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Myojinsho

Photo of this volcano
  • Japan
  • Caldera
  • 1970 CE
  •  
  • Country
  • Primary Volcano Type
  • Last Known Eruption
  •  
  • 31.888°N
  • 139.918°E

  • 11 m
    36 ft

  • 284070
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number
Most Recent Weekly Report: 25 January-31 January 2023 Citation IconCite this Report

According to JMA an area of pale yellow-green discolored water with a diameter of about 100 m was visible about 65 km SSE of Myojinsho on 26 January, based on an overflight conducted by the Japan Coast Guard. An eruption warning was issued to mariners. Discolored water was last observed in March 2018.

Sources: Japan Meteorological Agency (JMA), Japan Coast Guard


Most Recent Bulletin Report: March 1988 (SEAN 13:03) Citation IconCite this Report

Discolored water

Light green discolored water, centered over the vent in a fan-shaped zone ~8 km long, was seen from the air on 18 March. The next day, a circle of light green discolored water ~1.8 km in diameter was visible.

Information Contacts: JMA.

Weekly Reports - Index


2023: January
2018: March


25 January-31 January 2023 Citation IconCite this Report

According to JMA an area of pale yellow-green discolored water with a diameter of about 100 m was visible about 65 km SSE of Myojinsho on 26 January, based on an overflight conducted by the Japan Coast Guard. An eruption warning was issued to mariners. Discolored water was last observed in March 2018.

Sources: Japan Meteorological Agency (JMA); Japan Coast Guard


21 March-27 March 2018 Citation IconCite this Report

JMA issued a warning on 24 March for the waters surrounding Myojinsho after reports from the Japan Coast Guard indicated discolored water from a possible eruptive event.

Source: Japan Meteorological Agency (JMA)


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.

02/1970 (CSLP 10-70) Explosions and discolored water on 29 January; larger eruption on 3 February

03/1970 (CSLP 10-70) Explosions in January and February detected by hydrophones

04/1970 (CSLP 10-70) Eruption on 23 April sends water and smoke 200 m high

05/1970 (CSLP 10-70) Detailed observations of activity from fishing boats and observation flights

07/1970 (CSLP 10-70) Explosion bubbles and floating pumice on 18 June

07/1979 (SEAN 04:07) Water discoloration observed on 13 July 1979

11/1980 (SEAN 05:11) Discolored water

12/1980 (SEAN 05:12) Discolored water seen on 23 December

10/1987 (SEAN 12:10) Discolored water within 100 km

03/1988 (SEAN 13:03) Discolored water




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


February 1970 (CSLP 10-70)

Explosions and discolored water on 29 January; larger eruption on 3 February

Card 0859 (04 February 1970) Numerous explosions and discolored water on 29 January

The submarine volcano Myojin-sho exploded on 29 January between 1400 and 1600 hours. Located at 31°N, 139°59.5' E, the volcano shot a 200-300-m-wide water spout 100 m into the air at 1420, 1435, and 1443 hours. The explosions were accompanied by sulfur-colored smoke, as reported by the fishing boat Shintokumaru ##2. Another boat, the Shintokumaru ##12, reported five or six similar explosions, each of 3-4 minutes duration, at 1540 hours.

Card 0866 (13 February 1970) Larger eruption on 3 February

The Myojin-sho Reef in the Pacific erupted again at around 1040 [on 7 February], the 3rd Regional Maritime Safety Agency Headquarters in Yokohama revealed. The eruption was reported by the fishing boat No. 2 Shintoku Maru, which was sailing near the volcanic reef, located 150 km S of Hachijojima Island. According to the report, the eruption was greater in scale than the previous one which had occurred 29 January. Crew members of the fishing vessel witnessed great clouds of spray and seawater of dark-red color around the reef.

Information Contacts:
Card 0859 (04 February 1970) Tokiko Tiba, National Science Museum, Tokyo, Japan.
Card 0866 (13 February 1970) S. Motoda, Hokkaido University, Hakodate, Japan; W.H. Littlewood, American Embassy, Tokyo, Japan.


March 1970 (CSLP 10-70)

Explosions in January and February detected by hydrophones

Card 0880 (09 March 1970)

"The submarine eruption of Myojin-sho on 29 January was detected by sofar hydrophones of the Pacific Missile Range at Wake and Midway Islands. The origin time for the first explosion was 0330 GMT; for the last 1153 GMT. Eight large explosions occurred between 0330 and 0639, five between 0925 and 1012, and continuous high level activity between 1020 and 1110 GMT.

"Nine strong explosions from Myojin-sho originating between 0245 and 0511 GMT, 13 February, were recorded by the sofar hydrophones of the Pacific Missile Range at Wake and Midway. The hydrophones also recorded strong signals from the direction of Myojinsho on 14, 16 and 17 February with the strongest activity at 1044 GMT 17 February. One explosion was recorded on 25 February originating at 1914 GMT."

Information Contacts: Rockne H. Johnson, Hawaii Institute of Geophysics, University of Hawaii, USA.


April 1970 (CSLP 10-70)

Eruption on 23 April sends water and smoke 200 m high

Card 0927 (30 April 1970) Eruption on 23 April sends water and smoke 200 m high

The following information was passed to the Center via the American Embassy. Myojin-sho erupted again 23 April according to a report reaching Shizuoka from the Japanese fishing boat Kaigyo Maru of Izu, Shizuoka, Prefecture. The crew of the Kaigyo Maru witnessed the eruption at a point 50 km SE of the reef. It sent a column of water and smoke 200 m high.

Information Contacts: Japanese Fishing Fleet, Izu, Kyodo, Japan.


May 1970 (CSLP 10-70)

Detailed observations of activity from fishing boats and observation flights

Card 0938 (14 May 1970) Detailed observations of activity from fishing boats and observation flights

"The submarine volcano Myojin-sho exploded on 23 April 1970. Fishing boats, the Kairyu-maru and the 7th Kinosya-maru, reported as follows: 23 April, 0620 JST: explosion; water spout was given out 200-500 km high and about 100 m wide. 0630 -0637 JST: explosion. 0710 JST: explosion; volcanic smoke was observed to be 20-30 m high. After this, there were three to four explosions until 0800 hours on the same day. Water spout seemed to be higher than 200 m. The JMSA (Japan Maritime Safety Agency) observed the states of the submarine volcano from the air at 1125-1200 JST on 23 April and reported as follows: Sea water, about 100 m across, above the submarine volcano, was discolored by sulfur. A yellow belt of water discolored with sulfur, 1,000 m wide and 2,000 m long, moved in the SW direction from the discolored zone. At the front of this belt was a floating pumice zone 50-100 m wide and 1,000 m long, seemingly emitted on the occasion of the observed explosions. At 1100-1140 JST on 1 May, the members of JMA and JMSA observed this volcano from the air. No volcanic island above sea-level was seen, but light green sea water above the volcano suspended with sulfur or ejecta from the submarine-crater was observed (across 50-60 m). A discolored belt of water from this suspended zone was observed to move in the SE direction and to be 50-60 m wide, several hundred meters long. The sea temperature near this submarine volcano was measured with an infrared thermometer from the airplane but an extraordinary temperature was not detected."

Information Contacts: Yosihiro Sawada, Japan Meteorological Agency, Tokyo, Japan.


July 1970 (CSLP 10-70)

Explosion bubbles and floating pumice on 18 June

Card 0972 (15 July 1970) Explosion bubbles and floating pumice on 18 June

"In the morning of 18 June 1970, members of the fishing boat the 3rd Zinkokumaru observed the bubbles of a submarine volcanic explosion under sea-level about 50 m deep. Much pumice (max. 40 cm across) was floating near the sea surface above the submarine crater."

Information Contacts: Yosihiro Sawada, Japan Meteorological Agency, Tokyo, Japan.


July 1979 (SEAN 04:07) Citation IconCite this Report

Water discoloration observed on 13 July 1979

After 10 years of inactivity, discolored water was observed on 13 July 1979 at Myojin-sho.

Information Contacts: JMSA, Tokyo; JMA, Tokyo.


November 1980 (SEAN 05:11) Citation IconCite this Report

Discolored water

The crew of the fishing boat Suitenmaru 11 saw discolored water over Myojin-sho on 15 November at around 1530. They reported that no discoloration had been seen there that morning. JMSA personnel flew over the site on 18 November and observed three circular areas of pale green water, each 50-80 m across, aligned within a 300-m zone. [Discolored water was] also seen the following day by the crew of the fishing boat Shinkomaru 26 and again by JMSA personnel on 26 November. No floating ejecta or upwelling of water were noted, however.

Information Contacts: JMSA, Tokyo; JMA, Tokyo.


December 1980 (SEAN 05:12) Citation IconCite this Report

Discolored water seen on 23 December

The Japanese Maritime Safety Agency (JMSA) continues frequent aerial monitoring of several known submarine volcanoes. Renewed activity at Myojin-sho was first observed from a fishing boat on 15 November. [Overflights on 14 November and 18 December did not cover Myojin-sho, but that on 23 December observed discolored water at the site.]

Further Reference. Smoot, N.C., The growth rate of submarine volcanoes on the South Honshu and East Mariana Ridges: JGVR. [Bathymetric data on this and following seamounts throughout the Mariana arc.]

Information Contacts: JMA, Tokyo.


October 1987 (SEAN 12:10) Citation IconCite this Report

Discolored water within 100 km

Discolored water within a 100-m radius of Myojin-sho, the central cone of the submarine volcano, was recognized by observers on a fishing boat at 1040 on 21 October. No discolored water had been seen at 0603 that day and none was seen the next day during a JMSA overflight.

Information Contacts: JMA.


March 1988 (SEAN 13:03) Citation IconCite this Report

Discolored water

Light green discolored water, centered over the vent in a fan-shaped zone ~8 km long, was seen from the air on 18 March. The next day, a circle of light green discolored water ~1.8 km in diameter was visible.

Information Contacts: JMA.

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.

Eruptive History

There is data available for 15 confirmed Holocene eruptive periods.

[ 2023 Jan 26 - 2023 Jan 26 ] Uncertain Eruption

Episode 1 | Uncertain Episode
2023 Jan 26 - 2023 Jan 26 Evidence from Observations: Reported
 According to JMA an area of pale yellow-green discolored water with a diameter of about 100 m was visible about 65 km SSE of Myojinsho on 26 January 2023, based on an overflight conducted by the Japan Coast Guard. An eruption warning was issued to mariners.

List of 1 Events for Episode 1

Start Date End Date Event Type Event Remarks
2023 Jan 26    - - - - Observation Discolored water with a diameter of about 100 m.

[ 2018 Mar 24 - 2018 Mar 24 ] Uncertain Eruption

Episode 1 | Uncertain Episode
2018 Mar 24 - 2018 Mar 24 Evidence from Observations: Reported
 JMA issued a warning on 24 March 2018 for the waters surrounding Myojinsho after reports from the Japan Coast Guard indicated discolored water from a possible eruptive event.

List of 1 Events for Episode 1

Start Date End Date Event Type Event Remarks
2018 Mar 24    - - - - Observation Discolored water.

[ 1988 Mar 18 - 1988 Mar 19 ] Uncertain Eruption

Episode 1 | Eruption Episode Myojinsho
1988 Mar 18 - 1988 Mar 19 Evidence from Unknown

List of 1 Events for Episode 1 at Myojinsho

Start Date End Date Event Type Event Remarks
1988 Mar 18    - - - - VEI (Explosivity Index)

[ 1987 Oct 21 - 1987 Dec 9 ] Uncertain Eruption

Episode 1 | Eruption Episode Myojinsho
1987 Oct 21 - 1987 Dec 9 Evidence from Unknown

List of 1 Events for Episode 1 at Myojinsho

Start Date End Date Event Type Event Remarks
1987 Oct 21    - - - - VEI (Explosivity Index)

[ 1986 Oct 24 - 1986 Oct 24 ] Uncertain Eruption

Episode 1 | Eruption Episode Myojinsho
1986 Oct 24 - 1986 Oct 24 Evidence from Unknown

List of 1 Events for Episode 1 at Myojinsho

Start Date End Date Event Type Event Remarks
1986 Oct 24    - - - - VEI (Explosivity Index)

[ 1983 May 12 ] Uncertain Eruption

Episode 1 | Eruption Episode Myojinsho
1983 May 12 - Unknown Evidence from Unknown

List of 1 Events for Episode 1 at Myojinsho

Start Date End Date Event Type Event Remarks
1983 May 12    - - - - VEI (Explosivity Index)

[ 1982 Aug 10 ] Uncertain Eruption

Episode 1 | Eruption Episode Myojinsho
1982 Aug 10 - Unknown Evidence from Unknown

List of 1 Events for Episode 1 at Myojinsho

Start Date End Date Event Type Event Remarks
1982 Aug 10    - - - - VEI (Explosivity Index)

[ 1980 Nov 15 - 1980 Dec 23 ] Uncertain Eruption

Episode 1 | Eruption Episode Myojinsho
1980 Nov 15 - 1980 Dec 23 Evidence from Unknown

List of 1 Events for Episode 1 at Myojinsho

Start Date End Date Event Type Event Remarks
1980 Nov 15    - - - - VEI (Explosivity Index)

[ 1979 Jul 13 ] Uncertain Eruption

Episode 1 | Eruption Episode Myojinsho
1979 Jul 13 - Unknown Evidence from Unknown

List of 1 Events for Episode 1 at Myojinsho

Start Date End Date Event Type Event Remarks
1979 Jul 13    - - - - VEI (Explosivity Index)

[ 1971 Mar 18 ] Uncertain Eruption

Episode 1 | Eruption Episode
1971 Mar 18 - Unknown Evidence from Unknown

List of 1 Events for Episode 1

Start Date End Date Event Type Event Remarks
1971 Mar 18    - - - - VEI (Explosivity Index)

1970 Jan 29 - 1970 Jun 16 ± 15 days Confirmed Eruption Max VEI: 2

Episode 1 | Eruption Episode Myojinsho
1970 Jan 29 - 1970 Jun 16 ± 15 days Evidence from Observations: Reported

List of 4 Events for Episode 1 at Myojinsho

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Explosion
   - - - -    - - - - Pumice
   - - - -    - - - - Volcanic "smoke"
1970 Jan 29    - - - - VEI (Explosivity Index)

1960 Jul 21 Confirmed Eruption Max VEI: 2

Episode 1 | Eruption Episode Myojinsho
1960 Jul 21 - Unknown Evidence from Observations: Reported

List of 1 Events for Episode 1 at Myojinsho

Start Date End Date Event Type Event Remarks
1960 Jul 21    - - - - VEI (Explosivity Index)

1959 Jul 2 ± 182 days Confirmed Eruption Max VEI: 0

Episode 1 | Eruption Episode
1959 Jul 2 ± 182 days - Unknown Evidence from Observations: Reported

List of 1 Events for Episode 1

Start Date End Date Event Type Event Remarks
1959    - - - - VEI (Explosivity Index)

1958 Jul 2 ± 182 days Confirmed Eruption Max VEI: 0

Episode 1 | Eruption Episode
1958 Jul 2 ± 182 days - Unknown Evidence from Observations: Reported

List of 1 Events for Episode 1

Start Date End Date Event Type Event Remarks
1958    - - - - VEI (Explosivity Index)

1957 May 2 Confirmed Eruption Max VEI: 0

Episode 1 | Eruption Episode
1957 May 2 - Unknown Evidence from Observations: Reported

List of 1 Events for Episode 1

Start Date End Date Event Type Event Remarks
1957 May 2    - - - - VEI (Explosivity Index)

1955 Jun 25 Confirmed Eruption Max VEI: 0

Episode 1 | Eruption Episode 4 km north of Bayonnaise Rocks
1955 Jun 25 - Unknown Evidence from Observations: Reported

List of 1 Events for Episode 1 at 4 km north of Bayonnaise Rocks

Start Date End Date Event Type Event Remarks
1955 Jun 25    - - - - VEI (Explosivity Index)

1954 Nov 4 - 1954 Nov 5 Confirmed Eruption Max VEI: 0

Episode 1 | Eruption Episode Myojinsho
1954 Nov 4 - 1954 Nov 5 Evidence from Observations: Reported

List of 1 Events for Episode 1 at Myojinsho

Start Date End Date Event Type Event Remarks
1954 Nov 4    - - - - VEI (Explosivity Index)

1952 Sep 16 - 1953 Oct 16 ± 15 days Confirmed Eruption Max VEI: 2

Episode 1 | Eruption Episode Myojinsho
1952 Sep 16 - 1953 Oct 16 ± 15 days Evidence from Observations: Reported

List of 14 Events for Episode 1 at Myojinsho

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Explosion
   - - - -    - - - - Pyroclastic flow
   - - - -    - - - - Lava dome
   - - - -    - - - - Lava spine
   - - - -    - - - - Ash
   - - - -    - - - - Lapilli
   - - - -    - - - - Bombs
   - - - -    - - - - Pumice
   - - - -    - - - - Lightning
   - - - -    - - - - Island ephemeral
   - - - -    - - - - Tsunami
   - - - -    - - - - Property Damage
1952 Sep 16    - - - - VEI (Explosivity Index)
1952 Sep 24    - - - - Fatalities

1946 Feb 4 ± 4 days Confirmed Eruption Max VEI: 2

Episode 1 | Eruption Episode Island at 31.95 N 140.02 E
1946 Feb 4 ± 4 days - Unknown Evidence from Observations: Reported

List of 4 Events for Episode 1 at Island at 31.95 N 140.02 E

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Lava dome
   - - - -    - - - - Lava spine
   - - - -    - - - - Island ephemeral
1946 Feb 4 ± 4 days    - - - - VEI (Explosivity Index)

1934 May Confirmed Eruption Max VEI: 0

Episode 1 | Eruption Episode 9 km E of Bayonnaise Rocks
1934 May - Unknown Evidence from Observations: Reported

List of 1 Events for Episode 1 at 9 km E of Bayonnaise Rocks

Start Date End Date Event Type Event Remarks
1934 May    - - - - VEI (Explosivity Index)

1915 Feb - 1915 Jul Confirmed Eruption Max VEI: 0

Episode 1 | Eruption Episode 11 km east, 19 km NE, 4 km SW
1915 Feb - 1915 Jul Evidence from Observations: Reported

List of 3 Events for Episode 1 at 11 km east, 19 km NE, 4 km SW

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Explosion
   - - - -    - - - - Tsunami
1915 Feb    - - - - VEI (Explosivity Index)

1906 Apr 7 - 1906 Apr 14 Confirmed Eruption Max VEI: 1

Episode 1 | Eruption Episode 9-15 km SE of Bayonnaise Rocks
1906 Apr 7 - 1906 Apr 14 Evidence from Observations: Reported

List of 3 Events for Episode 1 at 9-15 km SE of Bayonnaise Rocks

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Explosion
   - - - -    - - - - Pumice
1906 Apr 7    - - - - VEI (Explosivity Index)

1896 Confirmed Eruption Max VEI: 2

Episode 1 | Eruption Episode 14 km north of Bayonnaise Rocks
1896 - Unknown Evidence from Observations: Reported

List of 2 Events for Episode 1 at 14 km north of Bayonnaise Rocks

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Island ephemeral
1896    - - - - VEI (Explosivity Index)

1871 Confirmed Eruption Max VEI: 0

Episode 1 | Eruption Episode Volcano Uncertain
1871 - Unknown Evidence from Unknown

List of 1 Events for Episode 1 at Volcano Uncertain

Start Date End Date Event Type Event Remarks
1871    - - - - VEI (Explosivity Index)

1869 May 6 Confirmed Eruption Max VEI: 0

Episode 1 | Eruption Episode Volcano Uncertain
1869 May 6 - Unknown Evidence from Unknown

List of 1 Events for Episode 1 at Volcano Uncertain

Start Date End Date Event Type Event Remarks
1869 May 6    - - - - VEI (Explosivity Index)
Deformation History

There is no Deformation History data available for Myojinsho.

Emission History

There is no Emissions History data available for Myojinsho.

Photo Gallery

An explosion from the Beyonesu Rocks at the Myjinsho submarine caldera in Japan's central Izu Islands breaches the sea surface on 23 September 1952. These cock’s tail jets of blocks and ash are characteristic of shallow submarine explosions. This photo was taken 5 seconds after the explosion breached the sea surface; five minutes later the eruption was over and the sea was again calm. The suddenness of these powerful explosions proved to be fatal to 31 people on a research vessel that sailed over the vent the following day.

Photo courtesy of Ryohei Morimoto (University of Tokyo), 1952.
A submarine eruption at Myojinsho lava dome on the rim of Beyonesu Rocks caldera in the central Izu Islands on 23 September 1952. This photo shows a vertically rising plume of ash and steam (cocks’s-tail plume) and a base surge traveling across the sea surface. This photo was taken 8 seconds after the explosion first breached the surface. The eruption began on 16 September when a lava dome rose towards the sea surface. Explosive activity then progressively destroyed the dome. This cycle occurred three times until October 1953.

Photo courtesy of Ryohei Morimoto (University of Tokyo).
Steam emission from the blocky summit of a lava dome formed during a submarine eruption at the Beyonesu Rocks vent of the Myojinsho caldera in 1952. This 22 September photo was taken six days after the dome began to breach the sea surface. Later that day the eruption became highly explosive and the dome was destroyed. Three cycles of dome growth and destruction occurred until October 1953.

Photo courtesy of Helen Foster, 1952 (U.S. Geological Survey).
GVP Map Holdings

The maps shown below have been scanned from the GVP map archives and include the volcano on this page. Clicking on the small images will load the full 300 dpi map. Very small-scale maps (such as world maps) are not included. The maps database originated over 30 years ago, but was only recently updated and connected to our main database. We welcome users to tell us if they see incorrect information or other problems with the maps; please use the Contact GVP link at the bottom of the page to send us email.

Smithsonian Sample Collections Database

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

External Sites