Mount Pinatubo is a large volcano in the Philippine islands.  It stands 5,770 feet (1760 m) tall in the middle of a three-mile wide depression. 

On June 15, 1991, it erupted for the first time in 600 years.  The eruption blasted 25 miles (40 kilometers) of sulfur dioxide into the air.

Mount Pinatubo Erupting.  Photo Credit: Bethany Burum.

A gigantic cloud mixed with water vapor and circled around the planet in three weeks.  It caused temporary temperature decreases by blocking out 2% of all the sunlight the Earth received.

The explosion will have harmful effects on the ozone layer.  Sulfur dioxide particles entered the stratosphere after the eruption, and will deplete the ozone layer for many years into the future.

Mount Pinatubo is one of thirteen active volcanoes on the Philippine island of Luzon.  Many other volcanoes are located along the same plate of the earth, and form what is known as the Ring of Fire.

Several events preceding the eruption indicated that it was coming.  There were steam eruptions, earthquakes, sulfur dioxide emissions, and even minor explosions before the volcano erupted.

Despite the early warning, 900 people were killed by the volcano.  However, many more would certainly have died had it not been for the predictions.  200,000 were moved, and 42,000 homes were destroyed.  The Philippines lost over US $1 billion as a result of the explosion, and many people continue to suffer from its effects.

Encarta on Mount Pinatubo

Information on the mountain