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Encyclopedia > Last eruption

Last eruption refers to the last volcanic event of a volcano. The date of last eruption determines the classification of the type of volcano. A volcano is a geological landform (usually a mountain) where magma (rock of the earths interior made molten or liquid by high pressure and temperature) erupts through the surface of the planet. ...

If the last eruption occurred in historic times (i.e., a period where there is a recorded history of events), then a volcano is classified as "active." If the last eruption was pre-historic (that is, before recorded history) and within 10,000 years, then the volcano is classified as "dormant". If the last erruption was more than 10,000 years ago, the volcano is classified as "extinct."

The classification based upon "last eruption" is somewhat arbitrary. The terms used ("active", "dormant" and "extinct") imply more than their technical meaning with respect to volcanoes. For example, Yellowstone National Park is on the site of a huge volcano that erupted 600,000 years ago. Therefore, it classified as "extinct." However, there is evidence that the Yellowstone volcano erupted three times at 600,000 year intervals. Further, the hotspot (a rising plume of hot material within the Earth) is still present. This suggests that the Yellowstone volcano is far from "extinct". Yellowstone National Park is a U.S. National Park located in the states of Idaho, Montana, and Wyoming. ...



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