Alaska's volcanic belt is part of the Pacific "Ring of Fire" and contains 70 potentially active volcanoes. It extends from Mount Spurr north of Lake Clark to Buldir Island in the western Aleutians. Within the Lake Clark region there are four active volcanoes. Mount Spurr, at 11,070 feet, lies just north of the park. Mount Redoubt, at 10,197 feet, and Mount Iliamna, at 10,016 feet, are both located in the park. To the south of the park lies Mt. Augustine.

Mount Spurr erupted on July 9, 1953. That spectacular explosion sent a cloud of ash up 70,000 feet in just 40 minutes, according to U.S. Air Force pilots who were flying in the area when the eruption occurred. Ash dropped on Anchorage, only 80 miles east, with a total accumulation of 1/8 to 1/4 inch. The most recent eruptions took place on June 17, August 18, and September 16-17, 1992, with ash plumes reaching up to 30,000 feet, darkening the skies, and dusting Anchorage with ash once again.

The other volcanoes have also been active. Gases are frequently seen venting near the summit of Mount Iliamna, but there are no documented reports of recent eruptions, according to the USGS. Redoubt Volcano, just north of Iliamna, awakened December 14, 1989, dumping varying amounts of ash primarily north and west of the volcano and lightly dusting Anchorage and Kenai. Periodic eruptions continued throughout the week before Christmas, disrupting holiday air traffic. Eruptions continued until April 21, 1990. Until 1989, Redoubt had not erupted since 1966.

Augustine erupted most recently, in 2005/2006. Both this eruption and an earlier one in 1986 sent ash several miles high and disrupted air traffic in south-central Alaska for several days.

All four of these volcanoes are continuously monitored by the Alaska Volcano Observatory in Anchorage.