Harunasan

Stratovolcano in Japan

Last Eruption: 550

Key Facts

Elevation

1,449 m (4,754 ft)

Type

Stratovolcano

Location

36.477°, 138.851°

Region

Northeast Japan Volcanic Arc

Rock Type

Andesite / Basaltic Andesite

Tectonic Setting

Subduction zone

Location

Loading map...

Overview

Harunasan volcano is truncated by a small summit caldera containing the symmetrical post-caldera pyroclastic cone of Haruna-Fuji. Harunasan volcano dates back prior to 300,000 years ago and had caldera-producing eruptions at about 200,000 and 40,000 years ago. Viscous lava flows and lava domes were subsequently extruded within and around the caldera, the western side of which is currently partially filled by Lake Haruna.

The Futatsudake lava dome east of the caldera was the source of two large explosive eruptions during the 6th century CE.

Volcanic Hazards & Risk Assessment

Primary Hazards

Pyroclastic flows
Lava flows
Volcanic bombs and ballistics
Lahars and mudflows

Risk Level

Population at RiskHigh

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

Metric	Value	Global Ranking	Significance
Total Recorded Eruptions	Unknown	Low	Moderately active volcano
Maximum VEI	VEI Unknown	Minor	Local impact potential
Recent Activity	1476 years ago	Historical	Historically active

Monitoring & Alert Status

Monitoring Networks

Japan Meteorological Agency (JMA)

Real-time seismic monitoring

Geological Survey of Japan

Geochemical monitoring

Global Volcanism Program

International eruption database

Current Status

Normal

No recent activity. Routine monitoring continues.

Nearby Volcanoes in Northwestern Pacific Volcanic Regions

Regional Volcanic Activity

The Northwestern Pacific 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: 283122
•Evidence: Eruption Dated
•Epoch: Holocene

About the Photo

Harunasan has a small summit caldera containing Haruna-Fuji cone (right). Viscous lava flows and lava domes have formed within and around the caldera. Its western side is currently filled by Lake Haruna, which is visible to the left of the cone. The Futatsudake lava dome, outside the caldera to the E, was the source of two large explosive eruptions during the 6th century CE. This view from the NE also shows a plume emanating from Asamayama on the distant horizon above Lake Haruna.

Photo by Ichio Moriya (Kanazawa University).