Omanago Group

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  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 36.792°N
  • 139.51°E

  • 2367 m
    7764 ft

  • 283142
  • Latitude
  • Longitude

  • Summit

  • Volcano

The Global Volcanism Program has no activity reports for Omanago Group.

The Global Volcanism Program has no Weekly Reports available for Omanago Group.

The Global Volcanism Program has no Bulletin Reports available for Omanago Group.

Volcano Types

Lava dome(s)

Tectonic Setting

Subduction zone
Continental crust (> 25 km)

Rock Types

Andesite / Basaltic Andesite


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

Geological Summary

The Omanago volcano group consists of a series of five closely spaced lava domes that were constructed north and NW of Nantai volcano in Nikko National Park. The highest of the dacitic domes is 2367-m-high Omanago, which later erupted andesitic lavas. Mitsu-dake lava dome, which overlooks the hot spring resort of Lake Yunoko, was radioarbon dated at about 5000 years ago. Mitsu-dake was constructed on a southerly dipping slope, so that the southern of its two flat-topped domes is lower, and is overlapped by sediments of the Senjogahara plain.

Eruptive History

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

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
3050 BCE (?) Unknown Confirmed   Radiocarbon (uncorrected) Mitsu-dake

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.


Feature Name Feature Type Elevation Latitude Longitude
Komanago Dome 2323 m
Mitsu-dake Dome 1945 m
Sanno-Boshi Dome 2073 m
Taro Dome 2368 m

Photo Gallery

The Omanago volcano group (upper left) consists of a series of five closely spaced lava domes in Nikko National Park. The highest of the dacitic domes is 2367-m-high Omanago, located at the SE end of the complex. Mitsu-dake, the NW-most dome, is a complex lava dome. The higher northern peak of the Mitsu-dake complex is out of view to the left, and the lower southern dome forms the low ridge behind the hot spring resort of Yunoko lake in the center of the photo. The prominent peak on the right horizon is Nantai volcano.

Photo by Lee Siebert, 1964 (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.

Hayakawa Y, 2009. . (pers. comm.).

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

Japan Association Quaternary Research, 1987. Quaternary Maps of Japan: Landforms, Geology, and Tectonics. Tokyo: Univ Tokyo Press.

Nakano S, Yamamoto T, Iwaya T, Itoh J, Takada A, 2001-. Quaternary Volcanoes of Japan. Geol Surv Japan, AIST,

Ono K, Soya T, Mimura K, 1981. Volcanoes of Japan. Geol Surv Japan Map Ser, no 11, 2nd edition, 1:2,000,000.

Tsuboi S, Sugi K, 1926. Geological guide to the Nikko district. Pan-Pacific Sci Cong Guidebook Excur, B-1: 4-25.

Yamasaki M, 1981. Nantai and adjacent volcanoes in the Nikko region. In: Aramaki S (ed) {Symp Arc Volcano Field Excur Guide to Fuji, Asama, Kusatsu-Shirane and Nantai Volcanoes}, Tokyo: Volc Soc Japan, 1: 64-75,.

Affiliated Databases

Large Eruptions of Omanago Group 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.