Final answer:
The eruption of Mount St. Helens in 1980 resulted in the eruption of approximately 0.67 cubic miles of rock and ash from the volcano.
Step-by-step explanation:
The eruption of Mount St. Helens in 1980 resulted in the eruption of approximately 0.67 cubic miles (2.8 cubic kilometers) of rock and ash from the volcano. The eruption was triggered by an earthquake, which caused a massive landslide on the north flank of the volcano, followed by an explosive blast of hot gas and rock fragments, volcanic ash, and mudflows. The eruption significantly altered the landscape and resulted in the death of 57 people.