Mount Pinatubo is a volcano located on
the island of Luzon in the Philippines. Nestled in the central part of the
Zambales mountain range, the volcano lies 55 miles northwest of the capital
city of Manila.
After lying dormant for almost 500
years, the volcano's eruption in June 1991 resulted in one of the most
destructive volcanic eruptions of the 20th century.
Thick deposits of tephra, streams of
pyroclastic flow, and lahars caused significant damage to the economy and
infrastructure of surrounding cities.
The volcano also ejected millions of
tons of sulfur dioxide into the atmosphere, which contributed to ozone
depletion and caused a worldwide decrease in temperature.
Before the eruption, Mount Pinatubo was covered with tropical vegetation
and was home to more than 30,000 people who lived in villages on its slopes. Thousands of other people lived in
the valleys surrounding the volcano, including US military personnel stationed at Clark Air Base and Subic Bay
Naval Station. Scientists from the Philippine Institute of Volcanology and Seismology (PHIVOLCS) and the United
States Geological Survey (USGS) were able to accurately predict the timing of the eruption and its effects. As a
result, the Philippine government and the American military were able to carry out a timely evacuation of the
population, saving thousands of lives and millions of dollars in property damage. However, the eruption killed
up to 800 people and displaced thousands more by burying the surrounding land with thick layers of ash. Dams
were built to control destructive lahars that followed the eruption, and recovery costs totaled billions of
The volcano's eruption also had significant global environmental effects.
Mount Pinatubo ejected millions of tons of sulfur dioxide gas into the atmosphere, forming a cloud over the earth
and decreasing average worldwide temperatures by almost 1 degree Fahrenheit for several years after the eruption.
The sulfur dioxide, which mixed with water and oxygen in the atmosphere to create sulfuric acid, also contributed
to a rapid destruction of ozone. The ozone layer hole over Antarctica reached its largest size when observed the
year following the eruption.