Novarupta is a

volcano A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most oft ...

located on the

Alaska Peninsula The Alaska Peninsula (also called Aleut Peninsula or Aleutian Peninsula, ; Sugpiaq language, Sugpiaq: ''Aluuwiq'', ''Al'uwiq'') is a peninsula extending about to the southwest from the mainland of Alaska and ending in the Aleutian Islands. T ...

on a slope of Trident Volcano in

Katmai National Park and Preserve Katmai National Park and Preserve is a List of national parks of the United States, United States national park and National preserve, preserve in southwest Alaska, notable for the Valley of Ten Thousand Smokes and for its Alaska Peninsula brown ...

, about southwest of

Anchorage Anchorage, officially the Municipality of Anchorage, is the most populous city in the U.S. state of Alaska. With a population of 291,247 at the 2020 census, it contains nearly 40 percent of the state's population. The Anchorage metropolita ...

. Novarupta was formed in 1912, during the largest volcanic eruption of the 20th century, in which it released 30 times the volume of

magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma (sometimes colloquially but incorrectly referred to as ''lava'') is found beneath the surface of the Earth, and evidence of magmatism has also ...

of the

1980 eruption of Mount St. Helens In March 1980, a series of volcanic explosions and pyroclastic flows began at Mount St. Helens in Skamania County, Washington, United States. A series of Phreatic eruption, phreatic blasts occurred from the summit and escalated until a major ...

Eruption of 1912

The 1912 eruption that formed Novarupta was the largest to occur during the 20th century. It began on June 6, 1912, and culminated in a series of violent eruptions. Rated a 6 on the

volcanic explosivity index The volcanic explosivity index (VEI) is a scale used to measure the size of explosive volcanic eruptions. It was devised by Christopher G. Newhall of the United States Geological Survey and Stephen Self in 1982. Volume of products, eruption c ...

, the 60-hour-long eruption expelled of ash, thirty times as much as the 1980 eruption of Mount St. Helens. The erupted magma of

rhyolite Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture (geology), texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained matri ...

dacite Dacite () is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides. It has a fine-grained (aphanitic) to porphyritic texture and is intermediate in composition between andesite and rhyolite. ...

, and

andesite Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predomina ...

Wood, C.A. and Kienle, J. (editors) (1990) ''Volcanoes of North America: United States and Canada'', Cambridge, Cambridge University Press, , p. 70. resulted in more than of air fall

tuff Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock co ...

and approximately of pyroclastic ash-flow tuff. During the 20th century, only the 1991 eruption of Mount Pinatubo in the

Philippines The Philippines, officially the Republic of the Philippines, is an Archipelagic state, archipelagic country in Southeast Asia. Located in the western Pacific Ocean, it consists of List of islands of the Philippines, 7,641 islands, with a tot ...

and the 1902 eruption of Santa María in

Guatemala Guatemala, officially the Republic of Guatemala, is a country in Central America. It is bordered to the north and west by Mexico, to the northeast by Belize, to the east by Honduras, and to the southeast by El Salvador. It is hydrologically b ...

were of comparable magnitude;

Mount Pinatubo Mount Pinatubo is an active stratovolcano in the Zambales Mountains in Luzon in the Philippines. Located on the tripoint of Zambales, Tarlac and Pampanga provinces, most people were unaware of its eruptive history before the pre-eruption volc ...

ejected of

tephra Tephra is fragmental material produced by a Volcano, volcanic eruption regardless of composition, fragment size, or emplacement mechanism. Volcanologists also refer to airborne fragments as pyroclasts. Once clasts have fallen to the ground, ...

, and Santa María just slightly less. At least two larger eruptions occurred in the

Dutch East Indies The Dutch East Indies, also known as the Netherlands East Indies (; ), was a Dutch Empire, Dutch colony with territory mostly comprising the modern state of Indonesia, which Proclamation of Indonesian Independence, declared independence on 17 Au ...

(now

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...

) during the 19th century: the 1815 eruption of Tambora ( of tephra) and the

1883 eruption of Krakatoa Beginning on 20 May 1883, and ending on 21 October 1883, the volcanic island of Krakatoa, located in the Sunda Strait, had repeated, months long Types of volcanic eruptions, volcanic eruptions. The most destructive of these eruptions occurred o ...

( of tephra). The Novarupta eruption occurred about from the peak of Mount Katmai Volcano and below the post-eruption Mount Katmai summit. During the eruption a large quantity of

erupted from beneath the Mount Katmai area, resulting in the formation of a wide, funnel-shaped vent and the collapse of Mount Katmai's summit, creating a deep,

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption. An eruption that ejects large volumes of magma over a short period of time can cause significant detriment to the str ...

. The eruption ended with the extrusion of a

lava dome In volcanology, a lava dome is a circular, mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano. Dome-building eruptions are common, particularly in convergent plate boundary settings. Around 6% of eruptions ...

that plugged the vent. The high and wide dome it created forms what is now referred to as Novarupta. Despite the magnitude of the eruption, no deaths directly resulted. Eyewitness accounts from people located downwind in the path of a thick ash cloud described the gradual lowering of visibility to next to nothing. Ash threatened to contaminate drinking water and destroyed food resources, but the

Alaska Native Alaska Natives (also known as Native Alaskans, Alaskan Indians, or Indigenous Alaskans) are the Indigenous peoples of the Americas, Indigenous peoples of Alaska that encompass a diverse arena of cultural and linguistic groups, including the I ...

s were aided in their survival by traditional knowledge passed down through generations from previous eruptions. However, the Native villages experiencing the heaviest ash falls were abandoned and the inhabitants relocated.

Valley of Ten Thousand Smokes

Pyroclastic flows from the eruption formed the Valley of Ten Thousand Smokes, named by botanist Robert F. Griggs, who explored the volcano's aftermath for the

National Geographic Society The National Geographic Society, headquartered in Washington, D.C., United States, is one of the largest nonprofit scientific and educational organizations in the world. Founded in 1888, its interests include geography, archaeology, natural sc ...

in 1916. The eruption that formed the Valley of Ten Thousand Smokes is one of the few in recorded history to have produced welded tuff, resulting in numerous fumaroles that persisted for 15 years. Colorful ash Valley of Ten Thousand Smokes

Colorful ash Valley of Ten Thousand Smokes

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 southwest of Anchorage. The area was originally designated a

National Monument A national monument is a monument constructed in order to commemorate something of importance to national heritage, such as a country's founding, independence, war, or the life and death of a historical figure. The term may also refer to a sp ...

in 1918 to protect the area around the 1912 eruption of Novarupta and the , deep, pyroclastic flow of the Valley of Ten Thousand Smokes.

Notes

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External links