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Cerro Azul

Home of the 20th Century's Forgotten Giant Eruption

Elevation

3,788 m

Last Eruption

1967

Type

Stratovolcano

Country

Chile

Location

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Volcanic Hazards & Risk Assessment

Primary Hazards

  • 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 Activity59 years agoHistoricalRecently active

Monitoring & Alert Status

Monitoring Networks

Global Volcanism Program
International eruption database

Current Status

Normal
No recent activity. Routine monitoring continues.

Authority Sources

Smithsonian GVP
Official volcano database

Related Volcanoes

All Chile Volcanoes
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Stratovolcano Volcanoes
By volcano type
Maule Region
Regional volcanoes

Other Volcanoes in Chile

Interesting Facts

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The 1932 Quizapu eruption ejected an estimated 9.5 km3 of dacitic tephra — nearly eight times the volume of the 1980 Mount St. Helens eruption.

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Ash from the 1932 eruption was deposited as far as Buenos Aires, Argentina, approximately 1,500 km to the east.

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The Quizapu crater, formed during the 1932 eruption, measures 600-700 m wide and 150 m deep.

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All 11 recorded eruptions at Cerro Azul have originated from the Quizapu flank vent, not from the summit crater.

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The 1932 eruption is one of the largest and least known major volcanic events of the 20th century — a 'forgotten giant' of modern volcanism.

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The first eruption at Quizapu in 1846 was predominantly effusive, producing dacitic lava flows — a stark contrast to the cataclysmic explosion that followed 86 years later.

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The eruption column in April 1932 reached an estimated 27-30 km altitude, penetrating deep into the stratosphere.

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Cerro Azul means 'Blue Hill' in Spanish — one of the most common mountain names in Latin America.

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The volcano's dacitic magma composition is similar to that of Mount Pinatubo and Mount St. Helens, explaining its capacity for large explosive eruptions.

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The volcano has been quiescent since 1967, a repose period of approximately 58 years.

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Cerro Azul is part of the Descabezado Grande-Cerro Azul system, with Descabezado Grande (3,953 m) to the north.

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The remote location of the 1932 eruption meant minimal casualties despite the eruption's enormous magnitude.

Frequently Asked Questions

What was the 1932 Quizapu eruption?
The April 1932 eruption from the Quizapu vent on Cerro Azul's northern flank was one of the largest volcanic eruptions of the 20th century, rated VEI 5. It ejected an estimated 9.5 km3 of dacitic tephra — nearly eight times the volume of the 1980 Mount St. Helens eruption. The eruption column reached 27-30 km altitude, and ash was deposited as far as Buenos Aires, 1,500 km away. The explosion created the Quizapu crater (600-700 m wide, 150 m deep). Despite its magnitude, casualties were minimal due to the volcano's remote location.
Is Cerro Azul still active?
Yes, Cerro Azul is classified as an active stratovolcano. Its most recent eruption occurred in August 1967, a small explosive event (VEI 2) from the Quizapu vent. The 58-year repose since then is within normal ranges for Andean stratovolcanoes. The volcano's demonstrated capacity for VEI 5 eruptions, as shown by the catastrophic 1932 event, means it remains a significant long-term hazard. It is monitored by Chile's SERNAGEOMIN.
How big was the 1932 eruption compared to other eruptions?
The 1932 Quizapu eruption (VEI 5, 9.5 km3 tephra) was one of the four or five largest eruptions of the 20th century. It was comparable in volume to the 1902 Santa Maria eruption (8.5-10 km3) and the 1991 Pinatubo eruption (~10 km3), both rated VEI 6. It was significantly larger than the 1980 Mount St. Helens eruption (1.2 km3). Only the 1912 Novarupta eruption (13 km3) clearly exceeded it in the 20th century.
Where is Cerro Azul volcano?
Cerro Azul is located in the Maule Region of central Chile, in the southern Andes near the Argentine border, at approximately 35.65 S, 70.76 W. It is a remote, sparsely populated area with limited road access. The volcano is the southern component of the Descabezado Grande-Cerro Azul volcanic system within the Southern Andean Volcanic Arc.
What is Quizapu?
Quizapu is a major volcanic vent (crater) on the northern flank of Cerro Azul. It formed during the volcano's first recorded eruption in 1846 and has been the source of all 11 subsequent eruptions. The Quizapu crater in its current form — 600-700 m wide and 150 m deep — was created by the massive VEI 5 eruption of April 1932. The name is believed to derive from the Mapuche language.
Could the 1932 eruption happen again?
Yes, a future eruption of similar or greater magnitude is possible at Cerro Azul, though the timing is unpredictable. The volcano's dacitic magma composition is inherently capable of producing large explosive eruptions, as demonstrated in 1932. A repeat event would deposit ash across central Chile and Argentina, disrupting aviation, agriculture, and daily life over a wide area. The volcano's remote location provides a natural buffer against direct casualties, but the far-reaching ashfall would be the primary concern.