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Westcountry's tsunami could lead to quake prediction

By Western Morning News  |  Posted: July 02, 2011

  • The mini tsunami, resembling a bore-like wave, travels up the River Yealm in south Devon

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The hair-raising truth about the mini tsunami triggered by an under-sea event, by Michael Hanlon.

This week, parts of the Westcountry coastline were hit by what appears to have been a mini tsunami. The wave was of no great height, but it was still substantial enough to suck the sea out for 150 feet or more, before surging back in to drench the causeway linking St Michael's Mount to the mainland, and giving tourists a soaking.

The wave rolled up the estuaries and rivers from Mounts Bay in the west to Plymouth in the east, sending small boats rolling on their keels.

If that isn't strange enough, witnesses said it was preceded by a surge of static electricity. "People's hair stood on end," said a National Trust guide on the Mount.

Others reported the air going unnaturally still, with a dense, warm clamminess settling over land and sea before the wave struck.

Of course, the Cornish tsunami on Monday was tiny compared to the one that devastated Japan earlier this year. But the reports raise a tantalising question: might we have found one of the great holy grails of seismology — a reliable way of predicting earthquakes which could save thousands of lives?

Experts suggest that the Cornish tsunami was caused by either a small earthquake or an undersea landslide off the Irish coast 250 miles away.

One theory is that the resulting rock vibrations could generate a powerful electrical charge, strong enough to travel all the way along the seabed to land, up the beach, and reach the top of a tourist's head.

"It's called the piezoelectric effect," says Chris Shepherd of the Institute of Physics, explaining that quartz crystals, present in the ancient rocks in and around Cornwall, could generate a high voltage if squeezed. "It's the same effect used in gas lighters on your cooker."

Intriguingly, something similar but far more dramatic seems to have taken place several days before the Japanese earthquake.

After studying data sent by satellites over the Pacific Ocean, NASA scientists at the Goddard Space Flight Centre in Maryland have discovered that there was a sudden and dramatic pulse of heat high in the atmosphere over the epicentre of the quake 72 hours before it struck.

The heat pulse was associated with an equally dramatic increase in electrical charge in the air. Similar effects were reported, retrospectively, before the Haiti earthquake in 2007.

Just what was happening is something of a mystery. A persistent conspiracy theory doing the rounds on the Internet links recent big earthquakes and secret radio experiments allegedly being carried out by the Pentagon.

Far more likely, however, is a little-understood phenomenon called the "Lithosphere-Atmosphere-Ionosphere Coupling mechanism".

The theory is that in the days before an earthquake, the great stresses that have built up cause the release of large amounts of radioactive radon gas from deep in the Earth.

The radioactivity from this gas ionises the air on a large scale, electrifying it and heating it up. So could something like this, on a smaller scale, have explained the weird phenomena seen across Cornwall and Devon this week?

Perhaps what we saw was a combination of the piezoelectric effect and the release of radon gas — large quantities of which are present in Cornish rocks.

It is still very much a mystery. Dr Simon Boxall, an oceanographer who was out at sea on a small boat off the coast of Falmouth when the tsunami struck, thinks the wave had nothing to do with an earthquake at all, but instead was something called a "seiche".

"I'm 99 per cent certain," he said, pointing out that seismographs of the British Geological Survey did not seem to have detected any earth-shaking at all before the wave struck.

A seiche is a freak wave which can be caused by an area of very low or high pressure crossing an area of water.

If the speed at which the weather system is moving is just right, the sea underneath can "resonate" like a wine glass ringing when you rub the rim in the right way, and a single big wave can come seemingly from nowhere.

"The static had nothing directly to do with the wave, but it did have a lot to do with the low-pressure system," Dr Boxall insisted, adding that southern England was hit by a number of powerful thunderstorms later that day.

"The air would have been charged with static."

Whatever the explanation, we may be getting tantalisingly close to finding a way to predict earthquakes — something dismissed as a pseudoscience until very recently.

For centuries there have been reports of lightning, static and even fireballs in the sky associated with earthquakes together with, of course, persistent reports that animals are able to sense that something is about to happen and flee to higher ground.

These reports are now being taken more seriously.

More than a third of a million people perished in the Indian Ocean tsunami on Boxing Day in 2004 and 25,000 more in Japan this year.

If satellites — or even the hairs on the back of your neck — could be used to predict disasters like these hours or even days ahead, millions of lives could be saved in years to come.

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