A volcanic hazard refers to any potential dangerous volcanic process from primary hazards; such as lava flows, pyroclastic flows, ash falls or volcanic gases and also secondary hazards; including lahars and volcanic landslides. There are around 1500 potentially active volcanoes worldwide and therefore in my opinion, every volcanic eruption is unique and influences the hazards that are produced from it which will impact upon the environment, the economy and the population of an area. Although it can be argued that physical factors; like the magnitude, cause and give the greatest input into the initial impact, the human factors also have an influence on the effects a hazard can have, for instance the land use and demography.
The vulnerability of LEDC’s (Low economically developed countries) has a large effect upon the response and recovery to a volcanic eruption. The Nevada Del Ruiz volcano erupted in 1985 and left devastating impacts as a result of the demography; such as the densely populated areas surrounding. The pyroclastic flows and melting glaciers that created lahars killed 22,000 people and 150,000 animals due the speeds of the hazards travelling at 50km per hour; mostly suffocating those that died. However as well as this there were many long term impacts that had a huge influence due to the destruction of basic needs and services that the LEDC’s primarily relied heavily on; the whole destruction cost the government $7.7 million. Therefore international aid (the Columbian Red Cross and the Civilian Defence Personnel) and the military played an important role of the rescue activities; helicopter airlift which reduced the death toll and allowed civilians to get the medical care and basic requirements that were necessary. Sanitation is also a very important factor in maintaining a population’s health after an eruption. More specifically in the eruption that occurred in 2002 at Mount Nyiragongo, the spread of cholera occurred throughout the temporary refugee camps. The lava that flowed from the ground fissures of the crater lava lake reached speeds of 60km/h and reached the city of Goma which caused an evacuation of 400,000 people across the Rwandan border into neighboring Gisenyi during the eruption. Many evacuees spent nights sleeping on the streets with little shelter, electricity or clean water. Many people from LEDC’s are unaware of the health issues that could occur after and from a volcano eruption, a majority of the population lack a solid education and the government discovered that very few were aware of the potential hazards that could occur from any sized eruption. Therefore after the destruction of 50 schools from the Nevado Del Ruiz eruption a public education campaign was put under way in early 1986 to inform the population of volcanic hazards and what to do if an eruption occurred. LEDC’s are extremely vulnerable to the eruptions that occur especially with poorly built infrastructure, consequently the basic premise is that the volcanic outbreaks may not kill people but inadequate constructed buildings can. The eruption of Mount Sinabung from 2013-2014 destroyed countless houses, especially in North Sumatra when a 7km column of hot ash was spewed into the air and smothered the nearby villages which put weight upon the buildings causing them to collapse. Therefore many responses to volcanic eruptions have been known to support those that have lost their homes, businesses and services. Including the Mount Pinatubo eruption which caused the government to reconstruct new houses on stilts so the future lahars would not bury them; much like when 847 were killed by collapsing roofs in 1991.
Volcanic eruptions can differ in frequency, length and magnitude, furthermore on the 1st of May 2008 Mt. Chaiten in Southern Chile began violently erupting rhyolitic lava producing lava flows, minor earthquakes and lahars as well as a new lava dome and the lava was eventually pushed out the central spine of the dome in late May. Although the eruption continued for over a month the demography of the area had a huge influence on the potential impacts that could have occurred, for instance the remote populations that surrounded Mount Chaiten. Therefore although the eruption was violent there were no deaths of people or animals. Additionally the management and response to the eruption in 2008 was not high, despite the volcano having an explosive past. No real time monitoring was put into place until the USGS arrived on the 16th of May, around 15 days after the eruption, which caused a rushed evacuation of 4000 people from Chaiten and the town of Futaleufu costing the government $36 million.
The impacts that volcanic hazards cause are not just affecting a local region but it can similarly have an impact upon international countries. After the eruption of Eyjafjallajokull in Iceland LEDC’s like Kenya were badly affected. 20% of the Kenyan economy is based on the export of green vegetables and cut flowers to Europe. An ash plume rose 11,000m into the air (reaching the stratosphere), therefore these perishable goods could not be transported, which left over 1 million flower stalks unsold in just 2 days and over 50,000 farmers were temporarily unemployed.
The land use is another well known human factor that can hugely intensify the impacts of a volcanic eruption and its hazards. Mount Chaiten erupted in 2008 and the airport was destroyed, as well as 5 airplanes being unsafe to fly from the 17km high ash cloud that emerged which caused engine damage. As well as transportation issues the tourist lodges were also very likely to be impacted from the hazards. Such as the Mount Nyiragongo eruption in 2002 and as I mentioned earlier the lava reached the city of Goma meaning the tourist lodges that were overlooking the lake suffered an economic turndown for 3 years. Additionally a large amount of LEDC populations can be affected by the destruction of farmland due to heavily relying on the income of selling their crops and poultry as their main source of salary. Mt. Pinatubo that is found in North-East of the Philippines erupted in 1991 and had huge impacts when it destroyed 800km2 of farm land, costing just over 1.5 billion pesos in total. Although the mud from the lahars made the land more fertile, farmers experienced poor harvest which had further impacts on the population of nearby villages because they relied heavily on the produce from the farmers, consequently causing food shortages. Furthermore lava flows can cause large scale deforestation; another main source of income for locals, for example tens of thousands of prime forest was burned and destroyed when Mt. St Helens erupted. This had an effect on the logging industry, costing $4 billion. Forest fires were also a highly common secondary impact that occurred from pyroclastic flows. The Soufriere Hills eruption caused a massive decrease in timber and unemployment rose to 50%.
Although the income of volcanic hazards can depend on human factors, the physical factors are actually the reasoning behind the event itself. The eruption of Mount St. Helens famous eruption in 1980 is well known for the build up of activity and the creation of the largest landslide ever recorded exposing molten rock and gas, which exploded and avalanched down the North Face heading towards the Spirit Lake. Although the eruption caused huge impacts both short term and long term, it was however well monitored and early signs of an eruption were detected very early on. Scientists noticed that 2 months prior to the eruption small ash and steam eruptions were occurring and the bulge on the North side began to form, they also used tilt meters to monitor the changing size and shape of the mountain. The authorities were therefore able to evacuate any danger zones that they thought could be affected.
To conclude, although physical factors play a large role in the income of the size, frequency and length of volcanic hazards, I do feel that human factors can increase or decrease the impact of an eruption that we may receive. Although like I said earlier every volcanic eruption is unique, however my point is, if the income of a volcanic hazards is extraordinary, could it have a smaller impact because of the vulnerability and demography of an area is low? Or if the land in proximity to the volcano is not being used for anything significant, will it have an impact? What if the volcano is heavily monitored and the government is prepared for an eruption?