standardization of environmental data and information - International ...

evaluated. The multibeam system had a side-scan sonar capability,
enabling it to record both bathymetric and side-scan information as the ship
travelled along at 12-13 knots. However, the side-scan instrument on the
multibeam was inferior to standard side-scan sonar. KORDI also had a
precise depth-measurement device that fed into the data-management
system in real time. Finally, there was a sub-bottom profile system, which
did a frequency sweep from 3-9 kilohertz and provided a good subsurface
image of the upper 100-200 m. It used the SEG-Y format -- a standard
format, with many variations, for seismic and time-series signal information.
As this bathymetric information was recorded in real time, a trained
graduate student was in charge of selecting and compiling data, and
removing erroneous data, manually, ping by ping. The information was then
compiled into a bathymetric map of the area traversed.
Dr. Lee said that that when he had arrived at KORDI after working
mostly in the tectonic plate margin environment, he had wrongly regarded
the manganese nodule area as the most boring place in the world, where
nothing was happening. He had not imagined how complex it was, how
many geologic faults and different types of abyssal volcanic plains existed in
the area.
To obtain a better side-scan sonar image of the entire survey area,
KORDI had contracted with the University of Hawaii to rent its MR-1 sidescan
sonar system. This was a big, surface-towed device much like the
GLORIA system but with much higher resolution, although with lesser
coverage. Within a month last year, KORDI had covered more than
100,000 km 2 of the CCFZ. Reviewing the results, he had been surprised to
find abyssal hills and hill-like structures, linear faults, flat areas and a sort
of volcanic outflow area, with many small volcanoes. Based on that
information alone, he thought he knew which areas to relinquish. The
undersea terrain would be a nightmare for a crawler or collector, which
would be unable to cross some of the steep hills.
KORDI also had a deep-tow side-scan sonar system that operated at
full ocean depth, which meant that it could descend to 6000 m and fly
about 100 or 200 m above the seafloor. From there it could image 2-4 km
swaths in real time, transmit the data to the ship, and also provide a
bathymetry profile and a more accurate sub-bottom profile than could be
done from the ship 5 km above.
INTERNATIONAL SEABED AUTHORITY 259