Fisher Caldera facts for kids

Fisher Caldera, also known as Mount Fisher, is a huge bowl-shaped hollow on Unimak Island in Alaska. This large volcanic caldera is about 11 kilometers (7 miles) wide and 18 kilometers (11 miles) long. It's found in the Aleutian Islands, a chain of islands in Alaska.

This caldera was formed by a powerful volcanic eruption that happened about 9,100 years ago. Inside Fisher Caldera, you can find three crater lakes. One lake is about 2 miles (3.2 kilometers) wide, and the other two are about 1.5 miles (2.4 kilometers) wide. There are also some small peaks inside the caldera, reaching heights of about 600 meters (1,969 feet) and 619 meters (2,031 feet). Fisher Caldera is quite close to another volcano, Mount Westdahl, being only about 13 miles (21 kilometers) away.

The Giant Eruption

Fisher Caldera was the site of the biggest volcanic eruption on Earth during the Holocene Epoch. The Holocene Epoch is the name for the last 11,700 years of Earth's history. This massive eruption happened around 8700 BCE. It was so powerful that it caused the top of a large stratovolcano to collapse, forming the caldera we see today.

What is a Caldera?

A caldera is a large, bowl-shaped hollow that forms when the ground collapses after a huge volcanic eruption. Imagine a volcano erupting so violently that it empties the magma chamber beneath it. Without the support of the magma, the ground above the chamber can no longer hold itself up and falls inward, creating a large depression.

What is a Stratovolcano?

A stratovolcano is a tall, cone-shaped volcano. It is built up by many layers of hardened lava, ash, and rocks from past eruptions. These volcanoes are known for their explosive eruptions. The volcano that formed Fisher Caldera was once a stratovolcano.