Perhaps in many ways.

But two of them I will tell you as simply as I can, because they seem the most likely, and probably the most common.
Suppose, as the earthquake shock ran on, making the earth under the sea heave and fall in long earth-waves, the sea-bottom sank down.

Then the water on it would sink down too, and leave the shore dry; till the sea- bottom rose again, and hurled the water up again against the land.

This is one way of explaining it, and it may be true.

For certain it is, that earthquakes do move the bottom of the sea; and certain, too, that they move the water of the sea also, and with tremendous force.