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To what extent can preparedness and planning mitigate the effects of volcanic hazards

By SoggyHobNobs May 04, 2015 1382 Words
To what extent can preparedness and planning mitigate the effects of volcanic hazards? (40 marks)

A volcanic hazard is anything that can cause a threat to human life, infrastructure or nature as a result of volcanic activity. There are methods to lessen the effects of volcanic hazards to a certain extent through planning and preparation. Common volcanic hazards include: Pyroclastic flows, Ash clouds and mudslides. Pyroclastic flows are high-density mixtures of hot, dry rock fragments and hot gases that move away from the vent of the volcano at high speeds. They can reaches speeds moving away from a volcano of up to 450 mph and the gas can reach temperatures of about 1,000 °C. They will catch fleeing victims and kill them instantly thus making them a devastating hazard. Volcanic ash is formed during explosive volcanic eruptions when dissolved gases in magma expand and escape violently into the atmosphere. They can also have devastating effects due to the similar heat as pyroclastic flows. They have secondary effects as well, such as stopping air travel simply because it is unsafe. Navigation is difficult and the cloud is still dangerous. The fine ash erupted from explosive volcanoes can cause destructive mudflows. When a volcano erupts, ice and snow melted by the heat of the eruption run downhill carrying ash particles and other debris. They can flow tens of metres per second, be 140 metres deep, and destroy any structures in their path. Preparation is linked to prediction. There are many ways to predict volcanic activity which allow us to plan the next steps on how to mitigate the effects. We cannot fully predict events however we can use different methods to help us be as prepared as possible. Often the first sign of volcanic activity is waves or tremors coming from the volcano; these can be measured using a seismometer. This will then show up on a seismograph and this data can be used to monitor volcanic activity. Once volcanologists determine that the volcano is active they will then carry out a number of different monitoring methods which allow them to understand what the volcano is doing in more depth. When water is heated by magma volcanic gasses can be produced, most commonly sulphur. Sulphur will alert them that an eruption is likely. This gas will escape upwards out of the volcano meaning it can be monitored by volcanologists using a correlation spectrum or COSPEC. From this they will be able to determine the content of the gas; from this they will be able to tell how likely the volcano is to erupt. Thermal imaging and GPS signals can also be used to monitor the volcano. Thermal imaging will be used to see how close to the surface plumes are and the size of them. If the lava is rising upwards then it is clear that an eruption is very likely. GPS signals are used to watch the shape of the volcano, volcanos quite often expand outwards when there is a build-up of gas and lava known as a bulge or plume. This will help the volcanologists not only predict when the volcano is going to erupt but also what type of eruption it might be and plan the possible direction of lava flows. Similarly, a tilt meter can be used to measure the surface of the volcano and see how the shape of the ground changes, this data can be used in the same way; to predict eruption type and magnitude. Knowledge of volcanos can also be used to help predict eruptions. The type of volcano is determined by the plate boundary on which it sits. On a divergent plate boundary, these would be fissure volcanos. These volcanos tend to be shield shaped and erupt effusively meaning the basaltic lava doesn’t explode out, instead it pours out of the smaller vent. An example of an effusive volcano is Giant’s Causeway in Northern Ireland. The shape of a volcano also gives clues as to how it might erupt, shield volcanos erupt effusively but the lava travels a long way. At the other end of the spectrum is explosive volcanos found on convergent plate boundaries, known as plinian volcanos. These gives off rhyolitic lava in an explosive manner. Mount st Helens in Washington is an example of this. Caldera volcanos erupt explosively; the lava travels up but doesn’t go very far. Knowledge of the volcano in question can help volcanologists plan and prepare as volcanos erupt similarly each time. Having knowledge of prior eruptions is a huge advantage for volcanologists as it gives them a very strong idea into how the volcano will erupt. The knowledge will involve all hazard details such as what hazards will occur, where they will go and what other effects could happen. This will force them to have to look at the location of the volcano and asses the risks it poses. For example if it is in an urban area with many people in close proximity such as Mount Etna where people actually live on the slopes of the volcano, it poses greater threats than if it was in a secluded area. All of this knowledge is perfectly good for volcanologists to have, however they must communicate with governmental organisations such as the Institute of volcanology (INGV) in Sicily. Once the information has been communicated across then a plan must come into action. Hazard mapping is the first step; this allows them to plan and predict where the hazards are most likely going to occur. This is important information and it is needed to help decide what to do next. An early warning will be issued to all emergency services and state governments that may be affected; the early warning helps further preparations. The next step which will be taken at all volcanos is an evacuation plan. This is basically instructions on what to do for everyone in areas deemed unsafe should they need to evacuate. This is important as getting people out safely and quickly will save lives. An optional step is to try and divert the lava using structures. This will take time so early warning and preparation is very important and it can be expensive and therefore only really an option for MEDC’s. However when done well can save lives, buildings and habitats. They would be placed using the knowledge of previous eruptions and looking at where the pyroclastic flows went before. Montserrat is an exception because it was such a hot spot for volcanos that the MVO was established by The UK and the USA to give funding and training for volcanologist that could study Montserrat. They will have to think about protecting human life, the environment, infrastructure, social factors and economic factors. Human life is always top priority; however they will have in mind the ratio between cost and benefit to decide whether certain techniques are worth it. The eruption in Iceland in 2010 caused huge economic loss as so many flights had to be cancelled due to the ash cloud, however this could not be managed. Social factors then arose as people were left stranded and couldn’t travel either home or away for business or pleasure. The eruption of Mount Pinatubo cause huge environmental issues as the temperature rose dramatically which lead to more severe weather. In general, lesser developed countries will have more devastating effects as they don’t have the money or resources to build defences or monitor the volcano in the first place; this however is not the case in Montserrat. Because it is known for frequent eruptions, the UK and USA use it as good practice to monitor and protect and therefore the area has benefitted and despite being an LEDC has good programmes in place against the volcano. Volcanos are unpredictable and despite all the preparation and planning, they could erupt at any time. This means that there is always going to be negative affects no matter how much preparation and planning occurs. Therefore, yes, effects can be lowered through good preparation and planning however there is always going to be hazards that lead to negative effects. These effects can be mitigated to a significant extent, but never fully eradicated as actors such as temperature change and ash cloud are extremely difficult if not impossible to stop.

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