Bayonnaise Rocks Volcano - John Seach


(Myojin-sho, Myozin-syo, Myozin-reef, Myojin Reef)
Izu Islands, Japan

31.92 N, 139.92 E
summit elevation 11 m
submarine volcano

Bayonnaise Rocks volcano is located in the Izu Islands, 400 km south of Tokyo. The volcano barely rises above the surface of the sea. Most eruption have occurred at Myojin-sho in the NE of the caldera.

1952-53 Eruption
The eruption of Myozin-syo, Bayonnaise rocks volcano, was the most notable eruption in Japan during the years 1951-1954. The eruption was first reported by on 17th September 1952 by crew of the fishing boat Myozin-maru No. 11. The eruption occurred at Myozin-syo dome, 30 km NNE of Bayonnaise Rocks. Eruptions from the volcano formed a temporary island 150 m long, 100 m wide and 30 m high. The island disappeared under the water on 23rd September. On 24th September a 2 m high tsunami was produced by eruptions.

Kaiyo-maru No. 5 Disaster
Kaiyo-maru No. 5, was a ship for marine observation, belonging to the Hydrographic Office of the Maritime Safety Board in Japan. The ship sailed from Tokyo on 23rd September 1952 to resurvey the submarine topography in the vicinity of the eruption. The ship seems to have capsized suddenly owing to a close range approach to a submarine eruption at 12h 30 m on 24th September 1952. There were no eye-witnesses to the tragedy, and all 31 lives on board were lost. A tide gauge at Hatizyo-sima Weather Station, 120 km north Myozin-syo, recorded a tsunami at 12h 53 m, which had traveled for 28 minutes from the volcano. US Navy hydrophones in Hawaii measured underwater sounds from the explosions.

Wreckage of the Kaiyo-maru No. 5, drifted on the ocean current, and was found on from 25th to 28th of September, south of Bayonnaise Rocks volcano. Pieces of fragmental lava and pumice were found stuck into the wreckage, and this matched with samples from the volcano.

1906 Eruption
A submarine eruption occurred near Bayonnaise Rocks between 7-13 April 1906. A large amount of pumice was found floating on the sea.

Bayonnaise Rocks Volcano Eruptions

1970, 1960, 1959, 1958, 1957, 1955, 1954, 1952-53, 1946, 1934, 1915, 1906, 1896.

Possible eruptions occurred in 1988, 1987, 1986, 1983, 1980, 1979, 1971