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  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 41.51°N
  • 139.367°E

  • 732 m
    2401 ft

  • 285010
  • Latitude
  • Longitude

  • Summit

  • Volcano

The Global Volcanism Program has no activity reports for Oshima-Oshima.

The Global Volcanism Program has no Weekly Reports available for Oshima-Oshima.

Index of Monthly Reports

Reports are organized chronologically and indexed below by Month/Year (Publication Volume:Number), and include a one-line summary. Click on the index link or scroll down to read the reports.

03/1996 (BGVN 21:03) Earthquakes and tremor detected

Contents of Monthly Reports

All information contained in these reports is preliminary and subject to change.

03/1996 (BGVN 21:03) Earthquakes and tremor detected

Volcanic earthquakes and tremors were detected near the end of March by instruments maintained by Hokkaido University.

This small island 55 km W of Hokkaido in the Japan Sea consists of two coalescing volcanoes. An eruption in August 1741 produced heavy ashfall on the Hokkaido mainland. A violent explosion and landsliding from the Nishi-yama cone accompanied a large tectonic earthquake and a major tsunami that killed 1,475 people, most on the W coast of the Oshima Peninsula. Subsequent eruptions through early 1742 produced a new central cone and lava flows. Minor explosive activity was documented in 1759, 1786, and 1790.

Information Contacts: Volcanological Division, Seismological and Volcanological Department, Japan Meteorological Agency (JMA), 1-3-4 Ote-machi, Chiyoda-ku, Tokyo 100 Japan.

Oshima-Oshima, a small, 4-km-wide Japan Sea island 55 km west of the SW tip of Hokkaido, is the emergent summit of two coalescing basaltic-to-andesitic stratovolcanoes. Higashiyama, at the east end of the island, is cut by a 2-km-wide caldera covered on its west side by Nishiyama volcano. The western cone failed during an eruption in 1741, creating a large horseshoe-shaped caldera breached to the north that extends from the summit down to the sea floor at the base of the volcano and producing a mostly submarine debris avalanche that traveled 16 km. A tsunami associated with the collapse swept the coasts of Hokkaido, western Honshu, and Korea, and caused nearly 1500 fatalities. The 1741 eruption, the largest in historical time at Oshima-Oshima, concluded with the construction of a basaltic pyroclastic cone at the head of the breached caldera. No eruptions have occurred since the late-18th century.

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

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
1790 Jan (?) Unknown Confirmed 2 Historical Observations Nishi-yama
[ 1786 ] [ Unknown ] Uncertain 2   Nishi-yama
1759 Aug 19 Unknown Confirmed 2 Historical Observations Nishi-yama
1741 Aug 18 (?) 1742 May Confirmed 4 Historical Observations Nishi-yama
0250 ± 150 years Unknown Confirmed   Radiocarbon (uncorrected) Nishi-yama
0800 BCE ± 100 years Unknown Confirmed   Radiocarbon (uncorrected) Nishi-yama

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.

O-sima | Osima-Osima

Feature Name Feature Type Elevation Latitude Longitude
Higashi-yama Stratovolcano 737 m
Kanpo-dake Cinder cone 680 m
Nishi-yama Stratovolcano 722 m
Oshima-Oshima volcano is seen here from the north with Kanpo-dake, the pyroclastic cone formed following the 1741 eruption on the center horizon. Major edifice collapse in that year produced a large horseshoe-shaped caldera open to the north, whose walls are visible at the sides of the image. Oshima-Oshima, a small, 4-km-wide Japan Sea island 55 km west of the SW tip of Hokkaido, is the emergent summit of two coalescing stratovolcanoes, Higashi-yama, at the east end of the island, and Nishi-yama at the west end.

Copyrighted photo by Tomoyo Hayakawa (Japanese Quaternary Volcanoes database, RIODB, http://riodb02.ibase.aist.go.jp/strata/VOL_JP/EN/index.htm and Geol Surv Japan, AIST, http://www.gsj.jp/).

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.

Fujitani T, Masuda A, 1982. Wholly compatible and complementary patterns of rare-earth elements in Quaternary volcanic rocks from Oshima-Oshima and Oshima-Kojima isles, Japan. Geochem J, 16: 23-31.

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

Katsui Y, Yamamoto M, 1981. The 1741-1742 activity of Oshima-Oshima volcano, north Japan. Hokkaido Univ Fac Sci J, 19: 527-536.

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, http://riodb02.ibase.aist.go.jp/db099/eruption/index.html.

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, http://www.aist.go.jp/RIODB/strata/VOL_JP/.

Satake K, Kato Y, 2001. The 1741 Oshima-Oshima eruption: extent and volume of submarine debris avalanche. Geophys Res Lett: 28: 427-430.

Volcano Types

Pyroclastic cone

Tectonic Setting

Subduction zone
Continental crust (> 25 km)

Rock Types

Basalt / Picro-Basalt
Andesite / Basaltic Andesite


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

Affiliated Databases

Large Eruptions of Oshima-Oshima 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.