Mount St. Helens Eruption Facts

Mount St. Helens, a dormant volcano in Washington, erupted in 1980 after over a century of inactivity. The eruption was triggered by a massive earthquake, leading to a lateral explosion with the force of 1,500 Hiroshima bombs. The eruption caused significant destruction, including a massive lahar and widespread ashfall, affecting areas up to 300 miles away. It was the deadliest volcanic event in US history, claiming 57 lives. Scientists faced challenges in observing the eruption due to the altered landscape and hazardous conditions.

What is the height of Mount St. Helens?

• 5,000 feet

• 10,000 feet

• 15,000 feet

• 20,000 feet

What happens when magma comes into contact with water beneath the Earth's surface?

• It cools down immediately

• It creates new land

• It causes a small earthquake

• It can lead to an explosive eruption

What type of eruption did scientists initially expect from Mount St. Helens?

• Vertical eruption

• Lateral eruption

• Underwater eruption

• No eruption

What triggered the massive eruption of Mount St. Helens?

• A volcanic storm

• A massive earthquake

• A meteor strike

• A landslide

How fast did the rock and gas travel during the eruption?

• 100 miles per hour

• 200 miles per hour

• 300 miles per hour

• 400 miles per hour

What is a lahar?

• A dense ash cloud

• A volcanic gas

• A type of volcanic rock

• A slurry of water, rock, and debris

What made navigation difficult for scientists after the eruption?

• Heavy rain

• Thick fog

• The ground no longer matched maps

• Strong winds

How far did the ash from Mount St. Helens travel?

• 400 miles

• 100 miles

• 200 miles

• 300 miles

How long did it take for the ash to circle the globe?

• One week

• Two weeks

• Three weeks

• Four weeks

How many lives were claimed by the eruption of Mount St. Helens?

• 77

• 57

• 67

• 47