Dean M. Chriss
Splash, Victoria, Australia
(Click image to enlarge)
Ocean waves carry lots of energy, even when they are
relatively small. This energy does not interact with the ocean floor when water depth is greater than
half the distance between wave crests, known as the wavelength. Under these
conditions the wavelength remains constant as the waves travel toward the shore.
As they get closer to shore the depth decreases, waves begin to interact with the ocean floor, the wavelength and
velocity decrease while the wave height (amplitude) increases.
When a small swell passes over an area where submerged rock platforms or other
large geological features cause a sudden decrease in the water's depth,
a small swell will increase dramatically in height.
Simplistically, all of that energy must go somewhere. It lifts the water,
which in these amounts is incredibly heavy.
As the tide changes, all or parts of the rock platforms
mentioned above can become level with the water's surface or exposed above
it. If the ocean facing side of the rock platform is vertical, or nearly so,
the water depth encountered by traveling waves decreases to zero in a fraction of a second.
As before, all of that
energy must go somewhere, but now it must do so
The large 10.5 meter (34 foot) wide rock this photograph is higher
part of a much wider volcanic rock platform that
is still submerged. Large waves appear as if by magic along the submerged
edge on either side of the exposed rock. Wave segments that encounter the
rock essentially explode, releasing a huge amount of energy in a very short