Noun
かざん
火山のふんかもありました。
There was a volcanic eruption too.
ふじ山は火山です。いまから四十二じかんごにふんかします。
Mt. Fuji is a volcano. It will erupt in 42 hours.
きっと火山にちがいない。
I’m sure that’s a volcano.
A fire mountain is probably what you think it is: A volcano.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well. The 山 reading is ざん instead of さん because of rendaku (sequential voicing).