Novarupta Had the Most Powerful Eruption of the 20th Century

Neither Mount St. Helens nor any other recent eruptions can be considered the most intense volcanic explosion of the 20th century. This one was created in 1912 when the Novarupta volcano in Alaska erupted. Today's technology makes it simpler to predict when and where large eruptions may occur. In 1912, it was not the case. Additionally, due to Novarupta's isolation, not many people were aware of what was happening. People in Juneau, Alaska—about 750 miles away—were the last to learn about the eruption for about an hour after it started.

Around 7.2 cubic miles of material were released by Novarupta into the atmosphere, where they ultimately fell to the ground. In some ways, that exceeds the total number of previous eruptions in Alaska. Compared to Mount St. Helens, it was thirty times larger.

The inhabitants of the nearest island, 100 miles distant, were covered with ash for three days in a row. It dropped more than one foot deep and was so heavy that it toppled structures. It turned the sun black and prevented breathing. No outside life could endure it. Ash travelled so far that it was discovered in Africa after two weeks.

• Location: USA