BAYONNAISE ROCKS (ベヨネース列岩, Beyonēsu-retsugan) is a
group of volcanic rocks in the
Philippine Sea about 408 kilometres
(254 mi) south of
Tokyo and 65 kilometres (40 mi) south-southeast of
Aogashima , in the south portion of the Izu archipelago ,
Japan . The
rocks were discovered by the French corvette Bayonnaise in 1850 while
surveying the island south of
Tokyo Bay .
* 1 Geography
* 2 See also
* 3 References
* 4 External links
The rocks are the exposed portion of the western ridge of a submarine
volcanic caldera , approximately 9 kilometres (5.6 mi) in diameter at
a depth of approximately 1,000 metres (3,300 ft). The above sea-level
portion has a surface area of approximately 0.01 square kilometers,
with a summit height of 11 metres (36 ft). and consists of three large
rocks and many smaller rocks.
The caldera is known to have erupted in 1869, 1870, 1871, 1896, 1906,
1915, 1934, 1946, 1952-1953, 1954, 1955, 1957, 1958, 1959, 1960, and
1970. The last known submarine eruption of the caldera was in 1988,
which discolored the local water.
On the northeast rim of the same caldera 12.8 kilometres (8.0 mi) to
the east of the
Bayonnaise Rocks is a submerged reef named
Myōjin-shō (明神礁), which is a post-caldera cone with a depth of
approximately 50 metres (160 ft). During a submarine volcanic eruption
of 17 September 1952, an ephemeral island was formed, with a height of
10 metres (33 ft), which was created and destroyed several times by
volcanic activity until completely disappearing on 23 September 1953.
The following day, an eruption killed 31 researchers and crewmen
abroad the Maritime Safety Agency survey ship No.5 Kaiyo-Maru. The
island reappeared on 11 October, sinking again on 11 March 1954 and
reappeared one more time between 5 April and 3 September 1954.
Vegetation is sparse among the Bayonnaise Rocks. The islands are a
resting place for migratory birds . Located in the
Kuroshio Current ,
the area has abundant sea life, and is popular with sports fishermen.
* ^ A B C D "66. Beyonesu (Bayonnaise) Rocks (including Myojinsho)"
Japan Meteorological Agency. Retrieved 26 March 2017.
* ^ Christopher G. Newhall, Daniel Dzurisin: Historical Unrest at
large Calderas of the World. Volume 1, U.S. Geological Survey Bulletin
1855, Washington 1988, p. 506; Bathymetric map around "Bayonnaise
Rocks" based on Basic Map of the Sea (1:50.000, retrieved 2012-12-13).