The Earth is a constantly moving, vibrating mass. As it oscillates back and forth, stress builds up in the surface layers of the planet. Eventually, something snaps, and the crust ruptures. That is how an earthquake works: the sudden movement of the Earth’s crust releases stored elastic energy in the form of seismic waves (vibrations) that propagate through rock until they reach an undefended spot and cause a quake.
Of course, it’s more complex than that. For starters, most people think of earthquakes as one-off events. But what if we told you that earthquakes happen all the time? There are over 25 million earthquakes worldwide each year, with magnitudes ranging from tiny quakes that barely register to people on the ground. They continue to occur because the Earth is still moving beneath our feet.
There are always cracks in our planet’s crust waiting to be filled with tension again. Here we go, even though researchers have only recently begun to understand why and how this occurs.