Tag Archives: ocean floor

The Secrets of the Ocean Floor

Echo-sounding illustration. image from wikipedia

Three billion dollars sounds a lot to spend on a map. But if it is a map of two-thirds of Earth’s surface, then the cost per square kilometre, about $8.30, is not, perhaps, too bad. And making such a map at such a cost is just what an organisation called the General Bathymetric Chart of the Oceans (GEBCO) is proposing to do. GEBCO, based in Monaco, has been around since 1903. Its remit, as its name suggests, is to chart the seabed completely. Until now, it has managed less than a fifth of that task in detail. But means of mapping the depths have improved by leaps and bounds over recent decades. So, with the aid of the Nippon Foundation, a large, Japanese philanthropic outfit, GEBCO now proposes to do the job properly. It plans to complete its mission by 2030….

Despite water’s apparent transparency, the sea absorbs light so well that anywhere below 200 metres is in pitch darkness. Radio waves (and thus radar) are similarly absorbed. Sound waves do not suffer from this problem, which is why sonar works for things like hunting submarines. But you cannot make sonic maps from a satellite. For that, you have to use the old-fashioned method of pinging sonar from a ship. Which is just what GEBCO plans to do.,,,

[The technique used to map the sea floor] is “echo sounding”, using sonar reflected from the seabed. Marie Tharp and Bruce Heezen of Columbia University, in New York, pioneered the technique in the 1950s and 1960s by using technology developed during the second world war. With it, they mapped part of the Mid Atlantic Ridge, an underwater mountain chain…

Cable-laying companies, oil firms, academic oceanography laboratories, national hydrographic surveys and the world’s navies all have oodles of sounding data. One of GEBCO’s jobs is to gather this existing information together and sew it into a new database, to create a coherent portrayal of the known ocean floor.  The organisation is also keen to include data collected by helpful volunteers. A new digital platform overseen by America’s National Oceanic and Atmospheric Administration encourages the crowdsourcing of bathymetric data, letting mariners upload their findings easily. Recent political initiatives, such as a deal made in Galway in 2013 between America, Canada and the European Union to support transatlantic floor-mapping, will also boost efforts. National icebreakers are gathering information in parts of the ocean too frozen for other vessels to reach. And GEBCO is trying to persuade governments and companies with proprietary data on the sea floor to share them. One such firm, a cable-laying outfit called Quintillion, has already agreed to do so…

[A] accurate map of the seabed may help open this unknown two-thirds of Earth’s surface to economic activity. ..[T]he world’s navies (or, at least, those among them with submarine capability) will also take an interest—for an accurate seabed map will both show good places for their boats to hide and suggest where their rivals’ vessels might be secreted. Whether they will welcome GEBCO making this information public is a different question

Excerpt from Bathymetry: In an octopus’s garden, Economist,  Oct. 29, 2016

Fukushima Waste Disposal under the Ocean Floor

flatfish on ocean floor

The industry ministry will consider the feasibility of burying high-level radioactive waste from nuclear power plants under the seabed, which a working panel said Dec. 11, 2015 could be a “highly appropriate” solution.  In an interim report on disposal methods of highly contaminated materials from spent nuclear fuel, the panel said such waste could be disposed of in adjacent waters within 20 kilometers of the coastline.

It called the disposal method relatively realistic because the circulation of groundwater at sea is not as strong as on land. The panel said the site should be created in adjacent waters so that nuclear waste can easily be transported by ships.  The panel included the under-the-seabed disposal plan in nearby waters as a viable option for the final disposal site.

Based on this proposal, the ministry will set up an expert panel in January 2016 to discuss what specific technical challenges lay ahead.  The expert panel will discuss locations of active faults under the seabed and the impact of sea level changes to evaluate the feasibility of the project. It is expected to issue its recommendations by next summer.

While the government has encouraged municipalities to submit candidate sites for nuclear waste disposal, it is being forced to rethink this policy because no local government has come forward to provide a realistic disposal site.  Instead, it will hand-pick the “candidate sites from scientific perspectives” and unilaterally request local governments to comply with its research and inspection efforts.

Japan to consider ocean disposal of nuclear waste, THE ASAHI SHIMBUN, Dec. 12, 2015