Colachi

Stratovolcano in Chile

Key Facts

Elevation

5,631 m (18,474 ft)

Type

Stratovolcano

Location

-23.236°, -67.645°

Region

Central Andean Volcanic Arc

Rock Type

Andesite / Basaltic Andesite

Tectonic Setting

Subduction zone

Location

Loading map...

Overview

Colachi is a andesitic-dacitic stratovolcano that was constructed on an uplifted block of welded ignimbrites. The most recent activity produced pristine silicic lava flows of probable Holocene age, the largest of which covers a 7 km2 area on the saddle between Colachi and the neighboring volcano of Acamarachi (de Silva and Francis, 1991). A smaller flow was erupted on the W flank.

The closely spaced Colachi and Acamarachi volcanoes represent different magmatic systems (Gardeweg 1993, pers. comm. ).

Volcanic Hazards & Risk Assessment

Primary Hazards

Pyroclastic flows
Lava flows
Volcanic bombs and ballistics
Lahars and mudflows

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

Evidence Credible

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

Global Volcanism Program

International eruption database

Current Status

Normal

No recent activity. Routine monitoring continues.

Nearby Volcanoes in South America Volcanic Regions

Regional Volcanic Activity

The South America 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: 355095
•Evidence: Evidence Credible
•Epoch: Holocene

About the Photo

Colachi (left) is an andesitic-dacitic stratovolcano whose most recent activity produced pristine silicic lava flows of probable Holocene age. The largest of these covers a 7 km2 area on the saddle between Colachi and the neighboring volcano of Acamarachi (center horizon). This aerial view from the west also shows the conical peak of Aguas Calientes (far right), a twin volcano of Lascar volcano, whose slopes appear at the lower right. The Talabre valley in the center foreground is partially filled by an andesitic lava flow from Lascar.

Photo by Insitituto Geográfico Militar, courtesy of Oscar González-Ferrán (University of Chile).