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Home Up Earth's Interior Landforms Volcanoes Earthquakes

 

Effects of Volc.
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Vulcanicity is the process which magma from the Earth's interior rises into the earth's crust or is forced out onto its surface.

Magma is the molten material below the solid crust of the Earth. It is kept in a liquid state because of the high temperature and great pressure there.

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FORMATION

When a volcano erupts, magma is ejected to the surface. Lava cools and solidify, forming small fragments such as cinders and volcanic ash. Gases are also given off : steam, Carbon Dioxide and Sulphur dioxide.

Stages

Active     ---> Eruptions are frequent e.g. Mt Mayon in the Philippines

Dormant  ---> Eruption are infrquent e.g. Fujiyama in Japan

Extinct   ---> No eruptions since historic times.

 

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CALDERA
An explosive volcanic eruption may be so violent that it completely shatters the top of the volcano and it sinks into a huge crater called caldera. The caldera may be fill up to become a crater lake e.g. Lake Toba in Sumatra (Indonesia) and Crater Lake in Oregon (USA).

 HOT SPRING
In volcanic areas where water sinks deep enough to be heated by the magma, the superheated water may flow quietly out of the Earth's crust to form a hot spring (carries dissolved minerals).
Geyser
geyser is a violent ejection of hot water and steam through a vent. The steam is produced when the water boils. This jet of hot water and steam rises to great heights and occurs at intervals as there must be sufficient water and steam to produce the eruption.  ~found at National Park USA
 

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