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Volcanoes
Factfile |
 Volcanoes |
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Volcanic Shapes |
Some types of volcanoes are easily recognised and some are more difficult.
Composite Volcanoes
Called "strato" or composite volcanoes by Volcanologists (scientists who study volcanoes) because they are built up of alternative layers of lava and ash and usually have steep sides. These volcanoes can eject ash, gas, pieces of rock (known as volcanic bombs) and lava over great distances due to the high levels of gas trapped within the magma and then released at the surface. These volcanoes are often located in populated areas.
Examples: Mount Etna, Sicily; Fujiyama, Japan; Krakatoa, Indonesia
Mt. Fuji - Melinda Kolk
Shield Volcanoes
These volcanoes cover large areas (often hundreds of miles across and many thousands of feet high) and are made up of only lava. This lava is alkaline and runny. On eruption, the lava flows quickly, forming wide, flat features that are spread over large areas.
Examples: The State of Hawaii is made up of individual islands that are in fact large shield volcanoes. Mauna Loa, in the Hawaiian Islands is a shield volcano and the world's largest single mountain, rising over 30,000 ft above the ocean floor.
Mauna Loa - J D Griggs
Dome Volcanoes
These volcanoes are also made from lava only. This lava is acid and very thick. As a result, the lava flows very slowly and hardens quickly to form steep-sided features.
Example: Mount St. Helens (U.S.A)
St Helens - R Forrest Hopson
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