Sofugan

Stratovolcano in Japan

Key Facts

Elevation

99 m (325 ft)

Type

Stratovolcano

Location

29.794°, 140.342°

Region

Izu Volcanic Arc

Rock Type

Basalt / Picro-Basalt

Tectonic Setting

Subduction zone

Location

Loading map...

Overview

Sofugan is a steep-sided pinnacle that rises 99 m above the sea surface south of Torishima volcano. Its dramatic and isolated setting prompted it to also be known as "Lot's Wife Rocks. " The basaltic-to-andesitic pinnacle is the remnant of a large stratovolcano that is 28 km wide at its base and rises 2200 m above the sea floor.

A submarine depression lies between the pinnacle and an arcuate submarine ridge to the SW that rises to less than 150 m of the sea surface. In 1975 discolored sea water was observed about 500 m north of Sofugan, and the volcano was reclassified as active by the Japan Meteorological Agency in 2003.

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

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

Evidence Uncertain

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	Unknown	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: 284091
•Evidence: Evidence Uncertain
•Epoch: Holocene

About the Photo

The Sofugan pinnacle seen here from the W rises about 100 m above the ocean surface south of Torishima volcano. It is the remnant of a large volcano that is 28 km wide at its base and rose 2,200 m above the sea floor. In 1975 discolored sea water was observed about 500 m N.

Copyrighted photo by Makoto Yuasa, 1985 (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/).