To discuss this view there is a need to understand what a hazard is and what are the volcanic hazards. A hazard is something that causes danger or risk. In the case of volcanic activity it is an event which can cause risks to human life or the surrounding environment. There are specific hazards which occur with volcanic eruptions such as pyroclastic flows, lava flows and the gas emissions from the volcano however there are also secondary hazards that can occur such as lahars, landslides and tsunamis. These are all natural however, the impacts can be worsened by human activity. The impact on humans depends on the amount of human activity surrounding the volcano and the human activity which occurs within the greatest risk area. Around the world, volcanic events can vary in both size and frequency this can be down to the type of plate boundary that the volcanoes lie on but also the type of lava that is known to that volcano.

It can be argued that the volcanic hazards depend on the physical factors rather than human factors. For example the eruption that occurred in Iceland in 2010. There were 2 phases which had distinct physical differences and this then affected human activity in a number of different ways. Eyjafjallajökull’s first eruption occurred on the 20th March 2010 and it lasted 6 weeks. It didn't gain much interest from world wide media due to the fact there wasn't any explosive events which affected other parts of the world. This was down to the fact the lava that came from the eruption had a low viscosity meaning the lava is thin and it travels large distances. This wasn't a destructive eruption and there was little ash produced. On the other hand on the 14th April in the same year there was another eruption. This time it caused global disruption. The lava was of a high viscosity but also due to the ice on the peak of the volcano there was 250,000m3 of ash produced which was released into the jet stream 27,000ft high. It then travelled 3000 miles. Due to the differences in physical aspects of the eruption, it caused different effects on human acitivity. For example due to the april eruption flights were cancelled so those on holidays couldn't get back from their destinations causing them to miss work which had a large economic impact on Northern Europe. This eruption also affected Kenya, due to the fact Kenya export a large amount of flowers to Europe via aeroplanes, these planes couldn't fly so the flowers couldn’t be exported and due to the fact the flowers were perishable and had a short shelf life Kenya suffered vast economic impacts from this eruption. This second eruption cost UK airlines £10 million per day and many businesses went out of business. This is arguably due to the physical differences of the volcano.

However, surely the amount of human activity in a risk zone will increase the impacts that a volcanic eruption has. If there wasn't any life near an eruption then wouldn't there be less of an impact?

The land use and infrastructure of the land surrounding the volcano can increase or decrease the impact that the volcanic eruption has on the surrounding area. For example if there are many buildings and houses in the risk zone of the volcano there will be a larger impact. Whereas if there were less buildings in the risk area this would decrease the destruction and impacts of the eruption. If an area is more densely populated there is widespread destruction, for example in the Philippines when Mount Pinatubo erupted in 1991. Pinatubo is located on the Island of Luzon and close to the tripoint of Zambales, Tarlac and Pampanga. These are densely populated which is why there was such widespread impacts, for example 364 communities and 2.1 million people were affected by the eruption along with 8,000 houses destroyed and over 73,000 damaged. These were due to the pyroclastic flows and a lahar which was triggered from the eruption. A lahar being melt water from ice or a glacier located on the volcano. The GDP of The Philippines was decreased by 3% due to this eruption. However, there have been eruptions with a similar hazards such as the eruption of Mount St Helens in 1980. There was approximately 540 million tonnes of ash deposited over 57,000km2. But from this catastrophic eruption there was an unusually small amount of social impacts to what one may have expected. For example when Mount St Helens erupted there was an unusually small amount of deaths of 57 people, even though this was tragic compared to Pinatubo’s 847 deaths it was significantly smaller. However, there was 240km2 of forest destroyed. This was due to the eruption occurring on the north face of the mountain, where there was less inhabitants.

Another human factor that can affect the level of impact that a volcanic eruption has on the surrounding environment is the level of education that the inhabitants have. The more education there is, in the country where the volcano is located tends to decrease the impact that the volcanic eruption has on the area. The level of education not only influences the amount of monitoring that the volcano receives but also the beliefs about the volcano. A classical example of alternate beliefs is the people living on the slopes of Mount Merapi. Mount Merapi is located in Indonesia on a destructive plate margin where the Indo-austraian plate is being subducted under the Euro-asian plate. The javanese people believe that in order to stop eruptions there is a need to appease the spirits of the mountain therefore they bring the volcano offerings as they believe that it is a God. There is a spiritual guardian who is believed to have the power to speak to the spirits of the mountain by the local people. This is why when there was seismic activity in October 2010, no-one evacuated even though there were 75,000 people living within 20km of the volcano and they were told they needed to evacuate. Even when the eruption was occurring many refused to be evacuated which then caused 275 deaths to occur. Whereas, in Sicily people also live on the slopes of Mount Etna. They live here due to the fact that the land is highly fertile from the materials released by the volcano. There has only been 77 recorded deaths due to eruptions from Mount Etna and these are usually visitors not residents. The difference between these two case studies is that Sicilians base their knowledge of the volcano on scientific evidence rather than the javanese who base their beliefs on historic cultural beliefs.

Furthermore, the ability to deal with an eruption before, during and after the event is important when looking at the impacts on humans and the environment. Volcanic eruptions are a natural occurrence and they cannot possibly be prevented. However, the impacts that occur after the eruption, can be planned and therefore managed to a higher standard meaning that they are less catastrophic and those people that will be affected will be prepared or evacuated before the eruption occurs. Usually, if a country is an MEDC such as Iceland they tend to have more scientific studies completed and ongoing on the volcano. For example Eyjafjallajojull is constantly monitored. This allows the Government to be able to warn those of Iceland when there is a likelihood there will be an eruption. Whereas in Colombia where Nevada del Ruiz is located, there isn’t enough money or education in this country - due to the fact it is an LEDC - to monitor this volcano constantly. This means there is less of a chance of an evacuation of the people surrounding the volcano, which means there is more likely to be an increased amount of deaths due to an eruption. Also, the ability to communicate evacuations and put in place plans incase of emergency is important. An example of an eruption which was prepared for is in Iceland and the eruption of Eldfell, where by they evacuated every inhabitants on the island within 2 hours of the eruption beginning. This lead to the safety of those on the island and when the eruption had finished they then had the money and ability to deal with the aftermath of the eruption and the devastation it had caused. Whereas places such as Columbia do not have the money or ability to do this. For example when Nevada del Ruiz erupted it left 23,000 dead due to the initial eruption, lahars racing into towns such as Armero and deaths due to diseases such as cholera. Those who survived those were also at risk of yellow fever. There were evacuations put in place but the people didn’t receive the warnings due to the fact they didn't have TV’s or radios. Also, those that received the warnings couldn't understand them. Furthermore, the Colombian government had accused the scientists that warned them of scaremongering (creating stories to scare the people of Colombia). There was then need for aid to be sent in from other countries and aid workers to help rebuild the towns that had been destroyed. However, this was difficult as there was little money available in the country and it was hard to transport supplies and people due to fallen down bridges and broken roads. In my opinion, this is a massive influence on the amount of devastation caused by volcanic eruptions due to the preparation and the ability to deal with those eruptions. How can a country bounce back from a natural disaster if there is little money and expertise?

Lastly, the timing of the eruption plays a vital role as to the impact it has on the people. This is a physical factor due to the fact that the time of an eruption whether it be time of day, which day of the week, whether it is summer or winter or how long it has been since the last eruption cannot be changed or manipulated by humans. However, it can impact humans differently depending on the time of the eruption. For example if it occurs during the day it can have a smaller amount of deaths due to the fact that people are able to escape the eruption whereas if it happens at night it can have a highly death toll as many will die in their sleep. This is what happened when 1.6 million tonnes of CO2 was released from Lake Nyos in Cameroon. Also, the time of week can have an impact due to the fact that if an eruption occurs on a Sunday more people will be at home therefore the death toll could be higher rather if they were at work if the eruption occurred during the week. Furthermore, the time of year that a volcano erupts can have very different effects. If it is during winter and people are made homeless this can increase the number of deaths due to the fact that if people are homeless the conditions will be harsh and this can cause people to freeze to death. Moreover, the time since the last eruption can affect impact. If there have been recent eruptions there will be plans in place such as in Washington State regarding Mount St Helens. Whereas if the volcano is still deemed to be active but hasn't erupted in the lifetime of the current local residents this may cause their government to either not have a plan or not to take the volcano seriously. For example Mount Tongatiro on the North island of New Zealand. This erupted in 2012 and although no-one was killed as it was a calm eruption, many of the local people stood and watched the eruption. To me this shows the difference between those used to eruptions and those not used to eruptions. Those people in New Zealand may have been too naive about this eruption and they were lucky it was a calm eruption otherwise impacts may have been a lot worse.

Overall, the impact of volcanic hazards do depend on both the physical and human factors. It could be stated that if the actual event is larger this will have greater impacts overall, however the impacts are heightened considerably when there are human factors that come into play. The impacts seem to be smaller when there is no obvious effect on human life. There is no possible way of preventing these natural events therefore the emphasis needs to be on how to minimise the risks and hazards of a volcanic eruption.