San Jose

Stratovolcano(es) in Chile-Argentina

Last Eruption: 1960

Key Facts

Elevation

6,070 m (19,915 ft)

Type

Stratovolcano(es)

Location

-33.789°, -69.895°

Region

Southern Andean Volcanic Arc

Rock Type

Andesite / Basaltic Andesite

Tectonic Setting

Subduction zone

Location

Loading map...

Overview

Volcán San José lies along the Chile-Argentina border at the southern end of a volcano group that includes the Pleistocene volcanoes of Marmolejo and Espíritu Santo. The glaciated 6070-m-high Marmolejo stratovolcano is truncated by a 4-km-wide caldera, breached to the NW, that has been the source of a massive debris avalanche. San José is a 5856-m-high stratovolcano of Pleistocene-Holocene age with a broad 2 km x 0.

5 km summit region containing overlapping and nested craters, pyroclastic cones, and blocky lava flows. Volcán la Engorda and Volcán Plantat, located SW of Marmolejo and NW of San Jose, have also been active during the Holocene. An 8-km-long lava flow traveled to the SW from the 1-km-wide summit crater of Espíritu Santo volcano, which overlaps the southern slope of Marmolejo.

Mild phreatomagmatic eruptions were recorded from San José in the 19th and 20th centuries.

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	66 years ago	Historical	Recently 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: 357020
•Evidence: Eruption Observed
•Epoch: Holocene

About the Photo

Volcán San José on the far left horizon rises to the north above ice pinnacles at the Nieves Negras pass on the Chile/Argentina border. The summit of San José is formed by a cluster of six Holocene craters, pyroclastic cones, and blocky lava flows that lie within a series of elongated, 0.5 x 2 km wide nested craters. Mild phreatomagmatic eruptions were recorded at San José in the 19th and 20th centuries.

Photo courtesy of Oscar González-Ferrán (University of Chile).