volcanos!!

A volcano is the only conduit that puts in direct communication with the Earth's surface deep levels of the earth's crust. The word volcano was derived from the name of the mythological god Vulcan. It is the only means to observe and study the origin of magmatic lithic materials, which accounted for 80 percent of the solid crust. At the depth of the mantle, the magma under pressure rises, creating magma chamber within or below the crust. The cracks in the rocks of the crust provide an outlet for the intense pressure, and the eruption takes place. Water vapour, smoke, gases, ash and lava rocks are thrown into the atmosphere. A volcano, in essence, is a geological device, temporarily or permanently communicating between the mantle and the Earth's surface. A volcano is also a geological structure, by which emerge magma (molten rock) and gases inside a planet. The rise usually happens in episodes of violent activity called eruptions. At accumulate material drawn from the interior forms a conical structure on the surface that can reach heights few hundred metres to several kilometres. At the tube that connects the reservoir of magma or magma chamber at depth with the surface is called the chimney. This ends at the top of the volcanic edifice, which is topped by a depression or crater. Some volcanoes after suffering major eruptions, massive collapse forming depressions in their peaks exceeding kilometer in diameter. These structures are called boilers. The viscosity (fluency) from the lava thrown by volcanoes is controlled by its chemical composition. Thus, more fluid lava, or Hawaiian-type, have compositions rich in iron and magnesium and are low in silica. These out of the chimney are stored in the crater, or caldera to overflow, forming rivers of magma can flow distances of several dozen kilometers. Source of lava 10 meters high in a volcano of HawaiLas viscous lava have a high content of silica and water vapor. Given that flow poorly, forming a plug in the chimney leading to explosive eruptions, increasing the size of the crater. In extreme cases can completely destroy the building as happened during the volcanic eruption of Mount St. Helens in 1980. The lava eruption not always from a central chimney as it can make their way through openings in the flanks of the volcano. If such eruptions are ongoing can lead to what is known as cone parasite. Mount Etna has more than 200 of these parasites cones and some of them only expel gases. The latter are called fumaroles. In general volcanoes are associated with the boundaries of tectonic plates, although there are exceptions such as volcanism of hot spots or hot spots located in the interior of tectonic plates, as is the case of Hawaii Island, also Barajas theory for the origin the Canary Islands. Geologists have classified the volcanoes in three categories: a shield volcanoes, cones and ash cones compounds (also known as stratovolcanos). A volcano of paramount importance was the Paricutín in Mexico, although not large, its importance lies in what they contributed to the volcanology (1940s-50s) and that could be studied by Gerardo Murillo, "Dr. Atl" since birth until his death (his life lasting nearly a decade).



there is also Eruptions submarine In the seafloor volcanoes occur whose lava, if they reach the surface, they may form volcanic islands. These are usually of short duration in most cases, due to Isostatic balance of the lava cooled and by sea erosion.


here is a video!

http://video.google.com/videosearch?q=el+mayor+volcan+en+erupcion&hl=en&emb=0&aq=f#q=erupciones%20volcanicas&hl=en&emb=0