Which Washington volcano erupted on May 18, 1980?

Which Washington volcano erupted on May 18, 1980? The answer is Mount St. Helens.

Mount St. Helens erupted catastrophically in southwestern Washington on May 18, 1980. At 8:32 a.m., a magnitude-5.1 earthquake triggered the collapse of the volcano’s unstable north flank, producing the largest known debris avalanche in recorded history and unleashing a devastating lateral blast.

The eruption rated 5 on the Volcanic Explosivity Index. Its ash column rose high into the atmosphere, while pyroclastic flows and lahars spread across surrounding valleys. The event killed 57 people and destroyed homes, bridges, railways, and highways. It also reduced the mountain’s summit elevation by about 1,300 feet and left a huge horseshoe-shaped crater.

The other options are active Cascade volcanoes, but they did not produce the famous May 18, 1980 eruption. Mount Rainier is Washington’s tallest peak, Mount Baker is heavily glaciated, and Glacier Peak is another remote volcanic mountain. Mount St. Helens remains an active volcano and experienced further eruptive activity after 1980.