Novarupta

Novarupta
Novarupta's lava dome in July 1987.
Highest point
Elevation
Coordinates
Geography
Location	Katmai National Park and Preserve, Alaska, U.S.
Parent range	Aleutian Range
Topo map	USGS Mount Katmai B-4
Geology
Mountain type	Caldera with lava dome
Volcanic arc/belt	Aleutian Arc
Last eruption	June to October 1912

Novarupta (Russian: Вулкан Новарупта, literally "new eruption") is a new volcano that was created in 1912, located on the Alaska Peninsula in Katmai National Park and Preserve, about southwest of Anchorage. Formed during the largest volcanic eruption of the 20th century, Novarupta released 30 times the volume of magma of the 1980 eruption of Mount St. Helens.

Map showing volcanoes of the Alaska Peninsula

Eruption of 1912

1912 eruption of Novarupta
Volcano	Novarupta
Date	June 6–8, 1912
Type	Ultra Plinian
Location	Aleutian Range, Alaska
VEI	6.2

The eruption of Novarupta within the Aleutian Range began on June 6, 1912, and culminated in a series of violent eruptions from the original Novarupta volcano. Rated a 6 on the Volcanic Explosivity Index, the 60-hour-long eruption expelled 13 to 15 cubic kilometers (3.1 to 3.6 cu mi) of ash, 30 times as much as the 1980 eruption of Mount St. Helens. The erupted magma of rhyolitic, dacitic, and andesitic composition resulted in more than 17 cubic kilometers (4.1 cu mi) of air fall tuff and approximately 11 cubic kilometers (2.6 cu mi) of pyroclastic ash-flow tuff. During the 20th century, only the 1991 eruption of Mt. Pinatubo in the Philippines was of a similar magnitude; Pinatubo ejected 11 cubic kilometers (2.6 cu mi) of tephra. At least two larger eruptions occurred in the 19th century: the 1815 eruption of Tambora (150 km³ (36.0 cu mi) of tephra) and the 1883 eruption of Indonesia's Krakatoa (20 km³ (4.8 cu mi) of tephra).

Novarupta occurred about 2.5 miles from the peak of volcanic Mount Katmai and 4,000 feet below the post-eruption summit of Mount Katmai. During the eruption a large quantity of magma was removed from underneath the Mount Katmai area, resulting in the formation of a 2-kilometer (1.2 mi) wide, funnel-shaped vent and the collapse of Mount Katmai's summit, creating a deep, 3 by 4 km (1.9 by 2.5 mi) caldera.

The eruption ended with the extrusion of a lava dome of rhyolite that plugged the vent. The 295-foot (90 m) high and 1,180-foot (360 m) wide dome and the caldera it created form what is now referred to as Novarupta.

Despite the magnitude of the eruption, no deaths directly resulted.

Valley of Ten Thousand Smokes

Main article: Valley of Ten Thousand Smokes

File:Colorful ash Valley of Ten Thousand Smokes.jpg

Colorful ash in the Valley of Ten Thousand Smokes

Pyroclastic ash flow 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 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

Main article: Katmai National Park and Preserve

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 mi (470 km) southwest of Anchorage. The area was originally designated a National Monument in 1918 to protect the area around the 1912 eruption of Novarupta and the 40-square-mile (104 km²), deep, pyroclastic flow of the Valley of Ten Thousand Smokes.

See also

• List of volcanoes in the United States
• Timeline of volcanism on Earth
• Parícutin, a cinder cone volcano in Mexico whose emergence could be fully observed.

External links

• USGS collection of descriptions of Novarupta
• USGS QuickTime video clip on Novarupta (36 seconds/0.8 MB)
• geology.com, Novarupta – topographic maps, annotated satellite images
• Alaska Volcano Observatory: Novarupta
• USGS Photographic Library – novarupta

• Wood, C.A. and Kienle, J. (editors) (1990) Volcanoes of North America: United States and Canada, Cambridge, Cambridge University Press, ISBN 0-521-36469-8, page 70.