Emergency Measures for Protecting the "Oki-no-Tori-Shima" Island agaist waves
Outlined here is a current focal issue related with a Japan's uninhabited island of coral reef (semi-table reef in
terms of topography, ellipse-shaped, about 1.7 km long in diameter and 11 km round at ebb tide(1)) lying in the west
Pacific. The island is named "Oki-no-Tori-Shima" in Japanese, which is the Japan's southernmost one (location: 200
25' N. latitude, 1360 05' E. longitude)(2), about 2,000 km south of Tokyo.
A crucial issue has been raised as a result of the recent observations made by its competent authorities. That is,
only two small rocks (upheaved limestones) lie above sea level at high tide: As shown in
attached Figures 1, one rock is merely 4.7 m wide and 3 m high and another is 2.6 m wide and 1 m high.(3) And, both
rocks are nowadays mushroom-shaped due to the longstanding abrasions by waves.
In accordance with the Law on Privisional Measures Relating to the Fishing Zone, enforced on July 1, 1977, Japan extends
its fishery jurisdiction in its surrounding waters up to 200 miles from the baselines from which the territorial seas are
measured. The 200-mile fishing zone's jurisdiction in waters surrounding the island is to cover a total area of about
400,000 km2. This maritime zone is considerably larger in area than the total land of the country's own.
A most serious issue which the government most fears to occur is: For isntance, if the rocks fell fall down
and did not lie above sea level, it would fail to claim its excludive jurisdiction related to not only the continental
shelf but a 200-mile exclusive economic zone (EEZ) in waters around them.
Despite such a foreseeable claim of the government, the 1982 UNCLOS provides that:
- An island is a naturally formed area of land, surrounded by water, which is above water at high tide
(Paragraph 1 of Article 121).
- Rocks which cannot sustain human habitation or economic life of their own shall have no exclusive economic zone or
continental shelf (Paragraph 3 of Article 121).
The government has proceeded to an emergency measures for the purpose of territorial integrity since
1987 of Japanese fiscal year (JFY). As shown in attached Figures 2, as one of the planned protection methods,(4)
(1) A wall of antiwave steel-made blocks is constructed as a breakwater in waters around each rock (The round-shaped
wall is 50 m in diameter).
(2) The inside of the wall is filled with special underwater concrete. Thus, the foot of each mushroom-shaped rock
is consolidated firmly.
The island's topographical situation in future must be determined principally by the following natural conditions'
interaction: rises and falls of not only corals but bedrocks lying beneath them, and abrasion by waves.
Thus, another important issue is raised. That is, such a protection or reinforcement measures might have a gravely adverse
effect on the island in the long run, i.e. leading it to a submerged sea mount by destroying the corals.
[Footnotes](1), (2) and (3): Japanese daily newspaper "Nihon Keizai Shimbun", September 3, 1987.
(4) Ibid., November 27, 1987.
The Oki-no-Tori-Shima's rock-protection works having been carried out with a multibillion dollar budget of the Japanese
government since the spring of 1988 were eventually accomplished at the beginning of November 1989. If the island is left
as it is, there remains nothing but two tiny mushroom-shaped rocks (named "Hokuro-gan" and "Touro-gan") which project
their tops several meters above sea level at flood tide. Accordingly, each of the rocks was double-embanked circlewise
with heavy steel-made tetrapods totaling 9,900 pieces as a prime measure for protecting them against wave erosion.
The total expenditure for the works amounted to \28.5 billion equivalent to more or less US＄200 million. Some marine scientific
observation-purpose instruments, e.g. tide gauge, were installed on the concrete structures. The neck of each rock had been washed persistently and eroded
gradually by waves. Those rock-protection works have been based on the following belief of the gavernment: any legal grounds for justifying its
claim over a 200-mile zone around the island, the sea area of which amounts to about 400,000 km2 and is no less than
the country's total land area (that is, about 370,000 km2), would be no longer maintained at all if both of them happened
to fall down and come to submerge completely at flood tide.
Figure: Oki-no-Tori-Shima Island and Protection Measures
1. Section of Two Mushroom-shaped Rocks of Oki-no-Tori-Shima. Source: Japanese daily newspaper,
Nihon Keizai Shimbun, September 3, 1987. [拡大画像: x28618.jpg]
2. A Plan of Civil Works for Territorial Integrity of the Oki-no-Tori-Shima Island. Source: Japanese daily newspaper,
Asahi Shimbun, November 27, 1987. [拡大画像: x28619.jpg]
3. Asahi Shimbun, June 3, 1988. [拡大画像: x28617.jpg]
Source of English Version： Research report "Japan Ocea Affairs － Ocen Regime, Policy and Development －,
7th edition updated and revised on Decenmer 31, 1989, authored by Kiyofumi Nakauchi in cooperation with the Law of the
Sea Institute Japan. However, the English version was reviewed grammatically for "One Selected Photo 'Oceans & Ships'"
on May 24, 2020.|
英語版出典： 研究報告書「日本の海洋政策 －海洋制度、政策、開発－」、1989年12月31日改編版(第7版)、中内清文著、海洋法研究所発行。(注:
2020年5月24日に「一枚の特選フォト「海 ＆ 船」」掲載時に、文法上の部分修正を加える)。