Volcanoes Plate Tectonics. Contents. What is a volcano? Why do volcanoes occur? Where are volcanoes found? A case study: Mount St Helens Can eruptions be predicted? Why do people live in volcanic areas? Summary activities. The key concepts covered are: - PowerPoint PPT Presentation
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What is a volcano?Why do volcanoes occur?Where are volcanoes found?A case study: Mount St HelensCan eruptions be predicted?Why do people live in volcanic areas?Summary activities
The key concepts covered are:Place, Space and Physical and human processes.
An active volcano is liable to erupt at any time, e.g. Mt Etna.A dormant volcano has not erupted for years. Mt Pinatubo erupted in 1991 after 500 years of dormancy.
Categorizing volcanoes can be tough. Chaitén in Chile erupted in 2008 for the first time since 7400BC!
Volcano types
There are three different types of volcano. Geographers call the categories active, dormant or extinct.
An extinct volcano has not erupted for a very long time and is unlikely to erupt again, e.g. Edinburgh.
The effects of the Mount St Helens eruption were enormous. The pyroclastic surge spread 27km from the volcano and flattened acres of woodland.Ash clouds stretched 26km above sea level.
However, there were some positives.
Some plants and animals were resilient enough to survive.The lack of human interference encouraged nature to spring forth again.
Since 1980, there has been more activity on Mount St Helens.
Between 1980 and 1986 a new lava dome was formed.Magma reached the surface of the mountain in October 2004.In 2005, a 36,000 foot plume of steam was emitted. There was also a small earthquake.
It seems likely that Mount St Helens will erupt again in the future. Will we be able to tell when?