Magnitude 8.2 earthquake off Chile increased risk nearby

Damage following the tsunami from the April 2014 earthquake.

Juan González-Carrasco (Universidad Catolica del Norte, Chile)

Sometimes it seems like the Internet holds as many ridiculous claims about predicting earthquakes as it does cat memes. While it’s very clear that neither seismologists nor anyone else can fully predict earthquakes, that doesn’t mean the scientists know nothing.

The basic process behind an earthquake is pretty simple. Friction between two blocks of rock trying to slide past each other along a fault holds them in place until the sliding force is too great, and then BOOM!—an earthquake. We can measure that sliding very precisely, so as the strain on the fault mounts, we know an earthquake will happen; it’s just a question of when. And the greater the strain that has accumulated since the last earthquake, the larger the potential magnitude of the next one.

Along a long subduction zone, where an oceanic plate slides beneath a continental plate, faults slip one section at a time. Sections that haven’t slipped in a while but sit between sites of recent major earthquakes are known as “seismic gaps.” Those sections are likely to host the next major earthquake in the region.