Crater lake - Kakogenko

Japanese: 火口原湖 - かこうげんこ

A lake formed by the local accumulation of water in a flat area (crater floor) inside a caldera that develops inside the somma of a composite volcano. It occupies part of the caldera, between the caldera wall and the central crater cone. Like caldera lakes and crater lakes, the drainage area is relatively small compared to the lake surface area. As a result, the sedimentation rate is slow and the nutrient concentration in the lake water is generally low. Representative examples include Lake Haruna in Gunma Prefecture, Lake Ashinoko in Kanagawa Prefecture, and Lake Onuma on Mount Akagi in Gunma Prefecture.

[Kazunori Mori]

[References] | Crater lake | Caldera | Caldera lake | Lake

Lake Ashi
The crater lake of the Hakone volcano. The photo shows the view from Motohakone on the southeast shore. Pleasure boats run on the lake, and it is the center of Hakone tourism. On the lake shore stands the large torii gate of Hakone Shrine, and behind it you can see Mount Fuji. Hakone-machi, Ashigarashimo-gun, Kanagawa Prefecture ©Shogakukan ">

Lake Ashi

Lake Onuma
The crater lake of Mount Akagi. It is about 4km in circumference. In winter, it freezes over, so you can enjoy ice skating and ice fishing for smelt. Akagi Shrine is located on Kotori Island (center of photo) on the east shore, and Jizo-dake (right of photo), a central crater cone, rises to the south. Maebashi City, Gunma Prefecture © Maebashi Tourism and Convention Association ">

Lake Onuma

Lake Haruna
A lake in the crater basin of Mount Haruna in western Gunma Prefecture. The lake surface is 1,084m above sea level and has a circumference of 4.8km. In winter, the lake freezes over and many people come to fish for smelt. In the center of the photo is the crater cone of Mount Haruna. Takasaki City, Gunma Prefecture © Takasaki Tourism Association ">

Lake Haruna

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

Japanese:

複式火山の外輪山の内側に発達するカルデラ内の平坦(へいたん)な部分（火口原）に局所的に水をたたえて生じた湖。カルデラの一部、カルデラ壁と中央火口丘との間を占める。カルデラ湖や火口湖と同じく、湖面の面積に対し流域面積が比較的小さい。このため堆積(たいせき)速度が遅く、湖水中の栄養塩濃度は一般に低い。群馬県の榛名湖(はるなこ)、神奈川県の芦ノ湖(あしのこ)、群馬県赤城山(あかぎやま)の大沼(おの)などが代表例としてあげられる。

［森　和紀］

[参照項目] | 火口湖 | カルデラ | カルデラ湖 | 湖沼

芦ノ湖
箱根火山の火口原湖。写真は南東岸の元箱根付近からの眺望。湖上には遊覧船が走り、箱根観光の中心をなしている。湖岸には箱根神社の大鳥居が立ち、その後方には富士山が見える。神奈川県足柄下郡箱根町©Shogakukan">

芦ノ湖

大沼

榛名湖

出典　小学館　日本大百科全書(ニッポニカ)日本大百科全書(ニッポニカ)について　情報 | 凡例

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