Novarupta

Geography & Climate

Novarupta is located in United States, within the Alaska Peninsula Volcanic Arc of the broader North America Volcanic Regions. Situated at 58.27° N, 155.16° W in the Northern Hemisphere, the volcano lies within a subarctic climate zone. With a summit elevation of 841 meters above sea level, Novarupta 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

Novarupta 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 Novarupta, 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 rhyolite, a silica-rich volcanic rock associated with highly viscous magma. Rhyolitic eruptions can be extremely explosive and are responsible for some of the largest volcanic events in Earth's history, including supervolcanic caldera-forming eruptions. The high silica content traps dissolved gases, building enormous pressure that can lead to catastrophic explosive releases.

Eruption History Summary

Novarupta has 1 recorded eruption in the geological database, spanning from 1912 CE to 1912 CE. The most powerful recorded event was a colossal eruption capable of affecting global climate for years in 1912 CE, reaching VEI 6 on the Volcanic Explosivity Index. The most recent eruption in 1912 CE places this volcano within the modern era of volcanological observation.

Significance

Novarupta has produced at least one eruption of VEI 6 or higher, placing it among the most powerful volcanic systems on Earth. Eruptions of this magnitude inject massive quantities of sulfur dioxide into the stratosphere, affecting global climate by lowering average temperatures for one to three years after the event.

GVP Reference Summary

Novarupta, the least topographically prominent volcano in the Katmai area, was formed during a major eruption in 1912. This eruption was the world's largest during the 20th century and produced a voluminous rhyolitic airfall tephra and the renowned Valley of Ten Thousand Smokes (VTTS) ash flow. At the end of the eruption a small, 65-m-high, 400-m-wide lava dome grew within the source vent of the VTTS ashflow, a 2-km-wide area of subsidence NW of Trident volcano. The NE side of the Falling Mountain lava dome of the Trident volcanic cluster, as well as Broken Mountain and Baked Mountain, was removed by collapse of the Novarupta depression, which is marked by radial and scalloped arcuate fractures. Much larger collapse took place at Katmai volcano, 10 km E, where a 3 x 4 km caldera formed in response to magma reservoir drainage toward Novarupta.

— Smithsonian Institution, Global Volcanism Program