Research conducted by the University of Colorado Boulder suggests that there could be an increase in severe earthquakes due to Earth’s slower rotation.
Roger Bilham of the University of Colorado and Rebecca Bendick of the University of Montana conducted a study where they looked at earthquakes of magnitude 7.0 and greater that had occurred since 1900.
Both scientists found that in periods of slower rotation there were between 25 to 30 intense earthquakes a year, and that on average years, there were only about 15 major earthquakes happening annually since the year 1900.
The scientists cannot explain with certainty how slower rotations can lead to severe earthquakes yet. A possible explanation, Bilham suggests, is that when Earth’s spin slows down, the equator shrinks, meaning that the edges of the tectonic plates get squeezed. Although this amount of squeezing is not huge, it puts a bigger tension on plate boundaries that are already under stress
Bilham and Bendick found that there had been several periods of around five years over the past century and a half when Earth’s rotation slowed with this effect on the equator.
In other words, researchers searched for correlations between periods of intense seismic activity and other factors, and discovered that when Earth’s rotation decreases by even the smallest amount, the change was followed by periods of increased intense earthquakes. According to Bilham, even the slightest changes in Earth’s rotation are measured by atomic clocks, which happen every few milliseconds per day.
This slowdown of Earth’s rotation was observed in 2014, 2015, 2016 and now 2017. If 2018 is the fifth year of the slowdown, and if this pattern holds, then next year can be expected to have the most severe earthquakes. Severe earthquakes are defined to have magnitudes above 7.0. Scientists expect to see more than 20 severe earthquakes in the next year.
If this hypothesis is correct, the ability to predict earthquakes would be an advancement to the fields of geology and geophysics. In addition, knowing that earthquakes will be more constant in the next five years is useful to the city planning department when considering how to construct buildings that would be stronger and more safeguarded against these natural phenomena. In other words, knowing how many earthquakes are likely to happen in the future will make people act now, rather than later.
While scientists predict that more than 20 earthquakes will occur in 2018, they do not have exact information on where these earthquakes will occur.
There are many reasons to be skeptical. Even though Bilham and Bendick were able to find a correlation between Earth’s periodic slowdown and earthquakes, there is no evidence of a causal relationship. In addition, 2017 did not have 15 to 20 earthquakes as predicted; there were only seven earthquakes that were above 7.0 in magnitude. Even if the earth gets 20 to 30 earthquakes in the next year, this increase would not necessarily be caused by Earth’s slowing rotation.
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