Two geologists may have spotted a surprisingly simple correlation that can help predict earthquakes—and if they're correct, the Earth is on track for an uptick in major quakes next year. The pair pored over a century's worth of a data on earthquakes and detected a pattern: When the Earth's rotation slows, as it does periodically, the slowdown is followed by an increase in quakes with a magnitude of 7 or greater, reports the Guardian. Their research, published in Geophysical Research Letters, has been well-received in the field, and it will be put to the test soon. The rotational slowdowns typically happen over five years, and the last began four years ago. Meaning, we can expect to see two to five more major earthquakes than normal in 2018, or 17 to 20, reports Science.
"The Earth offers us a five-years' heads up on future earthquakes, which is remarkable," says Roger Bilham of the University of Colorado, who detected the correlation with Rebecca Bendick of the University of Montana. Exactly where the quakes will take place is fuzzier, but typically the increase shows up in regions along the Equator. The researchers aren't sure how to explain all this, but one theory is that it involves nearly imperceptible changes in the flow of molten iron in the Earth's core. That might be enough to slow down the Earth's spin a millisecond or two, a difference that can be measured by atomic clocks, and perhaps result in the release of vast amounts of energy underground. The cycle seems to take place about every three decades, writes geologist Trevor Nace at Forbes. (LA residents won't like this San Andreas prediction.)