thumb|Griggs camp during the 1916 expedition clearly showing the numerous "smokes"

thumb|Knife Creek Gorge

The Valley of Ten Thousand Smokes is a valley within Katmai National Park and Preserve in Alaska which is filled with ash flow from the eruption of Novarupta on June 6–8, 1912. Following the eruption, thousands of fumaroles vented steam from the ash. Robert F. Griggs, who explored the volcano's aftermath for the National Geographic Society 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."

Prior to the eruption, the area now called the Valley of Ten Thousand Smokes was an unremarkable and unnamed portion of the Ukak River valley. Although never permanently inhabited by humans, it served as a pass for the Alutiiq people, as well as animals such as grizzly bears.

The 1912 eruption was the largest eruption by volume in the 20th century, erupting a magma volume of about . As many as 14 major earthquakes between <math>M_\text{s}</math> 6 to 7, and over 100 earthquakes greater than <math>M_\text{s}</math> 5, resulted from the collapse of the caldera at Mount Katmai and movement within the magmatic plumbing system.

thumb|left|River eroding volcanic ash flow, Valley of Ten Thousand Smokes

thumb|[[Canyon cut in ash by River Lethe]]

The ash-filled valley covers a area. In places deep canyons have been cut by the River Lethe, allowing observers to see the ash flow strata. Since the ash has cooled, most of the fumaroles are now extinct and despite its name the valley is no longer filled with 'smoke' (i.e. steam). Vegetation still does not grow in the valley. The signs of volcanic activity are still visible on nearby hills.

Katmai's most recent eruption was in 1927, but there have been non-eruptive events as recently as 2003. The Alaska Volcano Observatory still monitors Katmai's activity as part of the Katmai Cluster, where there are five active stratovolcanos within of Katmai.

Visitors to the valley most commonly arrive via bus along the road from Brooks Camp, which is the only road in Katmai Park. The valley is a source of creative exploration by photographers and naturalists.

Geology

Basement rocks in the area consist of the Late Jurassic Naknek Formation, which is composed of siltstones, and arkosic sandstones 1.7–2&nbsp;km thick deposited in a marine shelf and submarine fan delta environment during the Oxfordian-Tithonian. Some 20 dioritic and granodioritic Tertiary plutons pierce the formation. Most prevalent though are the Quaternary stratovolcanoes along the Aleutian Arc associated with the Aleutian subduction zone.

References

  • Alaska Volcano Observatory page on Katmai
  • Maps of region