In October, 2001, one month after 9/11, President Bush was informed by the CIA that, per an apparently reliable source, Al Qaeda had secreted a 10 kiloton nuclear bomb (almost as large as the one we dropped on Hiroshima) into New York City. Its exact location was unknown, and there was little chance it could be found before it might be set off. Bush asked his security advisors if this report were plausible, if Al Qaeda had the means to make or obtain such a weapon and get it into NYC undetected. He was informed that, unfortunately, they probably had that capability. The president told his people to do all they could to locate the device but not to inform the public or even Mayor Giuliani, apparently fearing a panic and perhaps a financial reaction on Wall Street. He was told that were the device to detonate there could be over a million casualties and the economic consequences to our country would make 9/11 seem like child's play.
Fortunately, as it turned out, the initial report was a false alarm. Yet there is another threat to New York, Washington, D.C., and the other U.S. Atlantic coast cities which could be more destructive than an atomic explosion in The Big Apple.
Its like has not been seen since the dawn of human history, about 4000 years ago. At that time most communities and agricultural areas likely were located on or near the coasts. The unexpected scale and devastation of earlier such "mega-tsunamis" may have been the bases for the almost universal accounts, in multiple ancient cultures, of a great flood that swept over the known world.
Many think the new super-tsunami, when it comes, will have its origin in the summit of the Cumbre Viejo volcano, on the southern half of La Palma, one of the Canary Islands, off North Africa. The volcano is not stable. At some point an eruption is expected to send its western portion, half a trillion tons of material at once, in a colossal earth and rock "avalanche" to the sea, creating an over 2000 foot high wave hurtling west at about 450 miles per hour.
It would hit Boston first, next New York, and the impacts would continue in quick succession on down the entire U.S. seacoast, finally destroying Miami and then the Caribbean region.
Europe would also not be unscathed. The invading sea from this one catastrophe could put much of western Britain under water.
The good news, however, is that Cumbre Viejo, though unstable, is not considered close to major volcanic activity now and that it may take several eruptions before a "mega-tsunami" is triggered. It is possible that the landslides might occur more gradually, in a series of smaller shifts of material that would each be much less destructive.
Further, once scientists detect evidence of fresh Cumbre Viejo volcanism, leading perhaps to another eruption, they and government officials would have time to warn people who then could leave coastal cities until the greatest danger would pass.
Finally, some geologists think the hazard may not be as great as is the consensus view. The geological record, though, does confirm several volcano spawned super-tsunamis of the predicted proportions having occurred in the past.
The odds of dying from a mammoth tsunami are much smaller than for being killed in a car crash. Events of this magnitude happily do not occur often. The one forecast to begin in the Canary Islands may not occur in our lifetimes. It could even be delayed until after the current millennium. But a civilization that intends to be around more than a few hundred years probably should begin to take such phenomena into account in its long-term planning. Otherwise, when the next super-tsunami does come, it could be more transforming of the world order than the sum of all the wars to date.
BBC Science and Nature, 5/24/03, "Mega-tsunami: Wave of Destruction;"
Fresh Air - NPR, 8/10/04, Dave Davies' interview with Graham Allison on "Preventing Nuclear Catastrophe;"
It's Happening, 8/11/04, "Nuclear Terrorism Threat."