Earthquakes regularly rattle our planet, striking somewhere in the world every hour of every day. Such events are the result of the slow-motion march of tectonic plates that build stresses in Earth’s crust and upper mantle. Eventually the stress hits a breaking point and releases in a ground-shaking quake that can send blocks of the Earth careening out of place.

Most temblors are too small for humans to feel, but every so often a whopper will rock our planet. The majority of earthquakes occur near the boundaries of tectonic plates—like the mighty San Andreas fault that runs along the United State’s west coast—but scientists still can’t say precisely where and when the next big quake will strike. So