Skip to main content
U.S. flag

An official website of the United States government

What was the largest volcanic eruption in the 20th century?

The world's largest eruption of the 20th century occurred in 1912 at Novarupta on the Alaska Peninsula in what is now Katmai National Park and Preserve. An estimated 15 cubic kilometers of magma was explosively erupted during 60 hours beginning on June 6th. This volume is equivalent to 230 years of eruption at Kilauea (Hawaii) or about 30 times the volume erupted by Mount St. Helens (Washington) in 1980!

Due to the remote location of the eruption, scientists did not visit the site until 1918, when they found the Ukak River valley filled with volcanic deposits and steaming fumaroles. They called it the "Valley of Ten Thousand Smokes".

Learn moreThe Novarupta-Katmai eruption of 1912 - largest eruption of the twentieth century; centennial perspectives

Related Content