Thursday 26 April 2018

Can animals sense earthquakes before us?

Kate Banks of St Joseph's Presentation Convent, Lucan, Dublin

Professor Chris Bean

Nearly 16,000 people died as a result of the earthquake and subsequent tsunami in Japan in March 2011.

Over 316,000 Haitians died in the devastating earthquake of January 2010 and in December 2004, 230,000 people across 14 countries died as a result of the Indian Ocean tsunami.

Here in Ireland, all seems quiet. So, why are we living in such relative safely and why were these devastating events not predicted in other countries?

Plate tectonics is the answer. We live in one of the most tectonically stable areas of our planet, far from an active plate boundary.

In contrast, most of the world's largest earthquakes occur at plate boundaries. These are complex zones where highly stressed and mangled rock masses judder past each other relentlessly.

Earthquake prediction has proved elusive in the face of such complexity.

We do know approximately where the world's largest earthquakes will occur, but not when they will rupture or exactly how big they will be.

In countries with high levels of earthquake preparedness, such as the United States, New Zealand and Japan, this knowledge of approximately where big earthquakes will be located informs both building codes and educational practice in effective early response to natural disasters.

When these 'earthquake proof' building codes are properly adhered to during building construction, and when people are educated in how to respond to strong ground shaking or potential tsunamis, many lives have been saved.

This explains the difference in the death toll between Japan and Haiti.

So, the current research focus concentrates on questions relating to understanding how the ground will shake, what type of buildings will withstand the shock, where will the big aftershocks occur, will there be a tsunami and if so, how big will it be?

Yes, things can go very wrong, as in Japan in 2011, when the damage to the nuclear reactor compounded the disaster caused by the tsunami, but significant progress is being made.

As for prediction, despite the myths, animals do no better than us at predicting earthquakes -- basically they can't!

Some may be sensitive to the shaking of the ground, but only after the earthquake has occurred.

Back in Ireland we are not completely immune.

We do have earthquakes from time to time that people feel (like the magnitude 2.2 event in Donegal in January), but most are so small that they can only be detected on sensitive instruments called seismometers

Although a very large earthquake in Ireland is highly unlikely, very rare but significant tsunamis are a possibility -- most likely driven by either landslides at islands in the Atlantic (eg Canary Islands) or by underwater landslides on the continental shelf off our own West coast, like the eight metre tsunami generated by the Grand Banks slide off the coast of Newfoundland, in 1929.

Irish Independent Supplement

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