Boston, New York and Miami were hit by 50-meter tidal waves in quick succession, starting at around 01:30 this morning.

It is believed that a minor volcanic eruption at La Palma in the Canary Islands caused a massive collapse of unstable volcanic slabs, twice the volume of the Isle of Man, resulting in monster waves – the biggest yet recorded.

Exactly ten years after the first warnings of a mega-tsunami emerged in academic circles, emergency services have been stretched to breaking point as the effects became clear this morning. It is thought that the US death toll could reach a million. The total cost of damage could reach a trillion dollars.

The elevated roads inland from Miami South Beach seem to have been lifted off their supports. The effect in low-lying areas has been devastating. Electricity and water supplies have been cut completely.

Brazil, the west coast of north Africa and the English south coast have also suffered extensive damage. The BBC estimates that two million people could have been left homeless in these regions.

Facts are limited at this stage. The only communications still operational are the cities’ broadband wireless networks. These are providing the backbone for emergency services as they try to cope with the massive loss of life and the suffering of the multitude of injured citizens and visitors.

News organizations are scrambling to get teams onto the ground.

ANALYSIS >> SYNTHESIS: How this scenario came to be

Background

That story about the Canarian mega-tsunami engulfing the US eastern seaboard has been doing the rounds for several years.

The Benfield Hazard Research Center, the British research unit responsible for the 2001 report claiming that a mega-tsunami might be triggered by the eruption of the Cumbre Vieja volcano on La Palma in the Canaries, teamed up with scientists from the University of California in 2004.

The researchers claim that the western flank of the Cumbre Vieja volcano might cave in after an eruption, sending a huge mass of rock, twice the size of the Isle of Man, crashing into the sea and unleashing an immense tsunami which would fan out across the Atlantic at speeds of up to 800 km. After 10 minutes, the wall of water would have moved almost 250 kilometers. The other Canaries and the West Saharan shore would be worse affected with waves of 100 meters from crest to trough. Florida and the Caribbean would be hit by waves of 50 meters some 8 to 9 hours after the landslide. Brazil would be hit by waves as high as 40 meters. The Atlantic coasts of Spain, Portugal, France and Britain, would also be affected by waves as high as 10 meters. Damage would clearly be in trillions, though its true extent is unsure as this would greatly depend on the ‘inundation distance’ – the distance the waves penetrate inland. The group expects this to happen sometime in the next few thousand years.

The Guardian newspaper reported the event in jocular sensational mode (“Mega-tsunami to devastate US cities“), quoting the leader of the team, Prof McGuire who was clearly out there with his begging bowl.

“It’s really a worrying situation. 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 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.”

Dr Simon Day from the Center’s website was somewhat calmer though no less alarmist. “Anyone planning a holiday to the Canary Islands and the islanders themselves need not panic. Cumbre Vieja is not erupting right now so the short-term and medium-term risks are negligible.

“Eruptions of Cumbre Vieja occur at intervals of decades to a century or so and there may be a number of eruptions before its collapse. Although the year-to-year probability of a collapse is therefore low, the resulting tsunami would be a major disaster with indirect effects around the world. Cumbre Vieja needs to be monitored closely for any signs of impending volcanic activity and for the deformation that would precede collapse.”

When the original research was published in 2001, the Spanish press and scientists were heavily critical of the way it was reported. El País noted that the research group was entirely funded by an insurance company.

The Spanish vulcanist Juan Carlos Carracedo was first to spot the instability caused by the 1949 cracking. He was horrified by the sensationalism of the British researchers, stating: “The error is modeling a phenomenon when there are no (sic) probabilities of it happening. It is as if one makes a model of what Madrid would look like after an atom bomb explosion. What interest does it have for the general population when the probability is not determined? We are talking about a geological timescale!”

Carracedo and the Spanish press have been silent so far on the 2004 research announcement.

The last time La Cumbre Vieja erupted and caused slippage was in 1949. A huge block of its western flank dropped four meters into the sea. Some scientists believe the chunk of land is continuing to slip into the sea, making the flank unstable and liable to collapse in the event of further eruptions.

A Mega-tsunami is one of those rare and huge events of severe global impact which scientists jocularly refer to as ‘gee-gees’, Global Geophysical events. Other gee-gees that scientists attempt to predict (or bet on) are climate change, super-eruptions and asteroid and comet strikes.

The immediate risk of a tsunami to devastate America’s east coast may be overstated in the short term. But a fairly minor quake could trigger that scenario. What if it does? What could be the implications? Let’s hear some scenarios from you!