Hidden seascapes
Although invisible to us, the landscape below the sea surface is just as varied and spectacular as onshore. Mountain chains, gorges, abyssal plains and continental shelves constitute a variety of landscapes and marine biotopes, and, accordingly, a range of resources. In parts of Europe, the rocks beneath sea level are the source for oil and gas, but also possible locations for carbon dioxide sequestration to address global warming. Fishing and fish farming are significant offshore industries. Fish and other types of marine life depend on suitable spawning and breeding grounds; consequently the seabed conditions are key factors in marine habitats. Furthermore we exploit the seabed for sand and gravel, excavate it for pipelines and cables, and are now developing offshore wind, wawe and tidal power. But how much do we understand about the long-term effects of these activities on sediment transport and marine habitats?
Coastal zone management and marine hazards
The marine environment is also dramatically dynamic, nowhere more so than in the coastal zone. The coastal zone has been subject to large building and leisure business development. The dynamic environment may cause geohazards. The large tsunami accident in 2004 reminds us that seismic events on the seafloor can have devastating impact on shore. Also, submarine landslides can either propagate onshore or generate tsunamis with catastrophic results. Coastal erosion and seawater intrusion in groundwater are other issues to be addressed. Coastal zone is also abundant in diverse landscapes - from sandy and pebbly beaches to high, rocky cliffs. Many coastal areas are protected as the unique geoheritage and geodiversity sites.
Probing the secrets of the seafloor
In order to manage our seabed activities and assess geohazard risks, we need a proper knowledge of the nature and form of the submarine domain. However, compared with the land surface, our understanding of the submarine environment is limited. As a matter of fact, we know more about the surface on the planet of Mars than we do about some European submarine areas. With new surveying techniques, however, the secrets of the seafloor can be revealed. A better understanding of the marine landscape can result in more detailed maps and a better understanding of the processes active in the marine environment.
Examples from the Surveys:
Norway:
The Oslofjord area has the highest population density in Norway, and a lot of activities take place in the coastal zone. The Geological Survey of Norway has carried out detailed seabed mapping of the fjord. The data can be used to identify possible environmental hazards, old shipwrecks and neotectonic movements. The results were highly debated when the local governments decided to dump contaminated bottom sediments from the Harbour of Oslo, in a deepwater trench close to a fault zone in the fjord. The sludge is now being dumped beyond the margins of he fault zone.
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