Although no historic eruptions have been reported from Mount Griggs, vigorously active fumaroles persist in a summit crater and along the upper southwest flank.

[1] The slopes of Mount Griggs are heavily mantled by fallout from the 1912 eruption of Novarupta volcano.

The volume of the volcanic edifice is estimated at 25 cubic kilometers (6.0 cu mi).

Isotopic analysis indicates that the source of Griggs' magma is distinct from the other Katmai volcanoes.

[4] The mountain was named for Dr. Robert Fiske Griggs (1881–1962), botanist, whose explorations of the area, after the eruption of Mount Katmai in 1912, led to the creation of Katmai National Monument by President Woodrow Wilson in 1918.