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Kasatochi

Stratovolcano in United States

Last Eruption: 2008

Key Facts

Elevation

314 m (1,030 ft)

Type

Stratovolcano

Location

52.177°, -175.508°

Region

Aleutian Ridge Volcanic Arc

Rock Type

Basalt / Picro-Basalt

Tectonic Setting

Subduction zone

Location

Loading map...

Overview

Located at the northern end of a shallow submarine ridge trending perpendicular to the Aleutian arc, Kasatochi is small 2. 7 x 3. 3 km island volcano with a 750-m-wide summit crater lake.

The summit reaches only about 300 m elevation, and the lake surface lies less than about 60 m above the sea. A lava dome is located on the NW flank at about 150 m elevation. The asymmetrical island is steeper on the northern side than the southern, and the crater lies north of the center of the island.

Reports of activity from the heavily eroded Koniuji volcano to the east probably refer to eruptions from Kasatochi. A lava flow may have been emplaced during the first recorded eruption in 1760. A major explosive eruption in 2008 produced pyroclastic flows and surges that swept into the sea, extending the island's shoreline.

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
Basalt / Picro-Basalt
Silica Content
Low (45-52% 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

MetricValueGlobal RankingSignificance
Total Recorded EruptionsUnknownLowModerately active volcano
Maximum VEIVEI UnknownMinorLocal impact potential
Recent Activity18 years agoRecentRecently 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: 311130
  • Evidence: Eruption Observed
  • Epoch: Holocene

About the Photo

A 750-m-wide crater filled with a lake truncates the summit of Kasatochi. Crater walls rise to a maximum height of 314 m above the lake surface, which is less than 60 m above sea level in this 1961 photo. The volcano is located at the northern end of a shallow submarine ridge trending perpendicular to the Aleutian arc and occupies an island volcano 2.7 x 3.3 km wide.

Photo by Dan Rogers, 1961 (courtesy of Alaska Volcano Observatory, U.S. Geological Survey).

Basic Information

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