Volcanic activity happens across the surface of the globe and naturally hazards occur too. A hazard is a situation that poses a level of threat to life, health, property, or environment. It is easy to locate volcanoes, but it is very difficult to predict exactly when activity will take place, particularly a major eruption, this makes it difficult to prepare or plan for one. There is a very big difference that helps prepare for a volcanic hazard and that is whether you are in a MEDC or a LEDC. In a MEDC monitoring volcanic zones and potential hazards is an option many LEDC’s don’t have. In Italy at Mt Etna they have Geo-monitoring programs which focus on the analysis of any changes. This option open to the Italians is not an option for LEDC who don’t have the wealth or public education to set up these stations. The Colombian volcano, Nevado del Ruiz, came to life in late 1984 with small-scale activity. Volcanologists from the US knew the danger a major eruption could pose to the surrounding area, but were unable to predict when the major event would take place because of a lack of resources.
Small-scale volcanic activity continued for several months and people were not prepared to evacuate their homes on the basis of this threat. MEDC can greatly reduce the hazards of a volcano in lots of ways. These include creating an exclusion zone around the volcano, being ready and able to evacuate residents and having an emergency supply of basic provisions, such as food. A study of the previous eruption history of a volcano is important in prediction, along with an understanding of the type of activity produced. At present, research is being conducted to see if it is possible to predict the time of an eruption accurately using the shock waves that are produced as magma approaches the surface, expanding cracks and breaking through other areas of rock. There was some success in predicting the recent eruption of Popocatépetl in Mexico, but it remains to be seen if such techniques can be applied to all volcanoes. With volcanic activity, protection means preparing for the event. Monitoring of the volcano may suggest a time when the area under threat should be evacuated.
Such monitoring includes observations of land swelling, earthquake activity, changes in groundwater level and chemical composition, emission of gases, magnetic field studies and the shock wave analysis mentioned above. Several governments of countries in volcanic areas have made risk assessments and from them produced a series of alert levels to warn the public. Geological studies of the nature and extent of deposits from former eruptions and associated ash falls, lahars and floods may also provide evidence for hazard assessment. Following assessments, it is possible to identify the areas at greatest risk, and land use planning can be applied to avoid building in such places. Once the lava has started to flow, it is possible, in certain circumstances, to divert it from the built environment by digging trenches, using explosive activity, by building artificial barriers, which also protect against lahars, or by pouring water on the lava front.
Foreign aid to developing countries suffering volcanic eruptions may be required for considerable periods of time as volcanic events can be prolonged and devastating to the local economy. Such aid is needed for monitoring, evacuation, emergency shelters and food, long-term re-settlement of the population and restoration of the economic base and the area’s infrastructure. Human factors that affect volcanoes include population density, poverty, and volcano mitigation because this affects the process of evacuation, knowledge and understanding. Human factors also include the effectiveness of government with disaster planning.
Physical factors that affect volcanoes include tephra, pyroclastic flows, lava flows, volcanic gases and lahars. In LEDCs you can have traditional tribes living in the path of the volcano, to educate them as to what happens when a volcano explodes you can show them videos and educate them so that when they need to be evacuated from their village, they leave. This was done in the 1991 eruption of Mt Pinatubo. In conclusion, it is difficult to predict when a volcano is going to erupt with any degree of accuracy and timescale which means that it is also difficult to prepare for it. However, it is usually easy, if the volcano is being monitored, to say whether it will or won’t erupt, this means that a plan can be put in place if the situation escalates.