Alaska, United States
Novarupta, meaning "new eruption", is a volcano located on the Alaska Peninsula in Katmai National Park and Preserve, about 290 miles southwest of Anchorage. Formed in 1912 during the largest volcanic eruption of the 20th century, Novarupta released 30 times the volume of magma as the 1980 eruption of Mount St. Helens.
Eruption of 1912
The largest eruption of the 20th century occurred in 1912, from June 6 to June 8, to form Novarupta. Rated a 6 on the volcanic explosivity index, the 60 hour long eruption expelled 13 to 15 kilometers of magma, 30 times as much as the 1980 eruption of Mount St. Helens. The erupted magma resulted in more than 17 kilometers of air fall and approximately 11 kilometers of ash-flow tuff Only the 1991 eruption of Mt. Pinatubo in the Philippines was of a similar magnitude during the 20th century, ejecting 11 kilometers of tephra.
At least two larger eruptions occurred in the 19th century: the 1815 eruption of Tambora (150 kilometers of tephra) and the 1883 eruption of Indonesia's Krakatoa (20 kilometers
Eruption of such a large quantity of magma from underneath the Mount Katmai area resulted in the formation of a 2 kilometers wide funnel shaped vent and the collapse of the summit of Mount Katmai creating a 600 meters deep, 3 by 4 kilometers caldera.
The eruption ended with the extrusion of a lava dome that plugged the vent. The 295 feet high and 1180 feet wide dome is what is now referred to as Novarupta.
Valley of Ten Thousand Smokes
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.
The eruption forming of the Valley of Ten Thousand Smokes is one of the few in recorded history to have produced welded tuff, producing numerous fumaroles that persisted for 15 years.
Katmai National Park
Established as a National Park & Preserve in 1980, Katmai is located on the Alaska Peninsula, across from Kodiak Island, with headquarters in nearby King Salmon, about 290 miles southwest of Anchorage. The area was originally designated a National Monument in 1918 to protect the area around the major 1912 volcanic eruption of Novarupta and the 40 square miles, 100 to 700 feet deep, pyroclastic flow of the Valley of Ten Thousand Smokes.