volcano, western Luzon, Philippines, that erupted in 1991 (for the first time in 600 years) and caused widespread devastation. Mount Pinatubo is located about 55 miles (90 km) northwest of Manila and rose to a height of about 4,800 feet (1,460 m) prior to its eruption. After two months of emissions and small explosions, a series of major explosions began on June 12. These explosions reached a peak on June 14–16, producing a column of ash and smoke more than 19 miles (30 km) high, with rock debris falling the same distance from the volcano. The resulting heavy ashfalls left about 100,000 people homeless, forced thousands more to flee the area, and caused 300 deaths. The ashfalls forced the evacuation and eventual closing of U.S.-leased Clark Air (Clark Air Base) Force Base, 10 miles (16 km) east of the volcano.

The ash and smoke cloud ejected by Mount Pinatubo in 1991 contained about twice as much matter as that thrown up by the El Chichón volcano (1982), making Pinatubo perhaps the largest eruption of the 20th century. Pinatubo erupted again in late August 1992, killing more than 72 people.