Fourpeaked

Stratovolcano in United States

Last Eruption: 2006

Key Facts

Elevation

2,105 m (6,906 ft)

Type

Stratovolcano

Location

58.770°, -153.672°

Region

Alaska Peninsula Volcanic Arc

Rock Type

Andesite / Basaltic Andesite

Tectonic Setting

Subduction zone

Location

Loading map...

Overview

Poorly known Fourpeaked volcano in NE Katmai National Park consists of isolated outcrops surrounded by the Fourpeaked Glacier, which descends eastward almost to the Shelikof Strait. The orientation of andesitic lava flows and extensive hydrothermal alteration of rocks near the present summit suggest that it probably marks the vent area. Eruptive activity during the Holocene had not been confirmed prior to the first historical eruption in September 2006.

A N-trending fissure extending 1 km from the summit produced minor ashfall.

Volcanic Hazards & Risk Assessment

Primary Hazards

Pyroclastic flows
Lava flows
Volcanic bombs and ballistics
Lahars and mudflows

Risk Level

Population at RiskModerate

Infrastructure RiskHigh

Aviation RiskSignificant

Geological Composition & Structure

Rock Types

Primary

Andesite / Basaltic Andesite

Silica Content

Intermediate (57-63% SiO₂)

Tectonic Setting

Subduction zone

Formed by oceanic plate subduction, typically producing explosive eruptions due to water-rich magmas.

Age & Formation

Epoch

Holocene

Evidence

Eruption Observed

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	20 years ago	Recent	Recently active

Monitoring & Alert Status

Monitoring Networks

Global Volcanism Program

International eruption database

Current Status

Watch

Dormant but monitored. Capable of renewed activity.

Nearby Volcanoes in North America Volcanic Regions

Regional Volcanic Activity

The North America Volcanic Regions contains multiple active volcanic systems. Cross-regional magma interactions and tectonic stresses can influence eruption patterns across the entire arc. Monitor regional seismic activity and volcanic alerts.

Quick Info

•Smithsonian ID: 312260
•Evidence: Eruption Observed
•Epoch: Holocene

About the Photo

Glaciated Fourpeaked volcano in NE Katmai National Park is seen here from the south with the Swikshak River in the foreground. Holocene eruptions at Fourpeaked had not been confirmed prior to its first recorded eruption in September 2006.

Photo by Jennifer Adleman, 2006 (U S Geological Survey, Alaska Volcano Observatory).