Volcanic Erruption

Volcanoes are a natural way that the Earth and other planets have of cooling off. Planets are warm in their mantles. Heat inside planets escapes towards their surfaces. For reasons that are not well understood, heat sometimes melts rocks, which then rise toward the planet's surface. When the hot rocks, called magma, and included gases, break through the crust an eruption occurs. The buildup of ash and lava flows around the eruption hole makes a volcano. Some volcanoes erupt for only a short time - a few days to weeks and never erupt again. Large volcanoes, such as stratovolcanoes and shields, erupt thousands of times throughout their lifetimes, which can last hundreds of thousands to a few million years.

There are some types of volcanoes. The first one is shield volcanoes. They are broad shielded volcanoes formed by eruptions of lava having low viscosity. Lava of these volcanoes usually don’t get explode out but it can travel a large distance with very low velocities.


The second one is lava domes. These are the volcanoes which came into origin by eruptions of lava with high viscosity. These volcanoes produce very violent and explosive eruptions. Their lava don’t travel large distances from the vent.

The third is stratovolcanoes.These are tall mountains of conical shapes, these volcanoes are composed of flowing lava and ejecta in layers, called strata. Most common example is the Mt. Fuji of Japan. These volcanoes claim most hazardous eruptions of history.

The next is super volcanoes. These volcanoes usually produce lava on very large scales. Super volcanoes eruptions cause extreme cooling of the surrounding global temperatures, because they produce a large amount of sulfur and ash clouds. This decrease in temperature lasts for many years. So they can be classified as the most dangerous volcanoes, for example- Lake Taupo of New Zealand.
 
And the last one is submarine volcanoes. These are the volcanoes which are located at the floors of oceans. They can be at lower or extreme depths. Those volcanoes which are present at lower depths produce bubbles of steam and gases, which can be observed above the sea surface. But other volcanoes which are present at extreme depths are almost invisible about their existence. But even these deep volcanoes can also be marked by observing discoloring of water at a particular portion of ocean. This discoloration is because of release of volcanic gases in the sea.

Other less common types of volcanoes are sub glacial volcanoes, Antarctica volcanoes, mud volcanoes etc.