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Ruby

Stratovolcano in United States

Last Eruption: 2023

Key Facts

Elevation

-174 m (-571 ft)

Type

Stratovolcano

Location

15.605°, 145.572°

Region

Mariana Volcanic Arc

Total Eruptions

3

Max VEI

VEI 1

Rock Type

Basalt / Picro-Basalt

Tectonic Setting

Subduction zone

Location

Loading map...

Eruption Timeline

2023 CENotable

Most recent confirmed eruption

2020 CEVEI 3

Historical eruption (estimated)

2013 CEVEI 1

Historical eruption (estimated)

Overview

Ruby is a basaltic submarine volcano that rises to within about 200 m of the ocean surface near the southern end of the Mariana arc NW of Saipan. An eruption was detected in 1966 by sonar signals (Norris and Johnson, 1969). Submarine explosions were heard in 1995, accompanied by a fish kill, sulfurous odors, bubbling water, and the detection of volcanic tremor.

Volcanic Hazards & Risk Assessment

Primary Hazards

  • Pyroclastic flows
  • Lava flows
  • Volcanic bombs and ballistics
  • Lahars and mudflows

Risk Level

Population at RiskModerate
Infrastructure RiskHigh
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
Eruption Observed

Eruption Statistics & Analysis

MetricValueGlobal RankingSignificance
Total Recorded Eruptions3LowModerately active volcano
Maximum VEIVEI 1MinorLocal impact potential
Recent Activity3 years agoVery RecentCurrently active

Monitoring & Alert Status

Monitoring Networks

Global Volcanism Program
International eruption database

Current Status

Active
Recent volcanic activity detected. Continuous monitoring in place.

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: 284202
  • Evidence: Eruption Observed
  • Epoch: Holocene

About the Photo

Ruby submarine volcano in the southern Mariana arc is seen in this bathymetric data looking from the NW with 2x vertical exaggeration. Depths in this image range from 184 to 2,955 m, and it rises to within 230 m of the ocean surface NW of Saipan. There was an eruption detected in 1966 by sonar signals. In 1995 submarine explosions were heard, accompanied by a fish kill, sulfurous odors, bubbling water, and the detection of volcanic tremor.

Image courtesy of Susan Merle (Oregon State University/NOAA Vents Program).

Basic Information

This page shows basic data from the Smithsonian Global Volcanism Program. For more detailed information, visit the official Smithsonian page.