West Mata

Fissure vent(s) in Tonga

Last Eruption: 2009

Key Facts

Elevation

-1,174 m (-3,852 ft)

Type

Fissure vent(s)

Location

-15.100°, -173.750°

Region

Northeast Lau Basin Volcano Group

Rock Type

Andesite / Basaltic Andesite

Tectonic Setting

Subduction zone

Location

Loading map...

Overview

West Mata, a submarine volcano rising to within 1,174 m of the ocean surface, is located in the northeastern Lau Basin at the northern end of the Tofua arc, about 200 km SW of Samoa and north of the Curacoa submarine volcano. Discovered during a November 2008 NOAA Vents Program expedition it was found to be producing submarine hydrothermal plumes consistent with recent lava effusion. A return visit in May 2009 documented explosive and effusive activity from two closely spaced vents, one at the summit, and the other on the SW rift zone.

Volcanic Hazards & Risk Assessment

Primary Hazards

Risk Level

Population at RiskModerate

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	17 years ago	Recent	Recently active

Monitoring & Alert Status

Monitoring Networks

Global Volcanism Program

International eruption database

Current Status

Watch

Dormant but monitored. Capable of renewed activity.

Nearby Volcanoes in Tonga-Kermadec Volcanic Regions

Regional Volcanic Activity

The Tonga-Kermadec 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: 243130
•Evidence: Eruption Observed
•Epoch: Holocene

About the Photo

Incandescence and a plume at the Hades vent of West Mata in May 2009, a submarine volcano with a summit more than 1,000 m below the ocean surface. The volcano is located in the northeastern Lau Basin at the northern end of the Tonga arc, about 200 km SW of Samoa. It was discovered during a November 2008 NOAA Vents Program expedition, when West Mata was observed producing submarine hydrothermal plumes consistent with recent or ongoing lava effusion. A return visit in May 2009 documented explosive and effusive activity.

Courtesy of NSF and NOAA Ocean Exploration Program, 2009.