Oshima-Oshima

Photo of this volcano
  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 41.51°N
  • 139.367°E

  • 732 m
    2401 ft

  • 285010
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number

Most Recent Bulletin Report: March 1996 (BGVN 21:03) Citation IconCite this Report


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.

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

Bulletin Reports - Index


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




Information is preliminary and subject to change. All times are local (unless otherwise noted)


March 1996 (BGVN 21:03) Citation IconCite this Report


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.

Eruptive History


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.

Photo Gallery


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/).
See title for photo information.

Smithsonian Sample Collections Database


The following 2 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 112974 Hornblende basalt
NMNH 112975 Olivine-basalt

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