Volcanic Explositivity Index/ Type Of Eruption
The volcanic eruption of Mount Pinatubo caused a death toll of 853. It had a VEI of 6 and was a plinian eruption. The Soufrière Hills Volcano had a VEI of 3 and was a sub-plinian eruption. 19 people were killed.
Mount Pinatubo is located on a destructive plate boundary, where the Phillipines plate subducts beneath the Eurasion plate. The Phillipine plate turns into molten magma as a result of the high temperature and pressure. The molten magma, being less dense than the surrounding aesthenosphere, rises through the cracks of the Earth’s surface. As it rises through the surface, more silica is assimilated. The silica-rich is viscous and solidifies near the vent. It also is gas-rich as it traps gases. Hence, pressure builds up. Once the volcano can no longer contain the pressure, the volcano erupts violently, resulting in a VEI of 6.
The volcanic eruption of Mount Pinatubo had a lower death toll (853) than the volcanic eruption of Nevado Del Ruiz (23000) despite it having a larger VEI. Though both countries had predicted the volcanic eruptions, only the Phillipine government acted on it and swiftly evacuated the citizens. On the other hand, the Colombian government urged the citizens to remain where they were as they did not want to falsely alarm the citizens. Furthermore, there were no trained volcanologists monitoring the volcano to advise the government into taking swift action.
The volcanic eruption of Mount Merapi caused a death toll of 353. One of the factors that contributed to the death toll was the lack of the civilians’ corporation. Some returned to their village from the emergency shelter to tend to their crops and livestocks. Others did not leave the village due to cultural reasons. They believed that as long as the gatekeeper of Mount Merapi was alive, the volcano would not erupt.
The volcanic eruption of Mount St. Helens has a lower death toll (57) than the eruption of Nevado Del Ruiz (23000). Population density had a part in the disparity of the number of deaths. There were few people living near Mount St. Helens. However for Nevado Del Ruiz, the town of Armero was wiped out by the fast-flowing lahar. Other towns such as Chinchina were partially wiped out. These towns were densely populated and located near the volcano probably because agriculture was their livelihood. This is especially in Colombia, an LDC where the economy depends on the primary sector.