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Continental Shelf


Continental Shelf  (CS) refers to the part of the seabed sloping gently between the coast and the deep ocean.

Geographically and legally the definition of the Continental Shelf is different from the Exclusive Economic Zone (EEZ)


The Continental Shelf is the sub-sea extension of the continent where the waters are still shallow, between 150 and 200 meters deep, compared to deep water and ultra deep waters, with several thousands meters of depth.

Between the Continental Shelf and the deep ocean, there are still two zones, the Continental Slope and the Continental Rise.

The Continental Slope is the part where the seabed goes down steeply from the Continental Shelf to the deep waters.

The Continental Rise is at the foot of the Continental Slope where the seabed accumulates sediments falling from the slope giving to the seabed again a gentle slope profile within deep or ultra deep waters.

Around the continents, the width of the Continental Shelf vary from 20 to 500 kilometers.

These Continental Shelf areas have taken an up most importance on the last years because the shallow waters above the Continental Shelf are normally rich of seafood and make easy to reach the resources laying within the Continental Shelves, such as oil and gas.

Because many countries wanted to develop these resources for food or energy purpose, the United Nations, Oceans & Law of the Sea (UNCLOS) published on August 29th, 1980 the definition of the Continental Shelf and criteria  for the establishment of its outer limits.

Within this document, the Continental Shelf takes a legal dimension as described in the Article 76, paragraphs 4-7 of the Convention

“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”.

In this article the specified 200 nautical miles do match with the 200 nautical miles such as defined in the Article 55 of this United Nations Convention on the Law of the Sea , for the limits of the maritime Exclusive Economic Zone (EEZ).

Unfortunately the Continental Shelf may go geographically far beyond these EEZ 200 nautical miles, for example in USA it can reach 400 miles.

Therefore the Convention had to provide with an additional definition on the Continental Shelf to consider its extension  in some cases up to 350 nautical miles from the baselines from which the breadth of the territorial sea.

Within this legal definition of the Continental Shelf, the Article 77 gives rights to the coastal States, to explore and exploite the natural resources.

Regarding the oil and gas sector, the most active regions using these rights in shallow waters are the:

 – North Sea, divided between the UK’s Continental Shelf (UKCS) and the Norway’s Continental Shel (NCS)

 – All countries around the South China Sea (Brunei, China, Malaysia, Philippines, Vietnam)

 – USA

 – Australia and New Zeland

The Continental Shelf, the Territorial Waters and the EEZ follow different legal definitions according to the United Nations, Oceans & Law of the Sea (UNCLOS).

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