It is the viscosity of magma that largely determines the nature and power of an eruption and the resultant severity of the hazard. Basic magma has a high proportion of dissolved gases and low silica content, making it very fluid. On the other hand, acidic magma is very rich in silica and has a relatively lower temperature, making it very thick and slow moving. The more viscous the magma, the greater the potential for explosive eruptions and these represent the greatest potential hazards. Non-explosive eruptions tend to produce mostly lava flows, which do not represent a particularly serious hazard to people, however they will destroy farmland and buildings.
Viscosity can be affected by three main factors, Firstly, the higher the temperature, the lower the density of the magma, causing it to flow more easily. Secondly, the greater the amount of dissolved gases in the magma, the less viscous it will be, and lastly the higher the silica content, the more viscous it will be. Thicker, more viscous magma has a greater potential for explosive eruptions and therefore represent the greatest potential hazards. The thickest type of magma is known as Acidic Magma. Its relatively low temperature, high silica content and leads to blockages and powerful eruptions.
Analyse the factors that cause differences in the hazards posed by volcanoes around the world (40 marks) Volcanic hazards pose a risk to people and their property in both primary and secondary form. A volcano is an opening in the Earth's crust which lava, ash and gases erupt. A volcanic eruption can cause many deaths, illnesses, destruction of infrastructure, crops and livestock, all which will affect the economy and GNP of a country. There are many factors involved which cause differences in the severity of the destruction caused by a volcano, such as, locations of settlements, monitoring, plate boundaries and the economic status of a country, however these are different for each volcano around the world. I will be discussing factors that cause differences in hazards posed by volcanoes.
To what extent to you agree with the view that the hazards resulting from earthquakes and volcanic activity cannot be managed but merely adapted to. Earthquakes and volcanic activity are both nature disasters that human can’t control when or where it will happen and it may cause lots of death and economic loss. There is no way that we can stop it from being happened but we can definitely try to adapt it by many different ways. Firstly, volcanoes are found at destructive and constructive plate margins. At destructive plate margins, the oceanic plate goes under the continental plate due to it’s more dense, which is a process known as subduction.
The scale or better known as magnitude of the earthquake effects these characteristics and determines the physical destruction. The local geology of the area such as whether building on reclaimed land can have huge toll on building destruction and impact on hazards. Along with this the proximity of the earthquake to the coast can have a huge impact on the hazards. If the earthquake occurs out at see the tsunamis can be just as devastating if not more destructive than the earthquake. It would result in services being unable to reach areas due to the flooding and many more lives could potentially be lost.
The most devastating effect of drought in California is wildfires – dry vegetation is extremely flammable, so fires spread quickly over wide areas. 5. The wildfires in Southern California in October 2007 killed 22 people and destroyed 1300 homes. Tsunamis 1. A tsunami is a series of large waves that can flood coastal areas.
Benzene has been known to be a carcinogen, while the rest of the chemicals are unknown what long term damage it could cause. Another danger of fracking are spills. Spills occur during the adding of the fluids as well as during the results of the flow back. Drill operators will eventually have spills throughout this process. Hoses can be undone, gaskets can fail, pits leak and liquids always hit the ground, repeatedly in large quantities.
I shall use examples of the Kobe Earthquake 1995, Boxing Day Tsunami 2004 and the Haiti Earthquake 2010. The earthquake of 2004 was caused by subduction of the Australian plate and the Eurasian Plate ,a 15-20m slip occurred along the fault line which then caused an earthquake measuring a 9.1 on the Richter scale. This a very high recording on the Richter scale so therefore it would always cause devastating hazards , but human factors could be seen as making the impacts far worse. The earthquake in the ocean had caused a tsunami to occur within the Indian Ocean. The wave reached up to 30 metres high causing devastation to the 13 countries surrounding the ocean.
The pyroclastic flow from Mt. St Hellens destroyed everything within 25Km of the blast zone, this included all life and trees. Thousands of animals and birds were killed in an instant. * Amazingly only 57 people were killed in this natural disaster, mainly by the poisonous gases from the pyroclastic flow, but also from flooding. (Pyroclastic Flow on Mt St
They grow by piling up lava and ash into cones with steep-sided slopes, which are prone to collapse as massive landslides known as debris avalanches. The 1980 debris avalanche at Mount St. Helens literally opened a new chapter in the study of volcanic hazards. Debris avalanches were an under-appreciated hazard prior to 1980. More than 200 prehistoric debris avalanche deposits around the world were recognized because of observations of processes and resulting geologic features at Mount St. Helens. For example, the origin of puzzling, hilly volcanic deposits near Mount Shasta and Mount Rainier became clear.