June 6, 1912 dawned clear and calm. Residents of the area were busy getting ready for the upcoming fishing season, but for at least a week people had felt earthquakes. Earthquakes are common in Alaska, a region long known for geologic instability, but people living and working in what would later become Katmai National Park and Preserve noticed that these earthquakes were unusually frequent and getting stronger. These earthquakes had prompted the two remaining families at Katmai Village to evacuate their homes two days earlier. They were wise to do so. Around 1 PM on June 6, the skies darkened over Katmai and for the next 60 hours the sun disappeared. The greatest eruption of the 20th century had begun.
Size and Impacts
In total, 3.1 mi3 (13 km3) of magma exploded out of the earth at Novarupta. This is 30 times more magma than the 1980 eruption of Mount St. Helens. Ash soared to over 100,000 ft (32 km) into the atmosphere. Kodiak Island, downwind of the ash cloud, was plunged into a darkness that lasted nearly three full days and the ash cloud eventually encircled the earth.
The summit of Mount Katmai, some 6 miles (10 km) distant from Novarupta collapsed as magma was drained from underneath it and vented at Novarupta. The former site of Mount Katmai’s summit is now occupied by a 1.9 mi (3 km) wide and 2000 ft (600 m) deep caldera.
The full story and mechanisms of the eruption are not fully understood. Still, an expansive scientific literature exists on this eruption and the Valley of Ten Thousand Smokes, and it is now one of the most intensively studied eruptions in the world. The Novarupta-Katmai Eruption of 1912—Largest Eruption of the Twentieth Century: Centennial Perspectives and Alaska Park Science: Volcanoes of Katmai and the Alaska Peninsula are two great sources for more information.
Valley of Ten Thousand Smokes
Our feeling of admiration [for the Valley] soon gave way to one of stupefaction. We were overawed. For a while we could neither think nor act in a normal fashion.”
Griggs had discovered a transformed Ukak River valley. This was a place once covered in shrubs and tundra and frequently traveled by Alutiiq people. It was changed in a matter of hours into a steaming mass of pumice and ash that Griggs named, “The Valley of Ten Thousand Smokes.”
The 1912 eruption’s pyroclastic flows and surges filled the Valley with thick deposits of hot ash and pumice. Buried snow fields and glacial streams flashed into steam as well as any subsequent rain and snow melt that seeped into the pumice fields. For years after the eruption, thousands of fumaroles (volcanic steam and gas vents) shot into the sky.
Griggs and his team thought the fumaroles were permanent features tied to a shallow magma chamber. In time, Griggs thought they would rival the geysers of Yellowstone National Park. So convinced of the Valley’s uniqueness and it’s scientific significance, Griggs and the National Geographic Society lobbied to protect the area. Largely because of their efforts, Katmai National Monument was created by presidential proclamation in 1918. Griggs’ account of discovery and exploration of the Valley is well documented in his 1922 book, The Valley of Ten Thousand Smokes.
By the 1930s most of the fumaroles had cooled as the residual heat trapped within the pyroclastic flow and surge deposits dissipated. Today, deposits from the former fumaroles paint the surface of the Valley of Ten Thousand Smokes.
Last updated: June 22, 2020