GEO ExPro

Mapping the Seafloor

GEBCO plans a comprehensive mapping of the entire ocean floor.
This article appeared in Vol. 13, No. 6 - 2017

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It has been said that our present world view and comprehension of the Earth’s processes is a direct result of mapping and understanding the nature of the seafloor (Dierssen and Theberge, 2015).

Early (1752) bathymetric and geologic map of the English Channel area by Philippe Buache. (Source: NOOA Photo Library) Sailors have always needed to know how far the seabed lay beneath the keel of their boat and for centuries used a ‘line and sinker’ – a marked rope or wire with a lead weight, dropped over the side of a boat - to measure the distance to the seafloor, but few of these measurements were kept for posterity. In the early 19th century, however, partially spurred by the desire to lay deep sea telegraph cables, national navies and other bodies started to record detailed depth soundings, using them to build maps of the seafloor. Much to their surprise, these revealed that deep beneath the oceans the seabed was not flat and featureless, as they had expected, but contained very deep trenches and canyons and submerged mountain ranges higher than the Himalayas. These discoveries fed into the concept of plate tectonics and are thus crucial to our understanding of the Earth.

However, it was not until the realization that sound travels easily through water and the development of acoustics and the echosounder in the 1930s, followed by the advent of the multibeam sonar, that truly detailed maps of the seafloor could be constructed. These charts have proved vital for the advancement of the oil and gas industry, both for exploring offshore and for transporting hydrocarbons by ship and undersea pipelines.

Yet more than 85% of the world ocean floor remains unmapped by modern methods, according to the organization responsible for the task, the General Bathymetric Chart of the Oceans (GEBCO), a joint project of the International Hydrographic Organization and the Intergovernmental Oceanographic Commission of UNESCO.

GEBCO now plans a comprehensive mapping of the entire ocean floor. As part of this it will develop a new structure for the global coordination of mapping activities and the gathering of all available depth measurements into a database, encouraging businesses and organizations which routinely collect bathymetric data to contribute. As a major player in this area, the oil and gas industry should be encouraged to participate

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