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  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 36.891°N
  • 138.114°E

  • 2454 m
    8049 ft

  • 283100
  • Latitude
  • Longitude

  • Summit

  • Volcano

The Global Volcanism Program has no activity reports for Myokosan.

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

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

Basic Data

Volcano Number

Last Known Eruption



750 BCE

2454 m / 8049 ft


Volcano Types

Lava dome

Rock Types

Andesite / Basaltic Andesite
Basalt / Picro-Basalt

Tectonic Setting

Subduction zone
Continental crust (> 25 km)


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

Geological Summary

Myokosan is a steep-sided stratovolcano north of Nagano City that overlooks the popular resort of Lake Nojiri below its SE flank. A 3-km-wide caldera breached widely to the east is filled by a flat-topped lava dome that forms the basaltic-to-dacitic volcano's summit. It was constructed during four stages beginning about 300,000 years ago, each evolving from basaltic to andesitic and dacitic eruptions. The latest eruptive stage began about 43,000 years ago. Several episodes of edifice collapse during the late Pleistocene to early Holocene have produced major debris avalanches that traveled to the east and NE. Pyroclastic flows traveled down the eastern flanks during the mid-Holocene about 5800 and 4200 years ago, and the latest dated eruption produced pyroclastic surges about 2800-2500 years ago. No historical eruptions are known at Myokosan, but constant solfataric activity occurs between the dome and the south caldera wall at a place where sulfur was once mined.


The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography.

Hayatsu K, 1976. Geologic study on the Myoko volcanoes, central Japan - Part 1. Stratigraphy. Kyoto Univ Ser Geol Min, 42: 131-170.

Hayatsu K, 1985. Myoko volcano group - its geology and history. Tokyo: Daiichi-Shuppan, 344 p (in Japanese).

Hayatsu K, Arai F, 1980. Tephrochronological study on the Myoko volcano tephra layers and their relation to activity of the volcano. J Geol Soc Japan, 86: 243-263 (in Japanese with English abs).

Hayatsu K, Shimizu S, Itaya T, 1994. Volcanic history of the Myoko volcano group, central Japan; a poly-generation volcano. J Geogr, 103: 207-220 (in Japanese with English abs).

Japan Meteorological Agency, 1996. National Catalogue of the Active Volcanoes in Japan (second edition). Tokyo: Japan Meteorological Agency, 502 p (in Japanese).

Japan Meteorological Agency, 2013. National Catalogue of the Active Volcanoes in Japan (fourth edition, English version). Japan Meteorological Agency.

Kawachi S, Hayatsu K, 1994. Debris avalanche and lahar deposits in the Yatsugatake volcanic chain and Myoko volcano, central Japan. J Nat Disaster Sci, 16: 55-69.

Kudo T, Hoshizumi H, 2006-. Catalog of eruptive events within the last 10,000 years in Japan, database of Japanese active volcanoes. Geol Surv Japan, AIST,

Kuno H, 1962. Japan, Taiwan and Marianas. Catalog of Active Volcanoes of the World and Solfatara Fields, Rome: IAVCEI, 11: 1-332.

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

Eruptive History

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

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
0750 BCE Unknown Confirmed   Tephrochronology
1200 BCE (?) Unknown Confirmed   Tephrochronology
2100 BCE ± 500 years Unknown Confirmed   Tephrochronology
2750 BCE ± 100 years Unknown Confirmed 4 Radiocarbon (corrected) Otagirigawa Ash; OT-a tephra
2900 BCE (?) Unknown Confirmed   Tephrochronology
3450 BCE (?) Unknown Confirmed   Tephrochronology
3700 BCE (?) Unknown Confirmed   Tephrochronology
4000 BCE (?) Unknown Confirmed   Tephrochronology
4300 BCE (?) Unknown Confirmed   Tephrochronology
4750 BCE ± 300 years Unknown Confirmed 5 Radiocarbon (corrected) Akakura Ash; AK-a 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.




Feature Name Feature Type Elevation Latitude Longitude


Feature Name Feature Type Elevation Latitude Longitude
Akakura Thermal
Tsubame Thermal

Photo Gallery

Myoko is a steep-sided stratovolcano in west-central Honshu that overlooks the popular resort of Lake Nojiri. This springtime view from Madarao, SE of Myoko, shows a 3-km-wide caldera breached to the east that is partially filled by a flat-topped lava dome forming the volcano's high point. Several episodes of edifice collapse at Myoko have produced major debris avalanches that traveled to the east and NE. The latest dated eruptions of Myoko occurred during the mid Holocene. No historical eruptions are known, but constant solfataric activity occurs.

Photo by Yukio Hayakawa, 1998 (Gunma University).

Smithsonian Sample Collections Database

There are no samples for Myokosan in the Smithsonian's NMNH Department of Mineral Sciences Rock and Ore collection.

Affiliated Sites

Large Eruptions of Myokosan 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).
MODVOLC - HIGP MODIS Thermal Alert System Using infrared satellite Moderate Resolution Imaging Spectroradiometer (MODIS) data, scientists at the Hawai'i Institute of Geophysics and Planetology, University of Hawai'i, developed an automated system called MODVOLC to map thermal hot-spots in near real time. For each MODIS image, the algorithm automatically scans each 1 km pixel within it to check for high-temperature hot-spots. When one is found the date, time, location, and intensity are recorded. MODIS looks at every square km of the Earth every 48 hours, once during the day and once during the night, and the presence of two MODIS sensors in space allows at least four hot-spot observations every two days. Each day updated global maps are compiled to display the locations of all hot spots detected in the previous 24 hours. There is a drop-down list with volcano names which allow users to 'zoom-in' and examine the distribution of hot-spots at a variety of spatial scales.
MIROVA Middle InfraRed Observation of Volcanic Activity (MIROVA) is a near real time volcanic hot-spot detection system based on the analysis of MODIS (Moderate Resolution Imaging Spectroradiometer) data. In particular, MIROVA uses the Middle InfraRed Radiation (MIR), measured over target volcanoes, in order to detect, locate and measure the heat radiation sourced from volcanic activity.