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Billy Mitchell

Caldera in Papua New Guinea

Last Eruption: 1580

Key Facts

Elevation

1,544 m (5,066 ft)

Type

Caldera

Location

-6.090°, 155.225°

Region

Bougainville Volcanic Arc

Rock Type

Andesite / Basaltic Andesite

Tectonic Setting

Subduction zone

Location

Loading map...

Overview

Billy Mitchell, a small pyroclastic shield immediately NE of Bagana volcano, has produced some of the largest Holocene eruptions in Papua New Guinea. The andesitic-to-dacitic volcano is truncated by a 2-km-wide caldera containing a shallow lake with a small island near its S shore. Two major explosive eruptions, one about 900 years ago and the other about 370 years ago, produced dacitic pyroclastic-fall deposits that cover most of the northern half of Bougainville Island.

The younger eruption may have been responsible for formation of the nearly vertical, steep-walled summit caldera. Pyroclastic-flow and -surge deposits extend 25 km to the E coast of Bougainville Island.

Volcanic Hazards & Risk Assessment

Primary Hazards

  • Pyroclastic flows and surges
  • Large explosive eruptions (VEI 4+)
  • Ash fall and tephra deposits
  • Lahars and debris flows

Risk Level

Population at RiskModerate
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 Dated

Eruption Statistics & Analysis

MetricValueGlobal RankingSignificance
Total Recorded EruptionsUnknownLowModerately active volcano
Maximum VEIVEI UnknownMinorLocal impact potential
Recent Activity446 years agoHistoricalHistorically active

Monitoring & Alert Status

Monitoring Networks

Global Volcanism Program
International eruption database

Current Status

Normal
No recent activity. Routine monitoring continues.

Nearby Volcanoes in Southwestern Pacific Volcanic Regions

Regional Volcanic Activity
The Southwestern 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: 255011
  • Evidence: Eruption Dated
  • Epoch: Holocene

About the Photo

Billy Mitchell truncated by a 2-km-wide caldera containing a lake. It is seen here from the north, with the eroded, forested Reini volcano on the center horizon and neighboring Bagana volcano at the top right. Billy Mitchell has been the source of some of the largest Holocene eruptions of Papua New Guinea. Two major explosive eruptions, one about 900 years ago and the other about 370 years ago, produced ashfall across most of the N half of Bougainville Island.

Photo by Wally Johnson, 1989 (Australia Bureau of Mineral Resources).

Basic Information

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