Hell's Half Acre

Photo of this volcano
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  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 43.5°N
  • 112.45°W

  • 1631 m
    5350 ft

  • 324040
  • Latitude
  • Longitude

  • Summit

  • Volcano

The Global Volcanism Program has no activity reports for Hell's Half Acre.

The Global Volcanism Program has no Weekly Reports available for Hell's Half Acre.

The Global Volcanism Program has no Bulletin Reports available for Hell's Half Acre.

Geological Background

Hell's Half Acre lava field, the easternmost of the young basaltic lava fields of the Snake River Plain, covers an area of about 400 sq km SW of Idaho Falls and is the 2nd largest of the Snake River Plain. Basaltic lavas forming the broad, low shield volcano are dominantly pahoehoe flows that were erupted from a 3-km-long, NW-SE trending vent system at the NW part of the field during a brief eruptive episode about 5200 years ago. The summit vent area contains an irregular, elongate 0.8 x 0.3 km wide central depression that was the site of a former lava lake that fed late-stage flows. About 10 circular pit craters truncate the surface of the lava lake, and two prominent lava tube systems are located near the summit vent complex. Two major lava flow lobes, each about 5 km wide and 10 km long, extend to the south and SW along the flood plain of the Snake River and surround Morgans Pasture, a large kipuka. Interstate 15 highway crosses the SE margin of the lava field SW of the city of Idaho Falls.

Eruptive History

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

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
3250 BCE ± 150 years Unknown Confirmed 0 Radiocarbon (uncorrected)

The Global Volcanism Program has no synonyms or subfeatures listed for Hell's Half Acre.

Photo Gallery

A broad frozen lava lake rises almost to the rim of the 800 x 300 m wide summit crater of Hell's Half Acre shield volcano, the easternmost of the young basaltic lava fields of the Snake River Plain. The 300 x 800 m wide lava lake is seen from the summit of the low shield volcano, with East Butte and Middle Butte visible to the west on the upper right horizon. Dominantly pahoehoe lava flows were erupted from a 3-km-long, NW-SE trending vent system in the NW part of Hells Half Acre lava field about 5200 years ago.

Photo by Lee Siebert, 2002 (Smithsonian Institution).


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.

Greeley R, King J S (eds), 1977. Volcanism of the eastern Snake River Plain, Idaho: a comparative planetary geology guidebook. NASA (Washington, DC), CR-154621: 1-308.

Hughes S S, Smith R P, Hackett W R, Anderson S R, 1999. Mafic volcanism and environmental geology of the eastern Snake River Plain. In: Hughes S S, Thackray G D (eds), {Guidebook to the Geology of eastern Idaho}, Pocatello, Idaho: Idaho Musuem of Nat Hist, p 143-168.

Hughes S S, Smith R P, Hackett W R, McCurry M, Anderson S R, Ferdock G C, 1997. Bimodal magmatism, basaltic volcanic styles, tectonics, and geomorphic processes of the eastern Snake River Plain, Idaho. Brigham Young Univ Geol Studies, 42: 423-458.

IAVCEI, 1973-80. Post-Miocene Volcanoes of the World. IAVCEI Data Sheets, Rome: Internatl Assoc Volc Chemistry Earth's Interior..

Karlo J F, Clemency C V, 1980. Picrite xenoliths from the eastern Snake River Plain, Idaho. Contr Mineral Petr, 73: 173-178.

Kuntz M A, Covington H R, Schorr L J, 1992. An overview of basaltic volcanism of the eastern Snake River Plain. In: Link P K, Kuntz M A, Platt L B (eds), {Regional Geology of Eastern Idaho and Western Wyoming}, Geol Soc Amer Mem, 179: 227-267.

Kuntz M A, Spiker E C, Rubin M, Champion D E, Lefebvre R H, 1986. Radiocarbon studies of latest Pleistocene and Holocene lava flows of the Snake River Plain, Idaho: data, lessons, interpretations. Quat Res, 25: 163-176.

Stearns H T, Crandall L, Steward W G, 1938. Geology and ground-water resources of the Snake River Plain in southeastern Idaho. U S Geol Surv Water Supply Pap, 774: 1-268.

Volcano Types

Fissure vent(s)

Tectonic Setting

Rift zone
Continental crust (> 25 km)

Rock Types

Basalt / Picro-Basalt


Within 5 km
Within 10 km
Within 30 km
Within 100 km

Affiliated Databases

Large Eruptions of Hell's Half Acre 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.