What Should I Know About Mt. Pinatubo?

Mount Pinatubo is a volcano located in the Philippine island of Luzon. It is classified as a stratovolcano, or composite volcano, made of andesite and dacite, and covered in a dense forest. The volcano's highlands were mostly populated by the Aeta, an indigenous tribal group. The volcano had been dormant for almost 500 years when it suddenly erupted in 1991. The Mount Pinatubo eruption is said to be one of the most violent volcanic calamities of the 20th century.

Mount Pinatubo's eruption was preceded by an earthquake with a magnitude of 7.8 in July 1990. The epicenter of the earthquake was located 62 miles (100 km) northeast of the volcano and it is speculated that this may have triggered the volcano's awakening. In March 1991, a slew of small earthquakes began to plague the Mount Pinatubo area and in April of that same year, phreatic eruptions occurred near the volcano's summit. These developments eventually led to a slew of major eruptions.

On 15 June 1991, an ash cloud ascended from the volcano, covering an area of a few thousand square miles. This ash cloud effectively blocked out the sun, rendering the mid-afternoon sky as dark as night across most of Central Luzon. Heavy ashfall from the volcano ultimately covered a land area of about 1,544 squares miles (4,000 square kilometers). A blanket of ash, which witnesses likened to snow, reached as far as Manila, the country's capital. Ashfall was also recorded in countries as far away as Vietnam, Cambodia and Malaysia.

To add to the disaster, a tropical typhoon struck the island on the very same day that Mount Pinatubo was fated to have its most climactic eruption. Although local scientists and representatives from the US Geological Survey were on hand to monitor these developments, and while many communities were successfully evacuated before the volcano's first major eruption, many lives were still lost. The combination of volcanic eruption and tropical typhoon was simply too powerful.

Those who had escaped the volcano's wrath were trapped by the anger of the storm, which billowed vast quantities of rocks, ash, and minerals around the area. Witnesses report that it seemed as if they had been caught in a rain of ash and boulders. Many roofs collapsed under the weight of this debris, killing the people under them - people who may have already been outside of the volcano's critical line, had the typhoon not struck.

Mount Pinatubo's violent eruption took the lives of over 500 people, displaced tens of thousands of families, and ravaged indigenous wildlife. A flow of lahar, ash, and other volcanic debris continues to cover a few affected areas. Mount Pinatubo also decimated billions of dollars in property and infrastructure and displaced over tens of thousands of families.

The effects of Mount Pinatubo does not stop there however, for the eruption made itself felt all around the globe. The volcano released over 5 billion cubic meters of ash and other pyroclastic matter into the environment and produced eruption columns reaching 18.64 miles (30 kilometers) into the air. The eruption also reduced the density of the ozone layer, which it achieved by injecting a large amount of aerosols into the stratosphere. The aerosols eventually formed a sulfuric acid haze around the globe, causing the world's temperature to drop by an average of 1.8 degrees Fahrenheit (1 degree Celsius).

The extraneous matter in the earth's atmosphere also provided the world with a slew of brilliant sunsets and sunrises.