Saturday, November 28, 2009

Gas and viscosity



How does amount of gas and viscosity effect the shape and how explosive volcano is?

Shield volcanoes: because of the very low viscosity lava, shield volcanoes are almost always flat and has a very large surface area. their eruptio
ns are also not very violent and slow moving.


Stratovolcano or composite volcanoes: these volcanoes usually are very large and steep due to their very viscous magma. if this magma also has a high gas content then the eruption of the volcano is more violent.

Cinder cone: formed by a very low gas and low viscosity magma. these volcanoes are formed by the piling up of tephra




the reason why the gas content of the magma is so important s because it determines how much pressure is created in the magma chamber. over ti
me gas will build up and an eruption may occur, often being triggered by an earthquake




Think of a glass of water, if you blew a bubble through a straw, the bubble will make its way up and out. now imagine you have a milkshake if you did the same with that, you would probably have a face covered in chocolate. this happens because the milkshake is thicker and there is more energy required to move it, therefor a more powerful reaction.

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