Valley of Ten Thousand Smokes
Encyclopedia
Valley
In geology, a valley or dale is a depression with predominant extent in one direction. A very deep river valley may be called a canyon or gorge.The terms U-shaped and V-shaped are descriptive terms of geography to characterize the form of valleys...
within Katmai National Park and Preserve
Katmai National Park and Preserve
Katmai National Park and Preserve is a United States National Park in southern Alaska, notable for the Valley of Ten Thousand Smokes and for its brown bears. The park covers , being roughly the size of Wales. Most of this is a designated wilderness area, including of the park...
in Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
which is filled with ash
Volcanic ash
Volcanic ash consists of small tephra, which are bits of pulverized rock and glass created by volcanic eruptions, less than in diameter. There are three mechanisms of volcanic ash formation: gas release under decompression causing magmatic eruptions; thermal contraction from chilling on contact...
flow from the eruption of Novarupta
Novarupta
Novarupta, meaning "new eruption", is a volcano located on the Alaska Peninsula in Katmai National Park and Preserve, about 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...
on June 6–8, 1912. Following the eruption, thousands of fumarole
Fumarole
A fumarole is an opening in a planet's crust, often in the neighborhood of volcanoes, which emits steam and gases such as carbon dioxide, sulfur dioxide, hydrochloric acid, and hydrogen sulfide. The steam is created when superheated water turns to steam as its pressure drops when it emerges from...
s vented steam
Steam
Steam is the technical term for water vapor, the gaseous phase of water, which is formed when water boils. In common language it is often used to refer to the visible mist of water droplets formed as this water vapor condenses in the presence of cooler air...
from the ash. Robert F. Griggs
Robert F Griggs
Robert Fiske Griggs, , was a botanist who led a 1915 National Geographic Society expedition to observe the aftermath of the Katmai volcanic eruption....
, who explored the volcano
Volcano
2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...
's aftermath for the National Geographic Society
National Geographic Society
The National Geographic Society , headquartered in Washington, D.C. in the United States, is one of the largest non-profit scientific and educational institutions in the world. Its interests include geography, archaeology and natural science, the promotion of environmental and historical...
in 1916, gave the valley its name, saying that "the whole valley as far as the eye could reach was full of hundreds, no thousands—literally, tens of thousands—of smokes curling up from its fissured floor."
The 1912 eruption was the largest eruption by volume
Volume
Volume is the quantity of three-dimensional space enclosed by some closed boundary, for example, the space that a substance or shape occupies or contains....
in the 20th century, erupting about 13 cubic kilometres (3.1 cu mi) of material. Novarupta generated as many as 14 major earthquakes with magnitudes
Richter magnitude scale
The expression Richter magnitude scale refers to a number of ways to assign a single number to quantify the energy contained in an earthquake....
between M6 and M7, a level of energy
Energy
In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...
release virtually unprecedented during volcanic eruptions in modern memory, and over 100 earthquakes greater than M5. Following the eruption, the summit of Mount Katmai
Mount Katmai
Mount Katmai is a large stratovolcano on the Alaska Peninsula in southern Alaska, located within Katmai National Park and Preserve. It is about in diameter with a central lake-filled caldera about 3 by 2 mi in area, formed during the Novarupta eruption of 1912. The caldera rim reaches a...
subsided (collapsed) about 1200 metres (3,937 ft), forming the central caldera
Caldera
A caldera is a cauldron-like volcanic feature usually formed by the collapse of land following a volcanic eruption, such as the one at Yellowstone National Park in the US. They are sometimes confused with volcanic craters...
.
Katmai is a stratovolcano
Stratovolcano
A stratovolcano, also known as a composite volcano, is a tall, conical volcano built up by many layers of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile and periodic, explosive eruptions...
, formed from alternating layers of lava flows and pyroclastic rocks. The presence of pyroclastic materials indicates that some Katmai eruptions have been explosive. The subsidence of the summit to form the central caldera
Caldera
A caldera is a cauldron-like volcanic feature usually formed by the collapse of land following a volcanic eruption, such as the one at Yellowstone National Park in the US. They are sometimes confused with volcanic craters...
and the extraordinarily energetic earthquakes accompanying the 1912 eruption are evidence of this.
River Lethe
River Lethe is located 18 km west of Mount Katmai, Alaska Peninsula, and is the middle branch of the Ukak River. It flows through the Valley of Ten Thousand Smokes and meets the Ukak at ....
, allowing observers to see the ash flow strata
Stratum
In geology and related fields, a stratum is a layer of sedimentary rock or soil with internally consistent characteristics that distinguish it from other layers...
. Since the ash has cooled, most of the fumaroles are now extinct and despite its name the valley is no longer filled with smoke. The signs of volcanic activity are still visible on nearby hill
Hill
A hill is a landform that extends above the surrounding terrain. Hills often have a distinct summit, although in areas with scarp/dip topography a hill may refer to a particular section of flat terrain without a massive summit A hill is a landform that extends above the surrounding terrain. Hills...
s. Katmai's most recent eruption was in 1927, but there have been non-eruptive events as recent as 2003. The Alaska Volcano Observatory
Alaska Volcano Observatory
The Alaska Volcano Observatory is a joint program of the United States Geological Survey, the Geophysical Institute of the University of Alaska Fairbanks, and the State of Alaska Division of Geological and Geophysical Surveys...
still monitors Katmai's activity as part of the Katmai Cluster, where there are 5 active stratovolcanos within 15 kilometres (9 mi) of Katmai.
Visitors to the valley most commonly arrive via bus along the 20 miles (32 km) road from Brooks Camp, which is the only road in Katmai Park.