What was the largest volcanic eruption of the 20th century? Perhaps Mount St. Helens in 1980 or maybe Mount Pinatubo in 1991? The answer is actually Novarupta, a volcano that erupted in 1912 and was three times the size of the Pinatubo eruption and 30 times larger than Mount St. Helens.
The volcano is relatively unknown because of its remote location in southern Alaska, and that also means that the imagery of the area isn’t especially great. However, the NASA Earth Observatory just released an excellent image that was captured in August, 2002, that gives us a great look at the volcano.
The eruption was so massive that dust was found as far away as Puget Sound, Washington, and the ash from the volcano circled the globe and caused lower global temperatures for a year.
You can view this image for yourself inside of Google Earth by using this KML file or you can read more about the eruption on the NASA Earth Observatory site.