🌋VolcanoAtlas

Cerro Hudson

Patagonia's Hidden Explosive Giant

Elevation

1,905 m

Last Eruption

2011

Type

Stratovolcano with ice-filled caldera

Country

Chile

Location

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Volcanic Hazards & Risk Assessment

Primary Hazards

  • Pyroclastic flows and surges
  • Large explosive eruptions (VEI 4+)
  • Ash fall and tephra deposits
  • Lahars and debris flows
  • 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
Unknown
Silica Content
Varied composition

Tectonic Setting

Unknown
Intraplate setting with hotspot or regional volcanic activity.

Age & Formation

Epoch
Unknown
Evidence
Unknown

Eruption Statistics & Analysis

MetricValueGlobal RankingSignificance
Total Recorded EruptionsUnknownLowModerately active volcano
Maximum VEIVEI UnknownMinorLocal impact potential
Recent Activity15 years agoRecentRecently active

Monitoring & Alert Status

Monitoring Networks

Global Volcanism Program
International eruption database

Current Status

Watch
Dormant but monitored. Capable of renewed activity.

Authority Sources

Smithsonian GVP
Official volcano database

Related Volcanoes

All Chile Volcanoes
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Stratovolcano with ice-filled caldera Volcanoes
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Aysén Region
Regional volcanoes

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Interesting Facts

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Cerro Hudson has produced two VEI 6 eruptions during the Holocene (~4750 BCE and ~1890 BCE), each ejecting more than 10 km³ of tephra — volumes comparable to the 1883 Krakatau eruption.

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The volcano's 10-km-wide ice-filled caldera was not recognized as volcanic until the 1971 eruption, making it one of the last major caldera volcanoes discovered in the 20th century.

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The 1991 VEI 5 eruption deposited ash over 100,000 km² of Argentine Patagonia and reached the Falkland Islands more than 1,000 km to the east.

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Over one million sheep and cattle perished from ash ingestion following the 1991 eruption, causing an estimated $50 million in livestock losses.

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The 1991 eruption's sulfur loading combined with Mount Pinatubo's eruption two months earlier contributed to global temperatures dropping approximately 0.5°C in 1992–1993.

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Cerro Hudson is the southernmost subduction-related volcano in the Chilean Andes, sitting near the Chile Triple Junction.

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The 1991 eruption created a new 800-m-wide crater in the southwest portion of the caldera.

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The massive volcanic edifice covers approximately 300 km² — an area larger than the city of Birmingham, UK.

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Despite producing some of the largest eruptions in the southern Andes, Cerro Hudson rises to only 1,905 m — less than half the height of many Andean stratovolcanoes.

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The volcano produces unusually mafic (basaltic) magma for a highly explosive volcano — its explosivity is amplified by magma-ice interaction within the caldera.

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The northwest breach in the caldera channels the Río de Los Huemeles, the primary pathway for lahars during eruptions.

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Cerro Hudson's 1991 eruption was the largest in Chile since Quizapu in 1932.

Frequently Asked Questions

Is Cerro Hudson still active?
Yes, Cerro Hudson is an active volcano that last erupted in October 2011. The volcano has produced 15 recorded eruptions over the past 10,000 years, including two VEI 6 events and the devastating VEI 5 eruption of 1991. SERNAGEOMIN, Chile's geological service, monitors the volcano with seismometers, webcams, and satellite systems. Persistent hydrothermal activity within the ice-filled caldera indicates ongoing magmatic processes. Scientists consider future eruptions likely and regard Cerro Hudson as one of South America's highest-priority volcanic monitoring targets.
What happened during the 1991 Cerro Hudson eruption?
The August 1991 eruption of Cerro Hudson was a VEI 5 event and one of the largest volcanic eruptions of the late 20th century. It proceeded in two phases: a lateral blast on August 8–9 followed by a climactic Plinian eruption on August 12 that sent an ash column 16–18 km high. Winds carried ash eastward across Argentine Patagonia, reaching the Falkland Islands over 1,000 km away. The eruption killed over one million livestock through ash ingestion, caused an estimated $50 million in agricultural losses, and formed a new 800-m-wide crater. Its sulfur emissions, combined with Mount Pinatubo's eruption months earlier, contributed to global cooling.
How big were Cerro Hudson's largest eruptions?
Cerro Hudson produced two VEI 6 eruptions during the Holocene — around 4750 BCE and 1890 BCE — each ejecting more than 10 km³ of tephra. These rank among the largest explosive eruptions in the southern Andes over the past 10,000 years and are comparable in magnitude to the 1883 Krakatau eruption or the 1991 Pinatubo eruption. The 1991 eruption, at VEI 5, ejected approximately 4 km³ of tephra. Having two VEI 6 events in its Holocene record makes Cerro Hudson one of the most explosively productive volcanoes in all of South America.
Where is Cerro Hudson located?
Cerro Hudson is located in the Aysén Region of southern Chile at 45.9°S latitude, making it the southernmost subduction-related volcano in the Chilean Andes. The nearest city is Coyhaique, approximately 140 km to the north. The volcano sits in an extremely remote area of Patagonia, surrounded by temperate rainforest and accessible only by challenging overland routes. Its position near the Chile Triple Junction, where three tectonic plates converge, places it in a geologically complex setting.
Why was Cerro Hudson's caldera not discovered until 1971?
Cerro Hudson's 10-km-wide caldera remained unrecognized because it is completely filled with glacial ice and snow, giving the mountain an unremarkable appearance indistinguishable from surrounding non-volcanic peaks. The remote location in southern Chilean Patagonia, with difficult access and sparse population, meant that the area received limited geological survey attention. It was only when the explosive 1971 eruption produced ashfall and lahars that scientists investigated and identified the summit depression as a volcanic caldera. The discovery prompted a reassessment of volcanic hazards across the entire Aysén Region.
How tall is Cerro Hudson?
Cerro Hudson rises to 1,905 m (6,250 ft) above sea level — surprisingly modest for a volcano capable of such enormous eruptions. Many Andean stratovolcanoes tower above 4,000–6,000 m, but Hudson's relatively low elevation belies its vast footprint (approximately 300 km²) and massive caldera (10 km wide). The low summit height combined with the ice-filled caldera contributed to the volcano remaining unrecognized as volcanic until 1971.
Could Cerro Hudson erupt again like 1991?
Yes, volcanologists consider future large eruptions at Cerro Hudson entirely plausible. The volcano's Holocene record includes two eruptions even larger than the 1991 event — VEI 6 events around 4750 BCE and 1890 BCE. The average recurrence interval between significant eruptions over the past 10,000 years is roughly 700–1,000 years, and it has been only about 30 years since the last major event. A repeat VEI 5 or VEI 6 eruption would have devastating consequences for Patagonia and potentially measurable hemispheric climate effects.
What hazards does Cerro Hudson pose?
Cerro Hudson poses several serious hazards. Ashfall from large eruptions can blanket hundreds of thousands of square kilometers, as the 1991 eruption demonstrated across Argentine Patagonia. Pyroclastic flows from major eruptions could travel tens of kilometers from the caldera. Lahars (volcanic mudflows) are a particular concern because the ice-filled caldera provides abundant meltwater that is channeled through the northwest breach down the Río de Los Huemeles. A VEI 6 eruption could inject enough sulfur aerosols into the stratosphere to produce measurable hemispheric temperature cooling.