Mapping the Ocean Floor
Map of Giggenbach volcano (using multibeam sonar)
Two main methods are used to map the shape and depth of the seafloor.
Satellite altimetry
- uses satellites to measures subtle but permanent differences in sea-surface height
- global coverage
- low resolution: 2-5 km
- vertical accuracy: 200-300 m
Multi-beam sonar
- uses multiple echo-soundings to map narrow (2-10 km) sections of the ocean floor
- collected using scientific ocean going vessels or AUV’s – which is more expensive
- limited coverage
- good resolution:25-100 m (0.5m for AUV’s)
- vertical accuracy: 1-2 m
Multi-beam sonar © NIWA.