Imagine it's 1500 years ago. There's a rumble beneath your feet, and the world begins to tremble. Stones crash down the slope, water sloshes out of containers, your hut collapses around you. What's going on?
You and I know quite a bit about what's going on: plate tectonics provides us with the explanation. But what did ancient people believe?
Imagine that the earth is held up by four elephants, that the elephants are balanced on a turtle, and that the turtle is balanced on a cobra. With this precarious arrangement, it's no wonder there's an occasional tremor. Or what if your island were held up by a giant catfish? Surely he'd manage to wriggle from time to time, causing earthquakes.
Gods battling, baby gods in the womb kicking, gods getting angry, gods stomping, gods suffering flatulence: all were posited by various cultures as the cause of earthquakes.
It was not until the Lisbon quake of 1755 that early scientists noticed there was an epicenter to quakes--but they still guessed wrong about the cause. And not until the 20th century did scientists begin to suspect there was a hot core to the earth and a mantle that might have something to do with earthquakes.
In 1910, Harry Fielding Reid came up with the "elastic rebound" theory of quakes, and that began the modern era.