2.3 Definition of Continental Shelf Within and Beyond
200 nm
UNCLOS Part VI positivizes rules and principles applicable to the continental shelf,
a juridical definition of which is provided straightforwardly by Art. 76 (1):
The continental shelf of a coastal State comprises the seabed and subsoil of the submarine
areas that extend beyond its territorial sea throughout the natural prolongation of its land
territory to the outer edge of the continental margin, or to a distance of 200 nautical miles
from the baselines from which the breadth of the territorial sea is measured where the outer
edge of the continental margin does not extend up to that distance (emphasis added).
34
It is juridical, for it does not coincide with the strictly geologic or geomorphological characteristics of the shelf.
35 From this definition, some expressions stand
out, namely “natural prolongation”, “continental margin” and “or” (used in order to
mark an alternative to the first, essentially geological, concept of continental shelf),
which mark the complex interdisciplinarity of the continental shelf regime, and the
entangled relationship between law and science in this particular regard. In order to
understand the legal concept of continental shelf, one must be familiar with the
geographical notion of “continental margin”. As such, the margin consists of “the
seabed and subsoil of the shelf, the slope and the rise”, excluded the deep ocean floor
and its oceanic ridges or subsoil.
36
An authoritative definition was provided by the International Court of Justice
(ICJ) in the North Sea Continental Shelf cases, in which the continental shelf was
described as
the natural prolongation of its land territory under the sea exist ipso facto and ab initio by
virtue of the State’s sovereignty over the land and by extension of that sovereignty in the
form of the exercise of sovereign rights for the purposes of the exploration of the seabed and
the exploitation of its natural resources.
37
A key development in the continental shelf regime established by UNCLOS is the
possibility given to broad-margin coastal states to exercise rights over a submerged
area stretching out beyond 200 nm from the baselines. Such area is still labelled as
“continental shelf”, but due to some particularities, it has also been tagged outer
continental shelf by academic works in the field. A definition for that “extra” seafloor
describes the outer continental shelf as “the area of sea-bed and subsoil ranging from
the 200-nm EEZ limit to the seaward limit of the legal continental shelf, incorporating the geological continental shelf, rise, slope and margin but not including the
34 UNCLOS Art. 76, paragraph 1, on the definition of the continental shelf.
35 A geological definition of the continental shelf describes it as a strip of submerged land existing
on the entire coast of every continent, which, on a gradual inclination, stretches seaward until the
continental slope.
36 UNCLOS Art. 76, paragraph 3, still on the definition of the continental shelf.
37 ICJ North Sea Continental Shelf Cases, judgment of 20 February 1969, Reports, 1969, 3, para 19.
28
2 The General International Legal Regime of the Continental Shelf
200 nm
UNCLOS Part VI positivizes rules and principles applicable to the continental shelf,
a juridical definition of which is provided straightforwardly by Art. 76 (1):
The continental shelf of a coastal State comprises the seabed and subsoil of the submarine
areas that extend beyond its territorial sea throughout the natural prolongation of its land
territory to the outer edge of the continental margin, or to a distance of 200 nautical miles
from the baselines from which the breadth of the territorial sea is measured where the outer
edge of the continental margin does not extend up to that distance (emphasis added).
34
It is juridical, for it does not coincide with the strictly geologic or geomorphological characteristics of the shelf.
35 From this definition, some expressions stand
out, namely “natural prolongation”, “continental margin” and “or” (used in order to
mark an alternative to the first, essentially geological, concept of continental shelf),
which mark the complex interdisciplinarity of the continental shelf regime, and the
entangled relationship between law and science in this particular regard. In order to
understand the legal concept of continental shelf, one must be familiar with the
geographical notion of “continental margin”. As such, the margin consists of “the
seabed and subsoil of the shelf, the slope and the rise”, excluded the deep ocean floor
and its oceanic ridges or subsoil.
36
An authoritative definition was provided by the International Court of Justice
(ICJ) in the North Sea Continental Shelf cases, in which the continental shelf was
described as
the natural prolongation of its land territory under the sea exist ipso facto and ab initio by
virtue of the State’s sovereignty over the land and by extension of that sovereignty in the
form of the exercise of sovereign rights for the purposes of the exploration of the seabed and
the exploitation of its natural resources.
37
A key development in the continental shelf regime established by UNCLOS is the
possibility given to broad-margin coastal states to exercise rights over a submerged
area stretching out beyond 200 nm from the baselines. Such area is still labelled as
“continental shelf”, but due to some particularities, it has also been tagged outer
continental shelf by academic works in the field. A definition for that “extra” seafloor
describes the outer continental shelf as “the area of sea-bed and subsoil ranging from
the 200-nm EEZ limit to the seaward limit of the legal continental shelf, incorporating the geological continental shelf, rise, slope and margin but not including the
34 UNCLOS Art. 76, paragraph 1, on the definition of the continental shelf.
35 A geological definition of the continental shelf describes it as a strip of submerged land existing
on the entire coast of every continent, which, on a gradual inclination, stretches seaward until the
continental slope.
36 UNCLOS Art. 76, paragraph 3, still on the definition of the continental shelf.
37 ICJ North Sea Continental Shelf Cases, judgment of 20 February 1969, Reports, 1969, 3, para 19.
28
2 The General International Legal Regime of the Continental Shelf