Active, Dormant & Extinct
Compare volcano labels: active means erupting now or recently in this lesson, dormant means quiet for a long time but able to erupt again, and extinct means another eruption is not expected
What a learner can do afterwards
- Define active, dormant, and extinct using the lesson's labels
- Explain why a long quiet period does not prove that a volcano is safe from another eruption
- Use eruption history and other evidence to discuss a volcano's label, including when quiet years alone are not enough
1 · Read
A volcano stays a volcano on quiet days. Scientists call one extinct when they do not expect another eruption. If new evidence suggests it could erupt again, they review that label.
Here we use active for a volcano erupting now or recently. Dormant means quiet for a long time but still able to erupt again. Extinct means another eruption is not expected. Active does not mean an eruption will happen soon.
There is no single number of quiet years that sorts all volcanoes. A long quiet time alone cannot prove extinction. Scientists use eruption history and other evidence. Some scientists include dormant volcanoes in the active group.
Volcano B has been quiet for 700 years, but scientists think it could erupt again. Using our labels, it is dormant. Scientists do not expect Volcano C to erupt again, so they call it extinct.
A dormant volcano may erupt again, so quiet does not mean safe from eruptions. Scientists watch for changes such as earthquakes and ground movement to help judge possible danger. Monitoring cannot promise an exact eruption date or a long warning. Follow local safety advice.
Here, active means erupting now or recently. Dormant may erupt again after a long quiet time. Extinct means another eruption is not expected. Quiet years alone cannot decide the label.
Lesson, questions and flashcards written for this dataset.
Reading and flashcards written for this dataset. The Yellowstone teaching-resource catalog record informed the choice of monitoring examples; its wording is not reproduced.
More to read
Clues from a quiet volcano
Scientists do more than ask when a volcano last erupted. At Yellowstone, they keep records of earthquakes. They also measure whether the ground rises, sinks or moves sideways. Some measurements come from tools on the ground; others come from satellites.
These records are clues. A cluster of earthquakes does not by itself mean an eruption is coming. Scientists compare different clues and changes over time before explaining what they might mean.
Yellowstone is called active even when no eruption is happening. This use of active includes a quiet volcano that could erupt again. It does not mean an eruption will happen soon. Watching a volcano helps people understand possible danger, but it cannot promise an exact eruption date or a long warning. People should follow local safety advice.
2 · Watch
En anglaisTake it off screen
Where it sits
Learn first
Optional connections
This opens up
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.