Griggs volcano overlooks Valley of Ten Thousand Smokes filled by ash in 1912 eruption of Katmai, Katmai Volcano National Park, Alaska, USA, North America

Valley of Ten Thousand Smokes with ignimbrite of 1912 eruption, Griggs volcano behind, Katmai National Park, Alaska, USA, North America

Ignimbrite exposed in river canyons cut since 1912 eruption, in the Valley of Ten Thousand Smokes, in Katmai Volcano National Park, Alaska, United States of America, North America

A man looks toward Trident Volcano through clouds while ascending the Knife Creek Glaciers in Katmai National Park; Alaska, United States of America

A backpacker crosses the exotic landscape of the ash and pumice-covered Valley of Ten Thousand Smokes in Katmai National Park, with Mt. Katmai (left), Trident Volcano (right), and the Knife Creek Glaciers looming in the distance; Alaska, United States of

Trident Volcano rises above the rugged ash-covered Knife Creek Glaciers in Katmai National Park; Alaska, United States of America

The eastern peak of Trident Volcano rises above the ash-covered Knife Creek Glaciers at sunset in Katmai National Park; Alaska, United States of America

A man is dwarfed by the jagged, ash-covered Knife Creek Glaciers and Trident Volcano in the Valley of Ten Thousand Smokes in Katmai National Park; Alaska, United States of America

Trident Volcano rises above the ash-covered Knife Creek Glaciers at sunset in Katmai National Park; Alaska, United States of America