Near the shore, the ground causes the bottom of the wave to
slow down, which makes the top curl over and break.
Waves bob up and down across the ocean, conveying kinetic (moving) energy from wave to
wave--until some force slows the waves down and causes them to break.
And shallow water causes an incoming wave to
rise, "trip," and break; waves don't break in deep water.
We are now close enough to the shock wave to
see the bones and sinews of it," Hester says.
Photo: Earthquakes can often be distinguished from explosions by comparing the magnitude of one surface wave to
that of a body wave (which travels deep in the earth) generated by an event.