Difference Between Active and Dormant Volcanoes
Written by Fraser Cain
Volcano Vesuvius. Image credit: Pastorius
Geologists classify some volcanoes as active and some volcanoes as dormant. But what do they mean? What's the difference between active and dormant volcanoes? This is actually a complicated question, because there's no way to know for sure if a volcano is all done erupting, or it's going to be active again.
An active volcano is one that's currently in a state of regular eruptions. Maybe it's going off right now, or had an event in the last few decades. And geologists expect it to erupt again very soon. A dormant volcano is one that is capable of erupting, and will probably erupt again in the future, but it hasn't had an eruption for a very long time.
And here's the problem. The lifespan of a volcano can last for thousands of years, or it can go on for millions of years, with regular eruptions. Many of Earth's volcanoes have had dozens of eruptions in the last few thousand years, but they've been quiet for recorded history, and have large populations built up around their base. The Smithsonian Global Volcanism Program defines a volcano as active if it has had an eruption within the last 10,000 years or so.
And so a dormant volcano is actually part of the active volcano classification, it's just that it's not currently erupting.
When a volcano becomes cut off from its magma supply, that's when it finally stops erupting and becomes an extinct volcano.
We have written many articles about volcanoes for Universe Today. Here's a more detailed article about active volcanoes, and here's one about dormant volcanoes.
Want more resources on the Earth? Here's a link to NASA's Human Spaceflight page, and here's NASA's Visible Earth.
We have also recorded an episode of Astronomy Cast about Earth, as part of our tour through the Solar System – Episode 51: Earth.
Filed under: Astronomy
