To What Extent Can Preparedness and Planning Mitigate the Effects of Volcanic Hazards?
To what extent can preparedness and planning mitigate the effects of volcanic hazards? (40marks)A volcanic hazard is a threat to human life or property due to volcanic activity caused by tectonic activity. The main hazards caused by volcanic activity include pyroclastic flows, lahars, lava flows, ash clouds and release of dangerous gases. These hazards have many impacts on people and their environment. However, some of these impacts can be reduced by management strategies such as prediction and planning in order to be prepared for an imminent eruption. The impacts of volcanic hazards may be dependant on the type of eruption that occurs- whether it is violent with fast flowing lava or a prolonged eruption releasing large quantities of gas and ash, for example. The primary factors that determine whether a volcano erupts violently or quietly include magma composition, magma temperature, and the amount of dissolved gases in the magma. In addition, the severity of the impacts of volcanic activity are also affected by the development level of a country, the population of area involved and the timing of eruption. Many countries are able to prepare for a volcano as they constantly monitor changes in the volcano that may signal a fast approaching eruption. Scientists are able to measure the composition of gases emitted, study ground deformation using surveying equipment; measure seismicity and hydrology; and use remote sensing all to determine when a volcanic eruption may occur.
Mt. Etna is Europe’s highest (3,310 m) and most active volcano. It is situated in Sicily and has a large history of eruptions stretching over 5,000 years. Etna’s volcanism stems from the subduction of the African plate beneath the Eurasian plate. Mt. Etna is a composite stratovolcano that typically erupts balsaltic lava, which has a low viscosity and is consequently able to travel long distances. It could be argued that towns and villages surrounding Mt. Etna should be relatively well prepared as volcanic eruptions are fairly frequent and is a known hazard. However, although it can be destructive, the volcano is not regarded as particularly dangerous with thousands of people living on its slopes and in the nearby areas. Towards the end of 1991, lava began to pour from vents high on the eastern flank of the volcano in the Valle del Bove, and to advance to the settlement of Zafferana. This was very slow moving lava- taking around an hour to travel 100 m but was initially destroying everything in its path. A series of protective measures were put in place to halt the lava flow or at least slow its speed. A large earth barrier was constructed 30 m high and more than 400 m long. It held the lava back for several months. When the lava started to spill over it was decided to off the flow by blocking the primary feeder channel. Initially attempted by dropping concrete blocks from helicopters through the roof of the upper lava tube. Finally, engineers blasted opening in the lava tube to encourage a new direction of flow, rather than feeding it. The lava front stopped advancing towards Zafferana and the eruption ended 10 months later in early 1993. Zafferana and nearby areas suffered minimal damage with few homes directly affected from the lava and no deaths. The lava flow did manage to destroy farmland in Valle del Bove and plants such as orchards. The largest social impact was the destroyed water supply that cut off running water to 8,000 people. However, there were no major consequences following that up. The negative effects from this volcanic eruption very little due to the efficient response in stopping the lava flow. Engineers would have been ready to respond as the volcanic activity was closely monitored, along with this they had a fair amount of time to draw up an action plan due to the slow pace of the lava. With Sicily being a part of Italy, which is a wealthy developed country, the government was able to afford the management strategies, which stopped the lava. Even with all the planning and preparedness of the response team, the outcome could have been a lot more devastating subject to little/ no funding.