1.
volcanic crater; volcanic vent
The opening at the top of a volcano (or on its flanks) from which lava, ash, and gases are ejected during an eruption. 噴火口 refers specifically to the active vent, while the broader bowl-shaped depression that may form around it is more often called 火口.
噴火口から煙が出ている。
Smoke is coming out of the crater.
噴火口の近くは立ち入り禁止になっている。
The area near the crater is off-limits.
研究者たちは噴火口から噴出するガスの成分を調べた。
The researchers analyzed the composition of the gases erupting from the volcanic vent.
大規模な噴火では、複数の噴火口が同時に活動を始めることもある。
In large-scale eruptions, multiple craters can sometimes become active simultaneously.
噴火口 is the specific term for the opening through which a volcano erupts. It is formed transparently from 噴火 ("eruption") + 口 ("opening, mouth"), with the on'yomi reading こう in this compound.
FORMATION:
- 噴火 ("eruption") + 口 ("opening") → 噴火口
COMMON COLLOCATIONS:
- 噴火口から噴出する: to be ejected from the crater
- 噴火口を覗き込む: to peer into the crater
- 活動中の噴火口: an active crater
- 新しい噴火口が開く: for a new vent to open
- 噴火口付近: the vicinity of the crater
SIMILAR / RELATED TERMS:
- 火口: crater (the broader depression at a volcano's summit; can also include extinct or dormant craters)
- 噴火: eruption (the event itself)
- 火山: volcano (the mountain as a whole)
- カルデラ: caldera (a much larger collapse-formed depression)
- 溶岩: lava
- 火砕流: pyroclastic flow
USAGE NOTES:
- 噴火口 emphasizes the active vent that ejects material; in news reports about ongoing volcanic activity, this is the term most often used.
- 火口 is more general and can refer to any volcanic crater regardless of activity. In casual speech, 火口 alone is often sufficient.
- The same kanji compound 噴火 also appears in 大噴火 ("major eruption") and 噴火警報 ("eruption warning").