 |
| Novarupta eruption |
Today, The Grandma has gone to the library to search more information about Novarupta volcano in Alaska. The Grandma loves volcanoes and she is interested in this volcano because it is considered the largest volcanic eruption of the 20th century.
Novarupta erupted on a day like today in 1912 and today is an excellent moment to remember that event.
Novarupta, meaning newly erupted in Latin, is a volcano that was formed in 1912, located on the Alaska Peninsula in Katmai National Park and Preserve, about 470 km 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.
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 60-hour-long eruption expelled 13 to 15 km3 of ash, thirty times as much as the 1980 eruption of Mount St. Helens.
The erupted magma of rhyolite, dacite, and andesite resulted in more than 17 km3 of air fall tuff and approximately 11 km3 of pyroclastic ash-flow tuff. During the 20th century, only the 1991 eruption of Mount Pinatubo in the Philippines and the 1902 eruption of Santa María in Guatemala were of comparable magnitude; Pinatubo ejected 11 km3, and Santa María just slightly less.
 |
| Novarupta eruption |
At least two larger eruptions occurred in the Dutch East Indies, now Indonesia, during the 19th century: the 1815 eruption of Tambora 150 km3 of tephra and the 1883 eruption of Krakatoa 20 km3 of tephra.
The Novarupta eruption occurred about 4.0 km from the peak of Mount Katmai Volcano and 1,200 m below the post-eruption Mount Katmai summit. During the eruption a large quantity of magma erupted from beneath the Mount Katmai area, resulting in the formation of a 2 km wide, funnel-shaped vent and the collapse of Mount Katmai's summit, creating a 600 m deep, 3 by 4 km caldera.
The eruption ended with the extrusion of a lava dome of rhyolite that plugged the vent. The 90 m high and 360 m wide dome it created forms what is now referred to as Novarupta.
More information: Geology
Despite the magnitude of the eruption, no deaths directly resulted. Eye witness accounts from people located downwind in the path of a thick ash cloud describe the gradual lowering of visibility to next to nothing. Ash threatened to contaminate drinking water and decimate food resources, but the native Alaskans 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. The eruption is said to have had an effect on the level of the Nile.
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 that formed 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.
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 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 104 km2, 30 to 210 m deep, pyroclastic flow of the Valley of Ten Thousand Smokes.
More information: Wired
The thing that struck me most about the Mount St. Helens
project was not the devastation of the eruption,
but the logging industry -the earth
transformed on that scale by humans.
David Maisel
No comments:
Post a Comment