More powerful earthquakes could rock the globe in 2018 because of infinitesimal changes in the speed of the Earth’s rotation, scientists warn.
It seems contradictory, but a minuscule slowing of the Earth’s rotation over years, which can extend the length of a day by a millisecond or more, appears to be linked to an increase in major quakes.
Roger Bilham of the University of Colorado and Rebecca Bendick of the University of Montana say that historical data since 1900 clearly reveal a “strong” link between major global earthquake activity and a slight slowing of the Earth’s rotation for five or six years. That has occurred approximately every 32 years. If that pattern continues, the number of powerful quakes in the coming year could triple, according to the researchers.
“On five occasions in the past century, a 25 [to] 30 percent increase in annual numbers of earthquakes [of a magnitude 7.0 or greater] has coincided with a slowing in the mean rotation velocity of the earth,” the scientists noted in a research abstract. They presented their findings recently at a meeting of the Geological Society of America.
“Next year we should see a significant increase in numbers of severe earthquakes,” Bilham warned in an interview with The Observer. “We have had it easy this year. So far we have only had about six severe earthquakes. We could easily have 20 a year starting in 2018.”
The researchers don’t understand precisely the dynamics that may explain what’s happening when the Earth slows. As the Earth’s rotation slows, the diameter of the equator shrinks, essentially “rumpling” the tectonic plates nearby and increasing the likelihood of a major earthquake where the plates connect, Bilham explained on the BBC radio program “Science in Action.”
Historically, most earthquake upticks linked to a slower planet rotation occurred near the equator in the West and East Indies, according to the scientists. Since 1900, more than 80 percent of all major quakes on the eastern Caribbean plate boundary, including the 2010 Haiti quake, have occurred five years following a “maximum deceleration” of the Earth’s rotation, according to Bilham and Bendick.