More big earthquakes in 2018 as Earth slows slightly, theory suggests

Monday, 20 November 2017

More big earthquakes in 2018 as Earth slows slightly, theory suggests.

Two US scientists have come up with a theory that suggests a big increase in devastating earthquakes, particularly near the Equator, in 2018 following a tiny slowing in the Earth's rotation.

'The correlation between Earth's rotation and earthquake activity is strong and suggests there is going to be an increase in numbers of intense earthquakes next year,' Roger Bilham of the University of Colorado told The Observer.

Bilham and Rebecca Bendick of the University of Montana presented a paper on the link between seismic activity and the Earth's rotation speed at the annual meeting of the Geological Society of America.

A damaged building in Kermanshah, Iran after last week's magnitude 7.3 earthquake that killed hundreds of people.

The slowdown in Earth's rotation is tiny - a millisecond a day sometimes - which can be measured by atomic clocks.

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Bilham and Bendick found that periods when the number of intense earthquakes had increased followed periods of about five years when the Earth's rotation slowed slightly.

Earth's rotation began one of the periodic slowdowns more than four years ago.

'Next year we should see a significant increase in numbers of severe earthquakes,' Bilham said. '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 link between the Earth's rotation and the number of big earthquakes was unclear, but slight changes in the behaviour of the Earth's core could be causing both effects.

Most of the intense earthquakes that responded to changes in day length seemed to occur near the Equator, Bilham said.

Bilham and Bendick looked at earthquakes of magnitude 7 and greater since 1900, finding five periods when the number of big quakes increased significantly.

In those periods there were 25-30 intense quakes a year, compared to an average of about 15 at other times.