You wouldn’t have felt it, but sometimes the Earth’s rotation slows down. Sure, the fluctuations are minute – maybe a millisecond here or there. But two geophysicists think there could be more destructive quakes next year because of the phenomenon. There is a silver lining: such small changes also might help us forecast earthquakes.
Scientists have charted minuscule changes in the length of a day on our planet for decades. Sometimes we gain a millisecond, sometimes we lose one. But it turns out these tiny changes could impact us in a big way. They could be involved in the release of large amounts of underground energy. Rebecca Bendick of the University of Montana and Roger Bilham of the University of Colorado, Boulder presented the idea in a research letter published by Geophysical Research Letters in late summer and at The Geological Society of America’s annual meeting last month.
Slowdowns in Earth’s rotation have corresponded with global increases of magnitude seven or greater earthquakes during the last century, according to the researchers: Bilham said, “The Earth offers us a five-years heads-up on future earthquakes.” In slowdown periods, Earth often sees two to five more large earthquakes than usual – but these arrive after the slowdown begins.
Earth’s magnetic field develops a temporary ripple as day length fluctuates over decades, according to Science Magazine. Both effects could be caused by small changes in molten iron’s flow in the outer core, researchers think. Earth spins 460 meters per second at the equator, according to Science Magazine, and “given this high velocity, it’s not absurd to think that a slight mismatch in speed between the solid crust and mantle and the liquid core could translate into a force somehow nudging quakes into synchrony.”
Bendick said the connection may seem crazy. But other researchers are intrigued – and geologist James Dolan of the University of Southern California said we should know if they’re on to something in five years. Based on the research, Earth should see five more major earthquakes than average starting in 2018 and we may have a new tool for earthquake forecasting.