ...

volcanic rock. The main rock type is

andesite Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predomina ...

and

dacite Dacite () is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides. It has a fine-grained (aphanitic) to porphyritic texture and is intermediate in composition between andesite and rhyolite. ...

History

Mount Oakan emerged in the

Late Pleistocene The Late Pleistocene is an unofficial Age (geology), age in the international geologic timescale in chronostratigraphy, also known as the Upper Pleistocene from a Stratigraphy, stratigraphic perspective. It is intended to be the fourth division ...

dropping pumice on Minamishikata. After that, continuous lava flows formed the bulk of the volcano. In the final stages of its life, a parasitic volcano formed a

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 ...

at the summit. According to its name and local legend, Mount Oakan is the male counterpart to Mount Meakan on the other side of Lake Akan.

Notes

External links

Oakandake
- Japan Meteorological Agency * - Japan Meteorological Agency

- Geological Survey of Japan
Akan: Global Volcanism Program
- Smithsonian Institution {{DEFAULTSORT:Oakan Mountains of Hokkaido Volcanoes of Hokkaido