Fire reflection

This phenomenon occurs when the clouds and smoke above a volcano appear bright red at night, reflecting the red-hot lava, flames, and red-hot lava flows in the crater. It can be seen at volcanoes that are currently erupting or in the active phase, and is a red flag for monitoring volcanic activity. Prior to the eruption of Mount Asama in 1973 (Showa 48), the Karuizawa Meteorological Observatory issued emergency volcano information based on the fire glow and the occurrence of volcanic earthquakes, which was effective in preventing disasters. On Izu Oshima, the phenomenon known as sacred fire is usually a fire glow caused by red-hot lava exposed in the crater.

[Akira Suwa]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

夜間、火山上空の雲や噴煙が、火口内の赤熱溶岩や火炎、それに赤熱溶岩流などに映え、明るく赤く染まって見える現象。噴火中ないし活動期の火山で見られ、火山活動監視上の赤信号である。1973年（昭和48）の浅間山噴火に先だち、軽井沢測候所は、火映と火山性地震の発現状況から臨時火山情報を出し、防災の実をあげた。伊豆大島で御神火(ごじんか)とよばれる現象は、たいてい、火口内に露頭した赤熱溶岩による火映である。

［諏訪　彰］

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