1991 Eruption of Mount Pinatubo

The second-largest volcanic eruption of the 20th century, climaxing on 15 June 1991 after months of phreatic explosions and seismic unrest. The eruption sent an ash column about 40 kilometers into the atmosphere, collapsed the summit into a caldera, and injected enough sulfur dioxide into the stratosphere to cool global temperatures by about 0.5 degrees Celsius over the following two years; it is considered one of the best forecast major eruptions in history. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/