Eruption of Mount Pinatubo

In all, the eruption ejected about ten cubic kilometres (2.5 mile³) of material, making it the largest eruption since that of Novarupta in 1912 and some ten times larger than the 1980 eruption of Mount St. Helens. Ejected material such as tephra fallout and pyroclastic flow deposits are much less dense than magma, and the volume of ejected material was equivalent to about four cubic kilometres (1 mile³) of unerupted material. This colossal eruption had a Volcanic Explosivity Index of 6. The former summit of the volcano was replaced by a caldera 2.5 km wide. The highest point on the caldera rim now stood 1,485 m above sea level, some 260 m lower than the pre-eruption summit.

Over 800 people were killed by the eruption, mostly by roofs collapsing under the weight of accumulated wet ash, a hazard that was greatly exacerbated by the simultaneous arrival of Typhoon Yunya. The evacuation in the days preceding the eruption certainly saved tens of thousands of lives, and has been hailed as a great success for volcanology and eruption prediction.

http://en.wikipedia.org/wiki/Mount_Pinatubo#199...