Niijima

Lava dome(s) in Japan

Last Eruption: 886

Key Facts

Elevation

432 m (1,417 ft)

Type

Lava dome(s)

Location

34.397°, 139.270°

Region

Izu Volcanic Arc

Rock Type

Rhyolite

Tectonic Setting

Subduction zone

Location

Loading map...

Overview

The elongated island of Niijima, SSW of Oshima, is 11 km long and only 2. 5 km wide. Eight low rhyolitic lava domes are clustered in two groups at the northern and southern ends of the island, separated by an area of flat-topped domes and a low isthmus of pyroclastic deposits.

The Mukaiyama complex on the south and the Atchiyama lava dome on the north were formed during eruptions in the 9th century CE, the last known activity. Shikineyama and Zinaito domes form small islands immediately to the SW and W, respectively, during earlier stages of volcanism. Earthquake swarms occurred during the 20th century.

Volcanic Hazards & Risk Assessment

Primary Hazards

Risk Level

Population at RiskHigh

Infrastructure RiskModerate

Aviation RiskSignificant

Geological Composition & Structure

Rock Types

Primary

Rhyolite

Silica Content

High (>68% 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	1140 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: 284020
•Evidence: Eruption Observed
•Epoch: Holocene

About the Photo

Stratified phreatomagmatic deposits are exposed along a cliff on the eastern coast of Niijima, with the flat-topped Miyazukayama lava dome in the background. The 11-km-long island is comprised of eight rhyolite lava domes clustered in two groups. The Mukaiyama complex at the southern end of the island and Achiyama lava dome at the northern end formed during the 9th century CE.

Photo by Ichio Moriya (Kanazawa University).