Nakanoshima

Stratovolcano(es) in Japan

Last Eruption: 1914

Key Facts

Elevation

979 m (3,212 ft)

Type

Stratovolcano(es)

Location

29.859°, 129.857°

Region

Ryukyu Volcanic Arc

Rock Type

Andesite / Basaltic Andesite

Tectonic Setting

Subduction zone

Location

Loading map...

Overview

The 9 x 5 km island of Nakanoshima is surrounded by coral reefs. A flat plateau separates the older dissected Sakiwaridake volcano on the south from the active andesitic cone of Ontake, which forms the northern half of the island. Ontake contains a summit crater that is filled with water during the rainy season.

Sulfur deposits were mined at a SE-flank solfatara until 1944. Only very minor activity has been reported in historical time. A small mud eruption took place in 1914 at the summit crater, and "smoking" increased in 1949.

Volcanic Hazards & Risk Assessment

Primary Hazards

Risk Level

Population at RiskHigh

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	112 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 Western Pacific Volcanic Regions

Regional Volcanic Activity

The Western 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: 282040
•Evidence: Eruption Observed
•Epoch: Holocene

About the Photo

Nakanoshima island is seen here from a beach on Kuchinoshima to the NNE. The active cone of Ontake to the right has a summit crater that fills with water during the rainy season. The 9 x 5 km island is surrounded by coral reefs, and a flat plateau separates it from an older dissected volcano to the south. Minor activity has been reported in historical time.

Copyrighted photo by Shun Nakano, 2005 (Japanese Quaternary Volcanoes database, RIODB, http://riodb02.ibase.aist.go.jp/strata/VOL_JP/EN/index.htm and Geol Surv Japan, AIST, http://www.gsj.jp/).