Snowy Mountain

Geography & Climate

Snowy Mountain is located in United States, within the Alaska Peninsula Volcanic Arc of the broader North America Volcanic Regions. Situated at 58.34° N, 154.68° W in the Northern Hemisphere, the volcano lies within a subarctic climate zone. At 2,162 meters above sea level, Snowy Mountain rises above the surrounding terrain into montane or subalpine conditions. The elevation creates distinct ecological zones along its flanks, from forested lower slopes to exposed rocky terrain near the summit. The volcanic landform is characterized as a composite, which describes the physical shape and structure of the volcanic edifice as observed from the surface.

Geological Context

Snowy Mountain sits in a subduction zone, where one tectonic plate dives beneath another, creating intense heat and pressure that generates magma. Subduction zones are responsible for many of the world's most explosive volcanoes and deadliest eruptions. For communities in United States near Snowy Mountain, this tectonic setting means the volcano is capable of producing powerful explosive eruptions, pyroclastic flows, and lahars that can threaten populated areas within tens of kilometers of the summit. The dominant rock type is andesite / basaltic andesite, a dark, fine-grained volcanic rock that forms from rapidly cooling, low-viscosity lava. Basaltic eruptions tend to be less explosive and produce fluid lava flows that can travel long distances. While less immediately dangerous than explosive eruptions, basaltic lava flows can destroy structures and infrastructure in their path, and volcanic gases released during these eruptions can affect air quality over a wide area.

Eruption History Summary

Snowy Mountain has 1 recorded eruption in the geological database, spanning from 1710 CE to 1710 CE.

GVP Reference Summary

Snowy Mountain, located 15 km NE of Mount Katmai, is the SW-most of a chain of closely spaced volcanoes extending NE along the crest of the Alaska Range. More than 90% of the volcano is covered by glacial ice, which prompted the naming of the volcano by members of the 1917 Katmai Expedition. Two small andesitic-dacitic stratovolcanoes, SW Snowy and NE Snowy, originated about 200,000 years ago. Collapse of NE Snowy during the Holocene produced a large debris avalanche that traveled to the north and left a large breached crater inside which a blocky lava dome was constructed. Peat beneath an ash layer thought to be associated with the the lava dome was radiocarbon dated at about 250 +/- 70 years ago. No eruptive activity has been observed and documented. Wood and Kienle (1990) noted that an active fumarole field at the summit had melted holes through the ice, and there was a zone of shallow seismicity beneath that mountain that is probably due to the hydrothermal system.

— Smithsonian Institution, Global Volcanism Program