Extinct volcanoes have no access to a magma supply or have never erupted, such as the Hawaiian ridge. Dormant volcanoes have documented eruptions, but have not erupted recently, such as Yellowstone.
New volcanoes form every century, but usually in the same area as existing volcanoes. In 1943 a volcano growing in the middle of a flat cornfield in Mexico was discovered. Paricutin grew to 1,353 feet and erupted for nine years. Today it is 9,213 feet above sea level. In 1973 a new volcano covered the island of Heimaey in Iceland with ash and lava.
Physically, they dominate the landscape, and have an active role in shaping our planet's geography. When they are actively erupting, they are an extremely dangerous and destructive force. But when they are passive, the soil they enrich can become very fertile, leading to settlements and cities being built nearby.
As such, some volcanologists refer to extinct volcanoes as inactive, and some volcanoes once thought to be extinct are now referred to as dormant. In short, knowing if a volcano is active, dormant, or extinct is complicated and all comes down to timing. And when it comes to geological features, timing is quite difficult for us mere mortals.
Volcanoes Types Volcanoes are classified on the basis of the nature of volcanism. On the basis of the frequency of eruption, volcanoes are of three types: Active, Dormant and Extinct. (1) Active Volcano. Those volcanoes which erupt frequently or have erupted recently are termed as active Volcano.
Active, dormant or extinct? For a volcano to be classed as active, it is either erupting now, or is likely to erupt soon. According to scientists, an active volcano must have erupted during the last 10,000 years. A dormant volcano on the other hand, could be described as sleeping, because it is still active, but not currently erupting.
Is Yellowstone active dormant or extinct? Yellowstone is another “dormant” volcano, yet the level of constant unrest under Yellowstone might make it “active” by my definition. A truly dormant volcano by the USGS standards might be Clear Lake in California, which hasn’t erupted in likely close to 10,000 years.
Even dormant and extinct volcanoes are becoming active again. An extinct volcano by definition is a dead volcano, which has not erupted in the last 10 000 years and is not expected to ever erupt again. In other words, an extinct volcano implies that there is no magmatic, seismic or degassing activity going on at the volcano and that it's not.