Griggs
Stratovolcano in United States
Key Facts
Elevation
2,317 m (7,602 ft)
Type
Stratovolcano
Location
58.354°, -155.092°
Region
Alaska Peninsula Volcanic Arc
Rock Type
Andesite / Basaltic Andesite
Tectonic Setting
Subduction zone
Location
Loading map...
Overview
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.
Volcanic Hazards & Risk Assessment
Primary Hazards
- Pyroclastic flows
- Lava flows
- Volcanic bombs and ballistics
- Lahars and mudflows
Risk Level
Geological Composition & Structure
Rock Types
Tectonic Setting
Age & Formation
Eruption Statistics & Analysis
| Metric | Value | Global Ranking | Significance |
|---|---|---|---|
| Total Recorded Eruptions | Unknown | Low | Moderately active volcano |
| Maximum VEI | VEI Unknown | Minor | Local impact potential |
| Recent Activity | 3816 years ago | Historical | Historically active |
Monitoring & Alert Status
Monitoring Networks
Current Status
Nearby Volcanoes in North America Volcanic Regions
Quick Info
- •Smithsonian ID: 312190
- •Evidence: Eruption Dated
- •Epoch: Holocene
About the Photo
Griggs is the highest of a group of volcanoes in the Katmai area, located 10 km behind the volcanic arc. Active fumaroles are within the summit crater and along the upper SW flank. Tephra from the 1912 Novarupta eruption cover the flanks in this 1990 view from the SW.
Photo by Game McGimsey, 1990 (Alaska Volcano Observatory, U.S. Geological Survey).
Authority Sources
Related Volcanoes
Basic Information
This page shows basic data from the Smithsonian Global Volcanism Program. For more detailed information, visit the official Smithsonian page.