The sea floor is not flat! Just like on land, there are steeper and flatter places. There are mountains and valleys and features of different shapes and sizes. The shapes of the sea floor are similar to those on land, but it's easy to see that some shapes are unique to the sea floor.

What does this have to do with underwater slides that generate tsunami? Even under water, areas with steeper slopes tend to be more unstable and prone to slides.

Maps of sea floor bathymetry show where the gound is steepest and more likely to slide.

Steep areas are more likely to collapse if sediments are already piled up too high, and if earthquakes give the ground a good shake. Are there steep slide-prone areas close to shore in southern California?

Whether tsunami will be generated is another matter...

Very detailed maps of the sea floor, like those created using side-scan sonar methods, may actually show the shapes of slides. Images like the one to the left shows collapsed ground and the scars left behind.

Ways to measure bathymetry
Information about these methods coming soon:

• Sonar - using sound waves to measure distance


• Multibeam - a kind of sonar


• Satellite altimetry - an entirely different approach

At the Ocean Institute
Students and visitors to the Ocean Institute can view our 3-D model of the sea floor off southern California.

Words:
In reference to the surface relief of the Earth, we use the term elevation in referring to the height of land, and the twin term bathymetry in referring to the depth of the sea floor. Elevation units are usually given in feet or meters above sea level. Units of bathymetry are usually given in fathoms or meters below sea level.

What's the meaning of the word slope?