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Describe the View That the Impact of Earthquakes Depend Primarily on Human Factores

Autor:   •  February 23, 2016  •  Essay  •  1,340 Words (6 Pages)  •  430 Views

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Describe the view that the impact of earthquakes depend primarily on human factores

  Earthquakes are caused by the movement of tectonic plates and fault lines covering the earths surface. They occur at all three plate boundries (distructive, constructive andconservative) although most earthquakes occuralong the edge of the oceanic plates and fault lines such as the San Andreas fault line situated in California USA. There is always a variation of factors that can influence how the seismic event will impact, both human and physical factors and both influence the outcome of the event.

 The main physical feature to impact the size and damage of the seismic event is the magnitude of the earthquake. However, this factor can be dealt with to a certain extent by the management and preparation for the event such as evacuation programmes and earthquake proof buildings. Other factors such as the location of the earthquakes epicentre. The depth of the earthquake impacts the strength of the seismic waves at the surface. A deeper focus means the waves will have less energy at the epicenter, so the risk of damage due to ground movement is reduced. The geographical landscape in which the earthquake occurs will also influence the impacts. If the epicenter is located in a rural area where it is a less densely populated area, the impacts are dramatically lessened. However, if the epicenter is located in close proximity to a city center during midday when there is a dense population or in a terrestrial area then the effects can be devastating. An example of this would be the Kocaeli earthquake on the 17th August 1999 in North West Turkey. Known as one of the biggest earthquakes in the 21st century, the magnitude 7.6 earthquake with 10 aftershocks, occurred at 3:01 in the morning when most were asleep and very vulnerable to the danger of an earthquake. Due to the sheer amount of people asleep in homes the death toll rose to 17,118, 50,000 injured and over 500,000 left homeless.

However, the same is not always true for earthquakes with a focus beneath the ocean. Although, due to the distance from the epicenter, the magnitude of waves on land may be smaller, there is a risk of the secondary impact of a tsunami. In Japan, in 2011, despite a magnitude 9 earthquake striking over 100 kilometers east of the Japanese coastline, the damage was relatively low. The majority of the costs of this seismic event were due to the resulting tsunami, caused by vertical displacement of land up to 10 meters.

 The rock type the earthquake occurs on can also play a huge part in the impacts the earthquake has. Buildings built on unstable rock such as Mexico City, which is built on unconsolidated lake sediment, will mean that the area is subject to more vulnerability should a large seismic event occur. In order to prevent these buildings built on less stable sediment more money is needed to be invested by the government to earthquake proof these buildings. There is also a risk of liquefaction occurring if sediment land is saturated with rainfall from past days. Liquefaction is where buildings sink as liquid rises to the surface when the surface is violently shaken. This can have secondary impacts as removal of excess water is costly and the structural damage is large.

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