Novarupta, meaning "new eruption", is a volcano located on the Alaska Peninsula in the Katmai area, about 290 miles southwest of Anchorage. Novarupta sits below Mount Katmai. Its eruption of June 6–June 8, 1912, was ten times more powerful than the 1980 eruption of Mount St. Helens and led to the formation of this 841 m (2759 ft) volcano.
The 1912 Novarupta eruption was the largest volcanic eruption of the 20th century. About 15 km³ of volcanic material was ejected over two and a half days. The 1815 eruption of Tambora however, had displaced about seven times as much material. The 1883 eruption of Indonesia's Krakatoa displaced twice as much as Novarupta. Novarupta's 1912 eruption has been rated a 6 on the Volcanic Explosivity Index. Magma from underneath the Mount Katmai area was drained away to Novarupta, resulting in a collapsed 3 × 4 km caldera.


The lava dome that formed to plug the vent from which the eruption occurred is what is now referred to as Novarupta. Pyroclastic ash flow from the eruption formed what was named the Valley of Ten Thousand Smokes by botanist Robert F. Griggs, who explored the volcano's aftermath for the National Geographic Society in 1916. Katmai National Park and Preserve was formed to protect the area around Novarupta.