dormant volcano

...Therefore, volcanoes from ancient geological times are more significant as sites of volcanic eruption.
[Active volcano, dormant volcano, extinct volcano]
Volcanoes are divided into (1) those currently actively active, (2) those with records of eruptions but not currently erupting and with no fumarolic or sulfuric activity, and (3) those with no records of eruptions and no current volcanic activity but recognized as volcanoes based on their shape and structure. (1) is sometimes called an active volcano, (2) a dormant volcano, and (3) an extinct volcano. This classification has been commonly used for a long time, but it is a convenient one, and there are many cases where volcanoes that were thought to be dormant or extinct have become active again.

*Some of the terminology that mentions "dormant volcano" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…したがって古い地質時代の火山は火山噴火地点としての意味が強い。
【活火山，休火山，死火山】
　火山を，(1)現在盛んに活動中のもの，(2)噴火の記録はあるが，現在は噴火もせず，噴気･硫気活動もないもの，(3)噴火の記録は残されてなく，現在も火山活動はないが，その形や構造から火山と認定されるものに分け，(1)を活火山active volcano，(2)を休火山dormant volcano，(3)を死火山extinct volcanoと呼ぶことがある。この分類は長いこと一般に使われていたが，便宜的なもので，休火山や死火山と考えられていたものが再び活動した例はいくつもある。…

※「dormant volcano」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報