Kaguyak

Geography & Climate

Kaguyak is located in United States, within the Alaska Peninsula Volcanic Arc of the broader North America Volcanic Regions. Situated at 58.61° N, 154.02° W in the Northern Hemisphere, the volcano lies within a subarctic climate zone. With a summit elevation of 901 meters above sea level, Kaguyak is a moderately sized peak that remains accessible to hikers and researchers for much of the year. The volcanic landform is characterized as a caldera, which describes the physical shape and structure of the volcanic edifice as observed from the surface.

Geological Context

Kaguyak 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 Kaguyak, 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 dacite, an intermediate to silica-rich volcanic rock. This composition typically produces more viscous magma, leading to more explosive eruptions with ash columns and pyroclastic flows. Andesitic and dacitic magmas build pressure before erupting, which is why volcanoes with this rock chemistry are often associated with Plinian-style eruptions that can send ash tens of kilometers into the atmosphere and disrupt aviation across entire regions.

Eruption History Summary

Kaguyak has 2 recorded eruptions in the geological database, spanning from 4060 BCE to 3850 BCE. The most powerful recorded event was a paroxysmal eruption with devastating regional consequences in 3850 BCE, reaching VEI 5 on the Volcanic Explosivity Index. These eruptions span roughly 210 years of volcanic history.

Significance

With a maximum recorded VEI of 5, Kaguyak has demonstrated the capacity for paroxysmal eruptions comparable to the 1980 eruption of Mount St. Helens. Eruptions of this scale can devastate areas within 20-30 kilometers and produce ash fall that disrupts aviation and agriculture across hundreds of kilometers.

GVP Reference Summary

The 2.5-km-wide Kaguyak caldera in the NE part of Katmai National Park is filled by a lake more than 180 m deep whose surface lies 550 m below the caldera rim. The volcano rises directly from lowland areas near sea level south of the Big River. Initially considered to be a typical stratovolcano truncated by a caldera, the pre-caldera edifice has been shown to consist of nine contiguous late-Pleistocene lava dome clusters, most of which lie east of the present caldera. A large post-caldera lava dome extends into the lake on the SW side and another dome forms a small island in the center of the lake. The caldera is unglaciated, and distal tephras from the caldera-forming eruption have been radiocarbon dated at about 5,800 years before present. Voluminous dacitic pyroclastic-flow deposits surround the caldera and reached Shelikof Strait to the SE.

— Smithsonian Institution, Global Volcanism Program