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Koniuji

Stratovolcano in United States

Last Eruption: -1150

Key Facts

Elevation

273 m (896 ft)

Type

Stratovolcano

Location

52.220°, -175.130°

Region

Aleutian Ridge Volcanic Arc

Rock Type

Andesite / Basaltic Andesite

Tectonic Setting

Subduction zone

Location

Loading map...

Overview

The very small, 1 x 1. 5 km Koniuji Island, between Atka and Kasatochi volcanoes, is the emergent top of a mostly submarine volcano. Located about 20 km N of the western side of Atka Island, the volcano is deeply dissected, with a steep, arcuate cliff on the west.

New Ar-Ar dating indicates that the island emerged above sea level aout 15,000 years ago, and that several lava flows and domes were erupted during the Holocene. The summit lava dome is younger than about 3,000 years. Reports of historical eruptive activity may be erroneous and are considered to refer to eruptions of the relatively undissected Kasatochi, 25 km W.

Volcanic Hazards & Risk Assessment

Primary Hazards

  • Pyroclastic flows
  • Lava flows
  • Volcanic bombs and ballistics
  • Lahars and mudflows

Risk Level

Population at RiskModerate
Infrastructure RiskModerate
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 Dated

Eruption Statistics & Analysis

MetricValueGlobal RankingSignificance
Total Recorded EruptionsUnknownLowModerately active volcano
Maximum VEIVEI UnknownMinorLocal impact potential
Recent Activity3176 years agoHistoricalHistorically active

Monitoring & Alert Status

Monitoring Networks

Global Volcanism Program
International eruption database

Current Status

Normal
No recent activity. Routine monitoring continues.

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: 311140
  • Evidence: Eruption Dated
  • Epoch: Holocene

About the Photo

A steep, arcuate cliff drops nearly 300 m to the coast on the western side of Koniuji Island. This small, 1 x 1.5 km wide island, located between Atka Island and Kasatochi volcano, is the emergent top of a mostly-submarine volcano. A NE-trending fault is visible on the SE side of the island (right).

Photo by E. Bailey, 1982 (U.S. Fish and Wildlife Service).

Basic Information

This page shows basic data from the Smithsonian Global Volcanism Program. For more detailed information, visit the official Smithsonian page.