Haiti, 2010 (COLIN CROWLEY)
The earth doesn’t spin at a constant speed. Various things can affect its rotation. Activities in its mantle and core affect it, as can atmospheric changes and ocean patterns. We’re not talking about big fluctuations in speed, but since 2011, the earth has been turning just a bit slower than usual, by a few-thousandths of a seconds. This has made our equator a bit smaller, like the best diet plan ever that lets you get thinner while moving around less. Unfortunately, though, tectonic plates haven’t see an equivalent reduction in size, and that means they’re beginning to feel the squeeze. And that can mean more seismic events at the surface.
Geologists Roger Bilham and Rebecca Bendick went through the historical records for other slowdowns over the last 117 years and found an alarming correspondence between slowdowns and an increase in the number of major earthquakes. They presented their findings at a recent meeting of the Geological Society of America.
The geologists conclude that a slowing in the earth’s spin tends to precede increased seismic activity by 5-6 years, and thus the current deceleration may signal a higher number of major earthquakes for 2018, 2019, 2020, and 2021. These would be temblors of 7 or higher in magnitude. 2017 has so far experienced seven such quakes. Bilham and Bendick say we may see, on average, 20 of them in each of the four years.
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