About Griggs
Griggs is a stratovolcano rising to 2,317 meters (7,602 feet) in United States's North America Volcanic Regions. Its last known eruption dates to 1790 BCE, in prehistoric times. The volcano has produced 1 recorded eruption.
Geography & Climate
Griggs is located in United States, within the Alaska Peninsula Volcanic Arc of the broader North America Volcanic Regions. Situated at 58.35° N, 155.09° W in the Northern Hemisphere, the volcano lies within a subarctic climate zone. At 2,317 meters above sea level, Griggs 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
Griggs 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 Griggs, 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
Griggs has 1 recorded eruption in the geological database, spanning from 1790 BCE to 1790 BCE.
GVP Reference Summary
The summit of Mount Griggs towers above Knife Creek on the NE side of the Valley of Ten Thousand Smokes. The volcano is offset west of the NE-trending alignment of volcanoes in the Katmai area. The broad stratovolcano, formerly known as Knife Peak, consists of a late-Pleistocene edifice with glacial valleys on the north that was truncated on its SW side by an early Holocene collapse. A Holocene volcano was subsequently constructed within the 1.5-km-wide scarp left following a large SW-flank debris avalanche. Nested cones with three concentric craters mostly fill the scarp, and thick, blocky lava flows cover the SW flanks below the collapse scarp. In contrast to the more silicic centers of the Katmai area along the crest of the range, lava flows from Griggs are dominantly andesitic in composition, and dacitic lava flows are uncommon. No eruptions have been observed, but noisy fumarolic jets near the summit can be heard from the valley floor.
— Smithsonian Institution, Global Volcanism Program
1 Recorded Eruption
| Year | VEI | Type | Area |
|---|---|---|---|
| 1790 BCE | — | Confirmed Eruption | — |
Real-Time Data
USGS Alert Level
Thermal Anomalies
Frequently Asked Questions About Griggs
Is Griggs an active volcano?+
Griggs is not currently classified as active. Its activity evidence is listed as "Eruption Dated." The last known eruption was in 1790 BCE. However, no volcano is ever considered permanently extinct.
When did Griggs last erupt?+
The most recent recorded eruption of Griggs occurred in 1790 BCE. The eruption was classified as a "Confirmed Eruption." Griggs has 1 recorded eruption in total.
How high is Griggs?+
Griggs has a summit elevation of 2,317 meters (7,602 feet) above sea level. At 2,317 meters, it is comparable in height to many significant mountain peaks and stands well above the tree line.
What type of volcano is Griggs?+
Griggs is classified as a Stratovolcano. Stratovolcanoes (also called composite volcanoes) are steep, conical volcanoes built up by many layers of hardened lava, tephra, and volcanic ash. They are among the most common and dangerous types, known for explosive eruptions.
Where is Griggs located?+
Griggs is located in United States, in the North America Volcanic Regions. More specifically, it lies within the Alaska Peninsula Volcanic Arc. Its exact coordinates are 58.354° latitude, -155.092° longitude.
Is it safe to visit Griggs?+
Griggs can generally be visited, but as with any volcano, visitors should check local conditions and any advisory notices before traveling. United States may have specific regulations for accessing volcanic areas. Guided tours are often the safest and most informative way to experience a volcano.
