Volcano Explosivity Index

The recent eruption of the Eyjafjallajokull volcano in Iceland has had a huge  impact on the airline industry in Europe and across the globe. From a volcanic and geological standpoint the eruption was not nearly as massive.  Volcanic eruptions are measured using a scale called the “Volcanic Explosivity Index” or VEI for short. This scale runs from 0-8 in level of eruption magnitude. On the low end you would have eruptions like Mauna Loa in 1984 and Kilauea currently in Hawaii. The current Eyjafjallajokull volcano is a 4 magnitude and Mount St Helens in 1980 was a 5. The biggest eruption in the past 100 years was Mount Pinatubo in the Philippines in 1991 which was a VEI of 6 and actually cooled the earth by 1°F for an entire year after the eruption. There hasn’t been a volcano that has erupted in the 7-8  magnitude since Mount Tambora in 1815. 

The impacts on the global temperatures will be minor from the Eyjafjallajokull as well do to the relate small magnitude of the eruption and the latitude of the volcano. Research has shown that for an eruptions to have a significant impact on the short term climate it has to be a much lower latitude and have an ash plume that makes it into the Stratosphere. This is what happened with Mount Pinatubo in 1991 the ash plume soared to a higher well over 80-90,000 feet. This allows for the the ash to stay aloft above the Troposphere where all the weather happens for months and block out significant UV radiation from the sun. At these heights and latitude the ash will spread worldwide. High latitude volcanoes tend to only have their ahs circulate at these high latitudes and now have a global impact.