Tsunami Warning Part 2

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Miniscule chance of a bloody big wave

As noted in yesterday's post, we have a seismic fault on the Grand Banks capable of triggering significant earthquakes of at least 7.2 on the Richter scale. There is the possibility however slight of another earthquake and suboceanic landslide, which could trigger a major tsunami like the one that hit our shores in 1929.

But there has been even greater concern and controversy in scientific circles in recent years about a volcano known as Cumbre Vieja on the island of La Palma, in the Canary Islands. A scientific paper by Ward and Day is devoted exclusively to exploring this scenario. It warns of a potentially cataclysmic landslide at La Palma.

The entire Canary Islands, formed by volcanic action, rise steeply from water that is more than four km deep. The Cumbre Vieja has a volcanic ridge that rises 2,000 metres from sea level. Ward and Day claim it has an unstable flank that could collapse, triggered by volcanic eruption, sending 500 cubic km of mountain straight to the bottom, at a speed of 100 metres per second. That's a lot of rock, if you think about it.

The scientists' computer modeling suggests that this disturbance would, at its source, generate a dome of water 900 metres high. It would hit the Canary Islands within minutes, and, well, no more Canary Islands (as we know it). From there, it levels out as it radiates in a wide arc across the Atlantic Ocean, coming ashore in parts of Africa with 50 to 100 metre waves. Sheer devastation.

Spain and England would get off lucky, with waves five to seven metres high, the brunt of the wave broken by La Palma island itself.

The wave would travel across the Atlantic basin, coming ashore first in Newfoundland, with an estimated height of 10 metres (Labrador would apparently be sheltered from the worst of the waves). The eastern shores of North and South America would be pummeled by waves 20 to 25 metres high, with catastrophic, almost incomprehensible results.

That's the worst case scenario, as dramatized in this (somewhat sensationalized) BBC documentary that you can also watch on YouTube.

However, the Tsunami Society of America and others have examined the Ward & Day theory and said the threat of disaster is either seriously exaggerated or pretty much non-existent.

Their view is that the mountain will disintegrate gradually, over a short period of time, rather than all at once. But they can't assure us, with certainty, that there is no threat at all. A catastrophic incident could happen anytime in the next 10,000 years or so.

In disaster movies, of course, the naysayers are always proven wrong and are the first to be killed by the giant mutant fruit flies. Real life, of course, is something different.

And I do hope the naysayers are correct.

In the meantime, do you know what to do in the event of an approaching tsunami (assuming you get some warning)? Naturally, you get to the highest ground possible, as quickly as you can.

And if you should see the water in the bay suddenly pull back, exposing the ocean floor, grab your loved ones and get out of there. When the water comes back, it will be a tsunami and it will not be pleasant. (During the 2004 tsunami, a little girl recognized this phenomenon from her school lessons, warned everyone on the beach to run, and saved a few lives.)

There is some information online about the seismic fault off Newfoundland, but most of it is focused on the tidal wave of 29. I could find no specific research about when we might expect our next seismic disturbance, probably because none exists.

And a search for Newfoundland fault' yields a solitary blogger who says, no, it's all Ottawa's fault.

But seriously, if they haven't already, our emergency measures people should begin developing a tsunami warning and reaction plan.

The chances of it happening may be miniscule, but if we ever do see a tsunami, the implications for our coastal cities and towns would be enormous.

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