Deep Sea Minerals - Vol 2 - Manganese Nodules

4.1.1 Acoustic Survey The first phase of manganese-nodule acoustic surveying involves large-scale reconnaissance grid surveys with spacing of several tens of square kilometres. This is carried out using wide-swathmul- tibeam echo sounder systems to produce bathymetric maps of the region, whichpermit elimination of those areasnot suited tomining (such as seamounts, troughs, cliffs, steep or rugged terrain, etc.).

The second phase of acoustic surveying involves more de- tailed imagery within a prospective area, with the aim of pro- ducing a complete bathymetric map and a map of estimated nodule abundance. This typically involves using deep-towed sidescan sonar to generate high-resolution sea-floor images of the flat areas that are more favourable for mining. The deep- towed systems are also able to detect small-scale features and variations in nodule abundance.

Bathymetric map of pilot area showing the selected point about Mn’s abundance. Photo courtesy of KIOST.

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