Topic summary
Dormant volcano
Extracted from the Wikipedia article Volcano.
Dormant and reactivated
The USGS defines a dormant volcano as any volcano that is not showing any signs of unrest such as earthquake swarms, ground swelling, or excessive noxious gas emissions, but which shows signs that it could yet become active again. Many dormant volcanoes have not erupted for thousands of years, but have still shown signs that they may be likely to erupt again in the future. Technically, any volcano that is dormant is also considered to be geologically "active".