The largest volcanic eruption in the last 100 years, and the second-largest eruption of the 20th century, occurred on June 15, 1991. Mount Pinatubo, a stratovolcano located in the Luzon Volcanic Arc, has been an active volcanic site for over a million years. It has experienced well-documented explosive eruptions for more than 35,000 years, with two significant eruptions in the last century. The eruption on June 15, 1991, was cataclysmic, and its effects are still felt to this day.

In the years leading up to the 1991 eruption, Mount Pinatubo had been dormant for nearly 500 years. However, scientists from the Philippine Institute of Volcanology and Seismology were closely monitoring the site and observed an increase in volcanic activity in early 1991. They recorded rising magma levels and a continuous release of sulfur dioxide. By April 1991, small eruptions began to occur, accompanied by minor earthquakes in the surrounding area. On June 7, a lava dome appeared, signaling that a large eruption was imminent. A massive effort was made to evacuate people from a 40-kilometer radius surrounding the volcano. However, the eruption on June 15 was even larger than predicted, resulting in a significant loss of life and extensive damage.

Although nearly 20,000 people were evacuated in anticipation of the disaster, the eruption of Mount Pinatubo and the subsequent mudslides resulted in the deaths of nearly 900 individuals and caused hundreds of additional injuries. Entire villages were buried, leaving thousands homeless. The total financial losses and hardships are estimated to be in the billions of dollars. On a global scale, the eruption also had a significant impact. The enormous amount of ash released into the atmosphere caused a global cooling of 1.5 degrees Celsius, affecting weather patterns and the climate system as a whole. Mount Pinatubo erupted again in 1992, but on a much smaller scale. The effects of the 1991 eruption are still being felt today.