Composite Volcano Eruption Case Study
Volcanoes are some of the most devastating natural hazards and when they erupt they can evoke awe and wonder in us all. Volcanoes are basically mountains that can explode with violent consequences. Volcanoes are a geological landform created by the intrusion of magma into the earth's crust and by the eruption of that magma onto the Earth's surface through a vent. There are many different types of volcano, and they are classified in different ways according to their type of eruption, the material ejected and their activity. You can see theBBC's animated guide to volcanoes here.
According to the activity of volcanoes, there areextinct, active, and dormant categories. Easily recognized volcanoes are active volcanoes, but dormant and extinct volcanoes are difficult and dangerous sometimes. The people living near known extinct and dormant volcanoes must always be on the lookout. Volcanoes can erupt at any time without warnings.
The constantly erupting volcanoes are active. The eruption is usually quiet but can sometimes be violent. Stromboli, which lies on an island near Italy, is a famous active volcano.
Intermittent volcanoes erupt at fairly regular time periods. Mount Asama, Mount Etna, and Hualalai are some intermittent volcanoes.
Inactive volcanoes that have not erupted for an amount of time but can’t be called extinct are dormant volcanoes. They can be called “sleeping” volcanoes. (seeThinkquest for more)
Inactive volcanoes which have not erupted since the beginning of recorded history are extinct volcanoes. They will never erupt again unless they are still dormant and have been mistaken for extinct volcanoes.
Types of volcano
Eyjafjallajökull is a small volcano (about 40km2) within the chain of volcanoes in the SE Rift Zone. It is the most southerly volcano on mainland Iceland before Surtsey in the sea to the south west. It is a relatively small volcano, and is located W of Katla volcano. Eyjafjallajökull consists of an elongated ice-covered strato volcano with a 2.5-km-wide summit caldera. Fissure-fed lava flows occur on both the E and W flanks of the volcano, but are more prominent on the W side. Although the 1,666-m-high volcano has erupted during historical time, it has been less active than other volcanoes of Iceland's eastern volcanic zone, and relatively few Holocene lava flows are known. The last historical eruption of Eyjafjallajökull prior to an eruption in 2010 produced intermediate-to-silicic tephra from the central caldera during December 1821 to January 1823 (Source).
The nature of the volcanic hazard – type, frequency, magnitude
The major problem with this volcano was volcanic ash and the ash plume that resulted from the eruption. This ash plume reached 11,000m into the air, high enough to reach into the Stratosphere and also to be distributed by high velocity jet streams between the Troposphere and the Stratosphere. The problem with the ash was that it was very fine grained, a sample taken by the Environment Agency on Mýrdalssandur (50 km away from the eruption site) after the ash fall 14-16 April was analysed by Institute of Earth Sciences and is very fine grained:
24% of the sample is under 10 μm (as aerosol)
33% of the sample is in the range of 10-50 μm
20% of the sample is in the range of 50-146 μm
23% of the sample is in the range of 146-294 μm
This fine grained ash poses a problem to airplanes, as it can affect many systems when it enters the engines and even turn to a glassy substance because of the heat of the jet engine.
Britain had fine anticyclonic weather for a lot of the time that the Ash cloud existed. This was a problem because winds would have dispersed the cloud better.
The other complicating factor is that the volcano is covered by the Eyjafjallajokull glacier. This caused a flood (a jökulhlaups - glacier outburst flood) on the 14th of April, when an eruption partly melted a glacier and set off a major flood which prompted authorities to order 700 people to evacuate. This flood had huge discharges of 2000-3000 m3/sec
The volcano also emitted lava from a 500m long fissure, spewing the 1,000°C lava 150m into the air. The volcano was classified with a VEI of 4, with greater than 1.4 ± 0.1 x 107 m3 (100 million cubic meters) of lava erupted and > 1.4 x 108 m3 (1,000million cubic meters!) of Tephra erupted (source). It was also categorised as both a fissure and explosive eruption.
Before the eruption in 2010 the volcano is known to have erupted in 920, 1612, 1821 and 1823. Between March the 3rd and 5th of 2010 there were plenty of warning signs of an eruption, as there were over 3,000 recorded earthquakes, the vast majority of these being less than 2 on the Richter scale and only some large enough to be felt in nearby towns.
The vent for the volcano is 1.8 to 2.5 miles across, and is located close to a much more active volcano, Katla. Scientists were very concerned at the time of the eruption that this eruption could be a precursor or warning sign of a much larger eruption of the historically more active and dangerous Katla. This volcano erupts more often and is known to be more violent. This area is therefore incredibly vulnerable to this sort of activity, but weather conditions made the effects of the ash must worse.
Capacity to cope and institutional capacity (prediction, preparation, prevention)
The Icelandic Meteorological Office monitors earth movements, water conditions and weather and issues warnings. Many kinds of measurements are carried out by the IMO and other agencies that provide valuable information used to warn of impending danger, for example potential eruptions and floods. The IMO's weather radar on the southwest tip of the country showed the height of the ash plume, which is important for calculating the distribution of the ash. There was a 24/7 watch at the IMO, where a meteorologist is present and a seismologist and hydrologist are on call. The IMO worked closely with the National Emergency Agency, the University of Iceland and the British Meteorological Office, where the London VAAC (Volcanic Ash Advisory Centre) is stationed. The London office gave information on ash which is based on information from the Icelandic Met Office. This event was therefore tracked and prepared for, and the ash cloud was tracked by satellite by many nations. In addition, all of the countries in Europe have bodies which determine the safety of conditions to fly in. This means that many of the countries have great capacity to cope in terms of making predictions and preparing alternatives for companies and people stuck by the restrictions on air travel.
The European Union is a trading block which has a very large combined GDP of $24400; this means it has the collective financial capacity to cope with emergencies like this eruption. In addition, the EU has other transport mechanisms such as extensive road and motorway networks, rail networks (including the Channel tunnel) and boat networks (which were particularly important for the transportation of food goods etc.). In addition, the EU’s CAP means that the EU is largely self-sufficient in food production and could cope if imports from outside of the EU could not arrive. Finally, in legal and insurance terms the EU is well prepared. Travelers stuck by the ash cloud were entitled to legal compensation from their airlines and their airlines were also legally responsible for the well-being of stranded passengers. Also, the EU’s insurance system means that many people (but not all) would have been able to claim back any losses, as could many companies. Finally, many companies had contingency plans in place for an emergency such as this, so could cope better, Tesco circumvented the ash cloud by flying Kenyan produce into Spain and then using road haulage for example.
The impact of the event (social, economic, environmental), in the short and longer term
Within Iceland many people were very lucky as the volcano is on the south coast and the wind carried the ash southeast towards Europe: away from the most inhabited areas of Iceland. However, the people living in the rural areas ‘down wind’ of the volcano had to wear goggles and facemasks as the ash was so thick. Indeed, visibility was down to a few metres and local cattle farmers suffered. 500 farmers and their families had to be evacuated from the area around the volcano, and many of the roads surrounding the volcano where shut down. The ash contaminated local water supplies and farmers near the volcano were warned not to let their livestock drink from contaminated streams and water sources, as high concentrations of fluoride from the ash mixed with river water can have deadly effects, particularly in sheep.
The major impact was Internationally however, as winds redistributed the ash that was pumped high into the atmosphere over Northern and western Europe and stopped flights from taking off. The map shows the extent of the ash cloud, note it interrupts not just European flights but also Trans Atlantic fights. Although the ash cloud was invisible to the naked eye, as it is made up of very fine particles and substances. These particles clog up the engines of aircraft that attempt to fly through them, and this is the reason for aviation disruption.
Animation of ash cloud spreading
This also has a knock on effect on International flights globally as they could not land or take off from Europe. This is thought to have cost Airlines and associated businesses were losing about £130 million a day (according to the IATA), whilst hundreds of thousands of people (including me!) were stranded in other countries. Hire car companies and other forms of transport Hiked their prices as people sought other ways to get home, on my way back from France I met people who had paid thousands of pounds to hire a car to get them to Northern France to take a ferry.
This also has a huge impact on public institutions (such as schools) and businesses, particularly those who rely on air freight or those whose workers were stranded overseas. During the main 8 day travel ban around 107,000 flights were cancelled accounting for 48% of total air traffic and roughly 10 million passengers.
LEDCs were also badly affected, with Kenya being a great example. 20% of the Kenyan economy is based on the export of green vegetables (beans, sugar-snap peas and okra) and cut flowers to Europe. These are perishable goods and they are transported by plane to keep them fresh but the flight ban meant that products returned unsold and destroyed. Over 1 million flower stalks were unsold in the first two days and over 50,000 farmers were temporarily unemployed as their beans and peas could not be sold.
There were many environmental impacts of this eruption, and scientists feared a climatic impact. However, despite the Eyjafjallajökull eruption putting up to a maximum 30000 tonnes per dayof CO2 in to the air, it is thought this will not make a substantial addition to global anthropogenic atmospheric CO2 emissions (source).The main risks were to soils and water courses. The main risks are to livestock through fluoride ingestion from volcanic ash on pasture.
Responses to the event.
Many of the responses have been covered above, but it is important to recognize that unlike in LEDCs and LDCs the responses were entirely DOMESTIC. That means that the countries affected by this hazard responded by themselves or collectively, and had the capacity to do so. Their legal, technical and infrastructure systems can cope with hazards such as this eruption, even if there are economic impacts. Their actions also limited the impact in terms of casualties, and tests have taken place since to see if planes can fly in ash clouds, in what type of ash or around ash clouds.