During the eruption a large quantity of magma erupted from beneath the Mount Katmai area, resulting in the formation of a 1.2-mile (2 km) wide, funnel-shaped vent and the collapse of Mount Katmai's summit, creating a 2,000-foot (600 m) deep,[7] 1.9 by 2.5 mi (3 by 4 km) caldera.

[17]: 3 [18] Eyewitness accounts from people located downwind in the path of a thick ash cloud described the gradual lowering of visibility to next to nothing.

[19] Ash threatened to contaminate drinking water and destroyed food resources, but the Alaska Natives were aided in their survival by traditional knowledge passed down through generations from previous eruptions.

[19] Pyroclastic flows 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.

[21] 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.