The number of fatalities that result from volcanic and seismic natural hazards is related to the level of development in the country in which they occur. Discuss.

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The number of fatalities that result from volcanic and seismic natural hazards is related to the level of development in the country in which they occur. Discuss.

A natural hazard is an event, linked to the physical environment, which is considered to have a negative effect on humans. The event is also seen to be unpreventable by humans. However, an event such as a volcanic eruption that has no effect on human beings is considered a natural phenomenon rather than a natural hazard. It is the presence of humans, in an area that such an event occurs, that allows it to be termed a hazard. Although humans cannot prevent these occurrences, they have a role to play in the event’s extremity as a natural hazard. For example, volcanic eruptions have been present throughout history, but it is not until settlements are built on the rich soils they form that they become a hazard. This essay I will evaluate the extent to which the level of development in a country affects the number of fatalities caused by volcanic and seismic natural hazards.

A volcanic natural hazard is a volcanic eruption. Volcanoes are formed at convergent and divergent plate boundaries and also at hot spots. At convergent plate boundaries eruptions tend to be from a vent, as oceanic crust is forced beneath another plate, the extremities of heat and pressure leads to the partial melting of the crust which is being submerged. The magma formed from oceanic crust is less dense than (due to its high water content) the mantel and rises up through the vent (this can be seen in figure 1). The lava is generally acidic and is also viscous. This means that eruptions are usually, violent and unpredictable. At divergent plate boundaries the eruptions are from a crack. The eruptions are intermittent and not very violent as the lava has a low viscosity and acidity. Hot spots are volcanic regions where the underlying mantle is thought to have a higher temperature than the surrounding magma allowing it to rise up, hot spots may form island chains are arcs. (illustrated in figure 3)

A seismic natural hazard, is most commonly thought to be an earthquake, however an earthquake can be the cause of many other natural hazards, such as tsunamis. An earthquake is a sudden release of energy in the earth’s crust creating seismic waves. Irregularities on faults that are moving past cause frictional build up, when their force against one another build to a high enough degree they lurch past one another and the pressure is released as seismic waves causing an earthquake. A similar process occurs at submergent plate margins.

Volcanic eruptions, though unpreventable, can be predicted. Prediction allows a plan of action to be formulated to protect the population of a country. To predict an eruption many factors must be take into account, seismic shockwave patterns, hazard mapping, sampling of lava and gas emissions and remote sensing of changes to the geography of the land and heat and gas emissions (these methods are illustrated in figure 4). To protect the population, actions to reduce possible damage and instruct people on what precautions are thought to be necessary must be taken. Longer term protection might involve land-use planning to minimise the impact of future hazards.

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Chile is located in South America and has a population of approximately 16,888,760. It is classed as a relatively less developed country. In 2008 on the 2nd of May a volcano in south eastern Chile erupted, called Chaiten (it’s location in relation to plat boundaries can be seen in figure 5), a caldera, one of the most explosive forms of volcano. Chaiten has formed due to the presence of the subduction zone where the Pacific plate is being forced beneath the South American continental crust (this process can be seen in the simplified diagram in figure 6). The volcano, which ...

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A very well evidenced essay, though at times lacking focus on the question. The case studies used were relevant and would benefit from further linkage back to the question posed. Some small tweaks would make this an excellent answer. 4 stars