The Nature of Vocanic Hazards

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The nature of volcanic hazards is often classified by the violence of the explosion and thus is assigned a number from the Volcanic Explosivity Index (VEI), for instance Icelandic and Hawaiian volcanoes which erupt basaltic lava - which has a low silica content and a basic chemical composition; it reaches a maximum temperature of 2000 degrees Celsius and thus has low viscosity. Due to this, gases are easily released and so the eruptions are non-explosive, with a VEI of 0-1 A prime example of this form is the Eyjafjallajokull volcano in Iceland which erupted in 2010, where during the fissure phase less vicious basaltic lava effusively erupted onto the surface and flowed west – it was also olivine –rich. However the explosive phase had a VEI of 4, hence classified as a large, violent eruption.
On the contrary, Vesuvian and Krakatoan forms have moderate yet explosive eruptions, they erupt andesitic lava which has high silica content and an acidic chemical composition; gases do not escape easily – thus it is viscous – so they build up to produce explosive eruptions with lower temperatures (max. 1000 degrees Celsius). Rhyolitic lava is similar, although it has lower temperatures at around 750 degrees. An example of an andesitic lava eruption is Soufriere Hills in Montserrat which has been actively erupting since 1997. The eruption in 1997 achieved a VEI of 3 (which is significant particularly due to the VEI being a logarithmic scale). Thus based on the nature of volcanic event
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