Marchena

Shield in Ecuador

Last Eruption: 1991

Key Facts

Elevation

343 m (1,125 ft)

Type

Shield

Location

0.330°, -90.470°

Region

Northern Galapagos Volcanic Province

Rock Type

Basalt / Picro-Basalt

Tectonic Setting

Rift zone

Location

Loading map...

Overview

The low shield volcano forming Marchena Island contains one of the largest calderas of the Galápagos Islands. The 6 x 7 km caldera and its outer flanks have been largely buried by a cluster of pyroclastic cones and associated lava flows. Its first historical eruption occurred in 1991.

Other young lava flows, some of which may be only a few thousand, or even a few hundred years old, filled the caldera and flowed down its outer forested flanks, in some cases to the sea.

Volcanic Hazards & Risk Assessment

Primary Hazards

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

Rift zone

Continental rift or intraplate setting with varied eruptive styles.

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	35 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 Eastern Pacific Volcanic Regions

Regional Volcanic Activity

The Eastern 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: 353080
•Evidence: Eruption Observed
•Epoch: Holocene

About the Photo

A large tuff cone rises near Punta Calle on the southern coast of Marchena Island beyond fresh-looking lava flows west of the cone in the foreground. The low shield volcano forming Marchena Island contains one of the largest calderas of the Galápagos Islands. In contrast to other Galápagos volcanoes, the 6 x 7 km caldera and its outer flanks have been largely buried by a cluster of pyroclastic cones and associated lava flows. The first historical eruption of Marchena occurred in 1991.

Photo by Ed Vicenzi, 1984 (Smithsonian Institution).