Yokoatejima

Stratovolcano(es) in Japan

Last Eruption: 1835

Key Facts

Elevation

495 m (1,624 ft)

Type

Stratovolcano(es)

Location

28.797°, 128.997°

Region

Ryukyu Volcanic Arc

Rock Type

Andesite / Basaltic Andesite

Tectonic Setting

Subduction zone

Location

Loading map...

Overview

Yokoatejima is a small, 3. 5-km-long, dumbbell-shaped island NW of Amami Oshima Island at the SW end of the Tokara island chain. Two peaks, Higashimine on the east and Nishimine on the west, form the andesitic island.

Higashimine, the high point of the island, has a steep-walled, well-preserved summit crater. An arcuate ridge east of Yokoate-jima appears to be part of 7 x 10 km submarine caldera, with Yokoatejima and Kaminonejima to the NNE being post-caldera cones (Nakano et al. , 2001-).

Yokoatesho (Yokoate Reef) and Kaminone Kaikyu (Kaminone Knoll) lie to NNW and NE of Yokoatejima, respectively. Historical documents at the end of the Edo Period mention ash plumes from Yokoatejima.

Volcanic Hazards & Risk Assessment

Primary Hazards

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 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	191 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: 282021
•Evidence: Eruption Observed
•Epoch: Holocene

About the Photo

Nishimine, the western peak of Yokoatejima, is seen from the NW with a road visible at the left that reaches the summit crater. Yokoatejima is a small, 3.5-km-long island at the SW end of the Tokara island chain with two peaks, Higashimine to the E and Nishimine to the W. It is a post-caldera cone within a 7 x 10 km submarine caldera. Historical documents at the end of the Edo Period mention ash plumes.

Copyrighted photo by Shun Nakano, 2004 (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/).