Mount Shirane

Japanese: 白根山 - しらねさん

A stratovolcano on the border between Gunma and Nagano prefectures. It is an active volcano that is constantly under observation. Its elevation is 2160m. It is also called Kusatsu-Shirane, to distinguish it from Nikko-Shirane (→ Mt. Shirane) on the border between Tochigi and Gunma prefectures, and Kai-Shirane (→ Mt. Shirane) in the Akaishi Mountains (Southern Alps). It belongs to the Nasu volcanic belt and rises in the southwestern part of the Mikuni Mountains. It forms a twin volcano with Mt. Moto-Shirane (2171m) to the south, and is sometimes referred to as including Mt. Yone-nashi (1863m) and Mt. Yokote (2307m). The basement is made of Neogene volcanic rocks, and the mountain body is composed of pyroxene andesite and agglomerate. It experienced a phreatic explosion in Bunka 2 (1805), and has had repeated small to medium-sized eruptions since then. It has three explosion crater lakes, Karegama, Yugama, and Mizugama, and sulfur has accumulated on the bottom of the Yugama lake. It belongs to Joshinetsu Kogen National Park, and Kusatsu Onsen and Manza Onsen are located on the mountainside on the Gunma side. The Shiga-Kusatsu Road passes through the area.

Shiraneyama

A volcano on the border between Tochigi and Gunma prefectures. It is an active volcano that is constantly under observation. It is 2,578m above sea level. It is also called Oku-Shiraneyama, and is also called Nikko-Shirane, to distinguish it from Kusatsu-Shirane (→ Mt. Shirane) on the border between Gunma and Nagano prefectures, and Kai-Shirane (→ Mt. Shirane) in the Akaishi Mountains (Southern Alps). It is sometimes used as a general term for Oku-Shiraneyama, Zazen-san (2,317m), Mae-Shiraneyama (2,373m), etc. It is located at the western end of the Nikko volcanic group, and is a lava dome-type volcano made of dacite and other rocks on a bed of rhyolite that erupted in the Neogene period. It has records of eruptions in 1649 (Keian 2), 1872 (Meiji 5), 1873, and 1889. To the west are Okama, an explosion crater, and Marunuma and Suganuma, which were formed by volcanic eruptions. Shirane Gongen is located at the summit. The starting point of the climb is Yumoto Onsen. The entire area is part of Nikko National Park.

Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information

Japanese:

群馬県と長野県の境にある成層火山。活火山で，常時観測火山。標高 2160m。栃木県と群馬県の境の日光白根（→白根山），赤石山脈（南アルプス）の甲斐白根（→白根三山）と区別して，草津白根とも呼ばれる。那須火山帯に属し，三国山脈の南西部にそびえる。南方の本白根山（2171m）と双子火山を形成，ほかに米無山（1863m），横手山（2307m）を含めていう場合もある。基盤は新第三紀の火山岩類で，山体は輝石安山岩および集塊岩で構成されている。文化2（1805）年に水蒸気爆発を起こし，以降小規模から中規模の噴火を繰り返している。涸釜，湯釜，水釜の三つの爆裂火口湖をもち，湯釜の湖底には硫黄が堆積している。上信越高原国立公園に属し，群馬県側の山腹に草津温泉，万座温泉がある。志賀草津道路が通る。

白根山
しらねさん

栃木県と群馬県の県境にある火山。活火山で，常時観測火山。標高 2578m。奥白根山ともいわれ，群馬県と長野県の境にある草津白根（→白根山），赤石山脈（南アルプス）の甲斐白根（→白根三山）と区別して，日光白根とも呼ばれる。奥白根山，座禅山（2317m），前白根山（2373m）などの総称とされることもある。日光火山群の西端にあたり，新第三紀に噴出した流紋岩を基盤に，石英安山岩などからなる溶岩円頂丘型火山で，慶安2（1649）年，明治5（1872）年，1873年，1889年に噴火の記録がある。西方に爆裂火口のお釜，火山の噴出によりできた丸沼，菅沼がある。山頂に白根権現がある。湯元温泉が登山起点。一帯は日光国立公園に属する。

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