Analyse the Factors That Cause Differences in the Hazards Posed by Volcanoes Around the World.

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Analyse the factors that cause differences in the hazards posed by volcanoes around the world. (40 marks) A hazard is defined as a situation that poses threat to life, health, property or environment. However the level of hazard imposed by volcanoes can differ greatly, from a weak eruption not endangering any lives, to a violent eruption that can affect countries all over the world. There are various factors that can alter how hazardous a volcano is. The more explosive a volcano, the more hazardous it usually is. The type of magma is a huge physical factor determining the volcanoes level of explosiveness, based on the temperature, gas content and chemical components volcanologists can tell how viscous the magma is. The higher the temperature of the magma and lower the silica content the runnier it will be and therefore less explosive however, a lower temperature and higher gas content would cause a more explosive eruption as the gas wouldn’t be able to escape due to the density of the magma, high silica content would also cause more internal friction and increase explosivity. These types of eruptions are common with rhyolite rock type within the magma. However, viscous lavas are not always the most hazardous; an example of a low viscosity, destructive eruption is that of Mt. Nyiragongo in 2002. This is a strata-volcano found along the African Rift Valley at a constructive plate margin, however it did not erupt from the crater, it erupted from a 13km long fissure on the southern flank having devastating consequences. Lava flows alone destroyed a third of Goma including part of the airport runway, 14,000 homes were destroyed, 350,000 flee and 147 people were killed as 15 million cubic yards of lava cover the area. Sulphurous
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