THE GEOLOGY OF SEA-FLOOR MASSIVE SULPHIDES
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If a sediment plume is created through dispersal by currents,
it will have a larger footprint than the physical mining area.
There is also the possibility of plumes extending upwards into
the water column, although engineering design should mini-
mize such movement. Similarly, the area affected by discharge
of the waste-water and fine materials could be more extensive
than the mined area. Sediment and water-column plumes will
disperse with distance, and this dilution will mean there is a
gradient of impact, with effects lessening with distance from
the mining site.
The potential extent of impacts
3.6
The Integrated Ocean Drilling Programme has conducted nu-
merous scientific investigations of hydrothermal sites around
the world. Pictured here is the Deep Sea Drilling Vessel JOIDES
Resolution. Photo courtesy of Elaine Baker.
In addition to potential impacts from normal operation, it
is important to consider accidental events and natural haz-
ards. These include such possible problems as spills and
oil leaks from the vessel/platform, which enter the sea,
and leaks from the riser pipe or from sea-floor equipment
(e.g., hydraulic oil leaks). Although unlikely, such extreme
events as a ship sinking or collisions between vessels or
with marine mammals are possible. Commercial operators
and national management agencies must reduce the risk of
these sorts of events and must be prepared to respond in
the event they do happen. Such precautions are generally
covered under national and/or international regulations
and are not detailed here. Natural hazards, such as ex-
treme weather events, volcanic activity, etc., will also need
to be considered in the management plans.
Accidental Events and Natural Hazards
