Atacazo

Photo of this volcano
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  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 0.353°S
  • 78.617°W

  • 4463 m
    14639 ft

  • 352021
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number

The Global Volcanism Program has no activity reports for Atacazo.

The Global Volcanism Program has no Weekly Reports available for Atacazo.

The Global Volcanism Program has no Bulletin Reports available for Atacazo.

Atacazo stratovolcano, located about 25 km SW of the capital city of Quito, consists of a large Pleistocene andesitic stratovolcanoes truncated by a late-Pleistocene to Holocene caldera. Growth of La Carcacha stratovolcano was followed by construction of Atacazo, a stratovolcano with flank lava domes. The 6-km-wide caldera, which is breached to the SW, is partially filled by three dacitic lava-dome complexes of Holocene age. Two andesitic lava domes are also found on the SE flank. Several plinian eruptions have occurred at the Atacazo-Ninahuilca complex during the Holocene, accompanied by growth of lava domes. The latest dated eruption took place about 2300 years ago, forming the Ninahuilca Chico lava domes within the summit caldera. Dome formation was accompanied by plinian explosive eruptions and pyroclastic flows that traveled 35 km down valleys to the west.

Summary of Holocene eruption dates and Volcanic Explosivity Indices (VEI).

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
0320 BCE ± 16 years Unknown Confirmed 5 Radiocarbon (uncorrected) Ninahuilca Chico II dome, N6 tephra
2490 BCE ± 40 years Unknown Confirmed 5 Radiocarbon (uncorrected) Ninahuilca Chico I dome, N5 tephra
3490 BCE ± 100 years Unknown Confirmed 4 Radiocarbon (uncorrected) Arenal II dome, N4 tephra
6910 BCE (in or before) Unknown Confirmed 4 Radiocarbon (uncorrected) La Cocha II dome, N3 tephra

This compilation of synonyms and subsidiary features may not be comprehensive. Features are organized into four major categories: Cones, Craters, Domes, and Thermal Features. Synonyms of features appear indented below the primary name. In some cases additional feature type, elevation, or location details are provided.



Cones
Feature Name Feature Type Elevation Latitude Longitude
Caracha, La Stratovolcano


Domes
Feature Name Feature Type Elevation Latitude Longitude
Arenal I Dome 0° 22' 0" S 78° 41' 0" W
Arenal II Dome 4280 m
Cocha I, La Dome 3798 m
Cocha II, La Dome 3798 m
Cuscungo Dome
Gallo Cantano Dome
Ninahuilca
    Minasguilca Chico
Dome 3834 m 0° 22' 16" S 78° 38' 20" W
Ninahuilca Chico I Dome
Ninahuilca Chico II Dome
Omoturco Dome 3566 m 0° 24' 0" S 78° 36' 0" W
Viudita, La Dome 3724 m 0° 25' 0" S 78° 37' 0" W
Atacazo stratovolcano, located 20 km south of Quito, is seen here from the west along the road to Guayaquil. The volcano contains a summit caldera that is partially filled by lava domes of Holocene age. Lava domes are also found on the SE flank. The only dated Holocene eruption took place about 2400 years ago, forming the Ninahuilca lava domes, the peaks below the center horizon.

Photo by John Ewert, 1992 (U.S. Geological Survey).
The Ninahuilca lava domes, which form the twin forested peaks below the right-center horizon, were created during an eruption about 2400 years ago. Growth of the lava domes within the summit caldera of Atacazo volcano was accompanied by plinian explosive eruptions and pyroclastic flows that traveled 35 km down valleys to the west.

Photo by John Ewert, 1992 (U.S. Geological Survey).

The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography. Discussion of another volcano or eruption (sometimes far from the one that is the subject of the manuscript) may produce a citation that is not at all apparent from the title.

Barragan R, Geist D, Hall M, Larson P, Kurz M, 1998. Subduction controls on the compositions of lavas from the Ecuadorian Andes. Earth Planet Sci Lett, 154: 153-166.

Hall M L, 1977. El Volcanismo en El Ecuador. Quito: Biblioteca Ecuador, 120 p.

Hidalgo S, Monzier M, ALmeida E, Chazot G, Eissen J-P, van der Plicht J, Hall M L, 2008. Late Pleistocene and Holocene activity of the Atacazo-Ninahuilca volcanic complex (Ecuador). J Volc Geotherm Res, 176: 16-26.

Volcano Types

Stratovolcano
Caldera
Lava dome(s)

Tectonic Setting

Subduction zone
Continental crust (> 25 km)

Rock Types

Major
Andesite / Basaltic Andesite
Dacite

Population

Within 5 km
Within 10 km
Within 30 km
Within 100 km
449
212,988
1,837,303
3,769,593

Affiliated Databases

Large Eruptions of Atacazo Information about large Quaternary eruptions (VEI >= 4) is cataloged in the Large Magnitude Explosive Volcanic Eruptions (LaMEVE) database of the Volcano Global Risk Identification and Analysis Project (VOGRIPA).
WOVOdat WOVOdat is a database of volcanic unrest; instrumentally and visually recorded changes in seismicity, ground deformation, gas emission, and other parameters from their normal baselines. It is sponsored by the World Organization of Volcano Observatories (WOVO) and presently hosted at the Earth Observatory of Singapore.
EarthChem EarthChem develops and maintains databases, software, and services that support the preservation, discovery, access and analysis of geochemical data, and facilitate their integration with the broad array of other available earth science parameters. EarthChem is operated by a joint team of disciplinary scientists, data scientists, data managers and information technology developers who are part of the NSF-funded data facility Integrated Earth Data Applications (IEDA). IEDA is a collaborative effort of EarthChem and the Marine Geoscience Data System (MGDS).
Smithsonian Collections Search the Smithsonian's NMNH Department of Mineral Sciences collections database. Go to the "Search Rocks and Ores" tab and use the Volcano Name drop-down to find samples.