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Volcano Info

 
Types of Volcanoes
Cinder Cones
Shield Volcanoes
Strato Volcanoes
Lava Plains
Volcano Hazards
Different Types of Eruptions
Types of Lava


The Basic Types of Volcanoes

There are four basic forms of volcanoes, shield volcanoes, cinder cones, and strato volcanoes. Shield volcanoes, like Kilauea, tend to bulge before an eruption, and are shaped like an upturned warrior's shield. They are created by basalt, a type of lava. Strato volcanoes are more like cones, and are made out of thick viscous, pasty lava and pyroclastics. Cinder cones are like mini strato volcanoes, and are basically made by tephra falls, or ash falls, and pyroclastics. The last one is the lava field. A lava field is basically a flat field of lava.

Cinder Cones 
Cinder cone volcanoes are probably the most common volcano type. They usually aren't the central vent of a volcano, but parisitic cones. Cinder cone eruptions are usually violent, with thick, sluggish lavas. As the lava is hurled through the air it cools, creating pyroclastics and tephra. The pyroclastics form a cone like vent.

Shield Volcanoes 
Layers of basalt lava make shield volcanoes. The lava has a low level of silica, so it is not viscous. The lava instead of piling up flows freely forming a sort of shield shaped volcano.  The top of shield volcanoes usually has a caldera, or large crater. The magma chamber sometimes empties, and cannot support the mountain above and it collapses, creating a caldera.

Strato Volcanoes 
Strato volcanoes are made by thick, sluggish, viscous, andecitic lava, and rhyolithic lava. Its lava dome builds up the volcano. During a violent eruption the entire mountain could be entirely destroyed. During one such eruption, on Krakatoa, the entire island the volcano was on was nearly blown away. During eruptions, unlike shield volcanoes, the lava isn't as hot and looks more like chunky, gray toothpaste. In some cases volcanoes can be a sort of mixture of volcanoes or compound volcano. For instance Vesuvius, in Italy, has a shield volcano on its side and the main volcano is a strato volcano.

Lava Plains 
Lava plains are basically just flat fields of basaltic lava. Lava plains are the rarest volcanoes in the world. Almost never there is tephra in a lava plains eruption.

Volcano Hazards 
All volcanoes, dormant or active, can pose danger. If there is an earthquake, there could be a landslide, and the heat of the magma underneath the volcano could melt ice and trigger a mud flow, or lahar. A lava dome may even collapse creating a nuees ardentes. During an eruption there can be the above plus ash falls, lava flows, and rock bombs.

Different Types of Eruptions 
There are basically four types of volcanic eruptions, Hawaiian, Strombolian, Vulcanian, and Plinian. Hawaiian eruptions are usually quiet, and non explosive. Strombolian eruptions include pockets of gas that explode when they reach the surface. In Vulcanian eruptions the lava is as thick as tar and is almost always incredibly violent. The most violent of all, Plinian eruptions include large pyroclastic flows, nuees ardentes and almost no quiet lava.

Types of Lava 
There are four basic types of lava, rhyolite, dacite, andesite, and basalt. In all magmas there is the mineral silica, a substance that makes the magma sticky and slow moving. Basalt has the least amount of silica, and flows the fastest of all magmas. It is 53% silica. Then comes andesite, which is 63% silica. Dacite is 68%, and rhyolite is about 75% silica.


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