Roger Bilham, of the University of Colorado in Boulder, and Rebecca Bendick, of the University of Montana in Missoula, presented their findings, published earlier this year, at the annual meeting of the Geological Society of America in October.
Their contention is that miniscule variations in rotation, that will change the length of a day by approximately one millisecond, could create massive shifts in energy beneath the planet’s surface. The theory goes that the slowdown creates a shift in the shape of the Earth’s solid iron and nickel “inner core” which, in turn, impacts the liquid outer core on which the tectonic plates that form the Earth’s crust rest.
The impact is greater on the tectonic plates near some of the Earth’s most populous regions along the Equator, home to about a billion people.
“The correlation between the Earth’s rotation and earthquake activity is strong and suggests there is going to be an increase in numbers of intense earthquakes next year,”Bilham told The Guardian. “Major earthquakes have been well recorded for more than a century and that gives us a good record to study.”
Their study looked at all earthquakes registering 7 and up on the Richter scale since the turn of the 20th century. In this timeframe, the researchers discovered five periods of significantly greater seismic activity occurring approximately every 32 years. The last slowdown began four years ago.