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Cloudy with a Chance of Earthquakes

Credit: Petrovich12/Adobe

Credit: Petrovich12/Adobe

By Simon Lamb

The rupture of a megafault beneath New Zealand in 2016 has revealed a periodicity to earthquakes that may enable geologists to forecast seismic events based on satellite monitoring of the Earth’s movements.

The full text of this article can be purchased from Informit.

Living in New Zealand, I have felt many earthquakes. Even though I am a geophysicist who studies their causes and effects, I still experience deep uneasiness whenever they occur. The idea of a solid and fixed bedrock to our world is deeply embedded in the human psyche, so it’s truly terrifying when this fundamental assumption is turned on its head during an earthquake.

During the few seconds of an earthquake – stretching sometimes to minutes in a big one – the bedrock is flung up and down, with accelerations that can be greater than those experienced by a rugby ball when it’s dropped or kicked. However, once the earthquake and aftermath of numerous aftershocks have receded into the past, the ground seems fixed and solid again and we quickly revert to our old assumptions of bedrock stability.

So why do certain parts of the Earth switch between long periods of stability and short bursts of violent seismic shaking? I think the answer to this question is central to finding new ways to forecast earthquakes in the future. The key to this is understanding what happens between big earthquakes.

Since satellite-based monitoring of the Earth’s surface enabled precise surveys of the landscape, it has been clear that the solid Earth is not fixed at all, but is instead in constant motion. The movements are very slow – not more than a few centimetres per year – so...

The full text of this article can be purchased from Informit.