More on Monster Waves

Hollywood fantasy? Tidal wave disaster is just waiting to happen Scientist says governments are ignoring threat of a piece of rock as big as the Isle of Man crashing into the Atlantic Ian Sample, science correspondentTuesday August 10, 2004The Guardian It has everything you could wish for in a cliche-ridden disaster movie. A beautiful volcanic island in the Atlantic is on the brink of catastrophic collapse, threatening to unleash giant waves that will wreak havoc around the globe within hours. And while scientists try in vain to make their concerns heard, the world's governments look the other way.

But yesterday a leading expert claimed the doom-laden scenario was not only real but was being almost completely ignored by people in power.
Bill McGuire, the director of the Benfield Grieg Hazard Research Centre at University College London, said a huge chunk of rock, roughly the size of the Isle of Man, was on the brink of breaking off the volcanic island of La Palma in the Canaries.

When - Professor McGuire says it is not a matter of if - the rock plunges into the ocean it will trigger giant waves called mega-tsunamis.
Travelling at speeds of up to 560mph, the huge walls of water will tear across the ocean and hit islands and continents, leaving a trail of destruction.
Mega-tsunami waves are much longer than the ones we are used to.
"When one of these comes in, it keeps on coming for 10 to 15 minutes," Prof McGuire said.
"It's like a huge wall of water that just keeps coming."

Computer models of the island's collapse show the first regions to be hit, with waves topping 100 metres (330ft), will be the neighbouring Canary Islands. Within a few hours the west coast of Africa will be battered with similar-sized waves.

Between nine and 12 hours after the island collapses, waves between 20 and 50 metres high will have crossed 4,000 miles of ocean to crash into the Caribbean islands and the eastern seaboard of the US and Canada.

The worst-hit will be harbours and estuaries, which will channel the waves inland. The loss of life and destruction to property will probably be immense, according to Prof McGuire.
Britain would not escape entirely, he added. Waves of around 10 metres are likely to strike the south coast four to five hours after the island collapses, causing damage to seaside resorts and ports.

Such devastating natural disasters are rare, occurring on average every 10,000 years. But La Palma could collapse much sooner than that. "The thing about La Palma is we know it's on the move now," Prof McGuire said.

The island came to the attention of scientists in 1949 when its volcano, Cumbre Vieja, erupted, causing a huge chunk of its western flank to drop four metres into the ocean. Scientists believe the chunk of land is still slipping slowly into the water, and say another eruption is likely to make the entire western flank collapse. "When it goes, it will likely collapse in around 90 seconds," Prof McGuire said.

Precarious
Despite the potential scale of the threat, little is being done to monitor the geological activity of La Palma. Only a few seismometers have been set up on the precarious western flank of the island, which do not provide enough information to predict when another eruption might occur.
"It's really a worrying situation," Prof McGuire said. "It will almost certainly go during an eruption. The problem is that with just a few seismometers on the island, we may not get the notice we need."

The scientist called for an international effort to install more sophisticated sensors on the island, as well as global positioning satellite units to detect how quickly the land mass was falling into the ocean. "We need to have better monitoring so we know when an eruption is about to happen," he said. Such a system could cost as little as a few hundred thousand dollars.

"The US government must be aware of the La Palma threat. They should certainly be worried, and so should the island states in the Caribbean that will really bear the brunt of a collapse.
"They're not taking it seriously. Governments change every four to five years and generally they're not interested in these things."

Even with new monitoring equipment in place, La Palma presents a difficult problem for those charged with mitigating against natural disasters.
Little can be done to protect against the waves produced when La Palma collapses. Barriers would not be able to sustain the battering, and breaking the island apart before it collapses is either too dangerous or time-consuming.

New sensors could warn of an impending eruption two weeks in advance. But no one knows whether the island will collapse during the next eruption, or in an eruption that will not happen for centuries.

Ordering mass evacuations would have a huge financial impact that could cause resentment if it turned out to be a false alarm. The disaster could affect up to 100 million people from the coast of Africa to the Canary islands and the east coast of North America.

"The future president of the US has got to make a call at some point, that when La Palma erupts, what is he going to do?" Prof McGuire said.

"Is he going to evacuate all the major cities on the east coast? If he gets it wrong, nobody's ever going to pay attention again and he'll be out of a job."