Discuss the nature and impacts of one or more volcanic events that you have studied.

In 1991, Mount Pinatubo in the Philippines erupted with huge explosivity, due to a large build up of gas in the magma chamber in the lead up to the eruption. A main primary hazard was the ejection of a huge ash cloud, which then mixed with rainwater to form a mud like substance which damaged many buildings in the local area. However, the most notable impact of the ash was its long term impact on the global climate. The smallest ash particles remained suspended in the stratosphere in the years following the eruption, which lowered global temperature by as much as 2 degrees Celsius. The eruption was the direct cause of up to 900 fatalities.The eruption of Nevada Del Ruiz in 1985 displayed some similar hazards to the eruption of Pinatubo, yet the impacts were very different. Meltwater from the glacier capping the volcano mixed with volcanic debris and lava (which was less viscous than in Pinatubo on account of the lower gas content), forming destructive fast moving lahars reaching up to 30m high. This was the primary cause of the death of 70% of the population of the local town; up to 25000 individuals. The reason why this eruption had a significantly larger social impact than in Pinatubo was due to the lack of prediction and preparation measures in place. For example, prior to the Pinatubo eruption, the Philippine Institute of Volcanology and Seismology successfully forecasted a volcanic event and evacuated the local areas. Such monitoring services were not available in Nevada Del Ruiz at the time, therefore the eruptions' most severe impacts were social and immediate, whereas the Pinatubo eruption had most effect environmentally, and on a much larger spatial and temporal scale.