Photo of this volcano
  • United States
  • Alaska
  • Caldera
  • 1931 CE
  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 56.88°N
  • 158.17°W

  • 1341 m
    4398 ft

  • 312090
  • Latitude
  • Longitude

  • Summit

  • Volcano

The Global Volcanism Program has no activity reports for Aniakchak.

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

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

Eruptive History

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

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
[ 1951 Jun 25 ] [ 1951 Jun 25 ] Discredited    
[ 1942 ] [ Unknown ] Uncertain    
1931 May 1 1931 Jun 13 (in or after) Confirmed 4 Historical Observations West and SW caldera floor
1540 ± 100 years Unknown Confirmed 4 Radiocarbon (corrected) NW & S caldera floor (Half Cone, Vent Mtn)
1470 ± 20 years Unknown Confirmed   Radiocarbon (corrected) SE caldera floor (New Cone)
1370 ± 55 years Unknown Confirmed   Radiocarbon (corrected) NW caldera floor (Half Cone)
1280 ± 145 years Unknown Confirmed   Radiocarbon (corrected) NW caldera floor (Half Cone)
1190 ± 30 years Unknown Confirmed   Radiocarbon (corrected) NW caldera floor (Half Cone)
1120 ± 80 years Unknown Confirmed   Radiocarbon (corrected) East-central caldera (Surprise Cone)
1050 (?) Unknown Confirmed   Tephrochronology Vent Mtn and other vents?
0700 ± 250 years Unknown Confirmed 0 Tephrochronology S & NW caldera floor (Vent Mtn & Half Cone)
0460 (?) Unknown Confirmed   Radiocarbon (uncorrected)
0200 ± 255 years Unknown Confirmed   Tephrochronology Northern & western caldera floor
0370 BCE ± 210 years Unknown Confirmed   Radiocarbon (corrected)
1645 BCE ± 10 years Unknown Confirmed 6 Ice Core
2550 BCE ± 500 years Unknown Confirmed   Tephrochronology
5930 BCE ± 240 years Unknown Confirmed   Radiocarbon (corrected) Black Nose Pumice
6300 BCE ± 1250 years Unknown Confirmed 6 Tephrochronology

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.

Photo Gallery

Calderas are very large depressions that form by collapse. Many, like this 10-km-wide caldera that truncates Alaska's Aniakchak volcano, are created by very powerful explosive eruptions that empty a magma chamber beneath a volcano, causing it to collapse inward. Other calderas, such as those on Hawaiian volcanoes, are produced by collapse following major lava extrusion. Calderas often form incrementally, during widely spaced eruptions. Later activity can cover their floors with a wide variety of volcanic landforms.

Photo by M. Woodbridge Williams (National Park Service).
See title for photo information.
U.S. Geological Survey volcanologists on the rim of Vent Mountain, an intracaldera stratocone, look NW towards Half Cone, a prominent feature on the caldera floor and the source of the most-explosive post-caldera eruptions at Aniakchak. The aptly named Half Cone, whose SE side is missing, last erupted about 500 years ago. The NW caldera rim of Aniakchak caldera forms the skyline.

Photo by Christina Neal, 1992 (Alaska Volcano Observatory, U.S. Geological Survey).
See title for photo information.
This view looks south across the caldera from the north rim of Aniakchak. Surprise Lake and its outlet are visible at the upper left. The prominent dark peak on the skyline is Black Nose, a high-standing remnant of pre-caldera volcaniclastics. Hummocky ground in the distance against the caldera wall is a pumice-covered glacier and associated moraine. Surprise Lake once covered a much larger part of the caldera floor before catastrophically draining through a notch in the east caldera rim.

Photo by Tom Miller, 1985 (Alaska Volcano Observatory, U.S. Geological Survey).
See title for photo information.
The Gates is a v-shaped notch in the 1-km-high eastern rim of Aniakchak caldera. Surprise Lake, now restricted to the NW part of the caldera floor, was once much larger. It is thought to have drained catastrophically through The Gates at the time of an eruption at Half Cone about 500 years ago.

Photo by Christina Neal, 1994 (Alaska Volcano Observatory, U.S. Geological Survey).
See title for photo information.
A geologist examines pyroclastic deposits (above hand) from a violent eruption of Half Cone less than 500 years ago. The Half Cone layers overlie dark gray phreatomagmatic deposits from Surprise tuff cone in Aniakchak caldera. The Half Cone eruption produced about 1 cu km of tephra, and resulted in truncation of the SE side of the cone.

Photo by Game McGimsey (Alaska Volcano Observatory, U.S. Geological Survey).
See title for photo information.
The primary 1931 eruption site is nestled against the NW wall of Aniakchak caldera. This crater, about 600 m across, was the site of intermittent explosions of pumice-lithic tephra over the course of several weeks in May and June, 1931. During the final phases of the eruption, a small lava flow and spatter field formed in the bottom of the crater. The 1931 eruption occurred along a fissure cutting through Vent Mountain and across the caldera floor to the west caldera wall.

Photo by Game McGimsey, 1992 (Alaska Volcano Observatory, U.S. Geological Survey).
See title for photo information.

Smithsonian Sample Collections Database

The following 54 samples associated with this volcano can be found in the Smithsonian's NMNH Department of Mineral Sciences collections. Catalog number links will open a window with more information.

Catalog Number Sample Description
NMNH 117233-106 Pumice
NMNH 117233-107 Pumice
NMNH 117233-108 Pumice
NMNH 117233-109 Pumice
NMNH 117233-110 Pumice
NMNH 117233-111 Pumice
NMNH 117233-112 Pumice
NMNH 117233-113 Pumice
NMNH 117233-114 Pumice
NMNH 117233-115 Pumice
NMNH 117233-116 Pumice
NMNH 117233-117 Pumice
NMNH 117233-118 Pumice
NMNH 117233-119 Basalt
NMNH 117233-120 Pumice
NMNH 117233-121 Pumice
NMNH 117233-122 Tuff
NMNH 117233-123 Pumice
NMNH 117233-124 Pumice
NMNH 117233-125 Pumice
NMNH 117233-126 Pumice
NMNH 117233-127 Basalt
NMNH 117233-128 Dacite
NMNH 117233-131 Obsidian
NMNH 117233-132 Pumice
NMNH 117233-133 Pumice
NMNH 117233-134 Pumice
NMNH 117233-135 Pumice
NMNH 117233-136 Pumice
NMNH 117233-137 Pumice
NMNH 117233-138 Pumice
NMNH 117233-139 Andesite
NMNH 117233-140 Basalt
NMNH 117233-141 Basalt
NMNH 117233-143 Basalt
NMNH 117233-144 Basalt
NMNH 117233-145 Pumice
NMNH 117233-146 Pumice
NMNH 117233-147 Pumice
NMNH 117233-148 Pumice
NMNH 117233-149 Pumice
NMNH 117233-150 Pumice
NMNH 117233-151 Pumice
NMNH 117233-152 Pumice
NMNH 117233-153 Pumice
NMNH 117233-154 Pumice
NMNH 117233-155 Pumice
NMNH 117233-156 Pumice
NMNH 117233-157 Pumice
NMNH 117233-158 Basalt
NMNH 117233-159 Pumice
NMNH 117233-160 Pumice
NMNH 117233-193 Basalt
NMNH 117457-1 Obsidian

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