An easy chance to save 40 million or so lives along North America’s East Coast, and similarly elsewhere around the world
by Win Wenger, Ph.D.
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Photo courtesy of Elan Sun Star
Six inches of rushing water can sweep away a car, which is why the weather people keep on pleading with their audience not to drive through where water is crossing the road.
Now envisage a hundred-foot-high wall of water advancing on Manhattan, or on any other coastal settlement along North America’s east coast. Where is that water coming from? Turn your (mental) camera to the westward, seaward slope of Cumbre Vieja Volcano, on Palma Island of Spain’s Canary Islands a few miles from Africa. You don’t have to look too closely in order to see the gigantic crack which has that entire massive slope “hanging by a thread” ready to plunge down into the Atlantic Ocean. The question is not whether, but when.
We might have another ten years, or the tsunami from that enormous landslide could be rushing toward us at this very moment.
It isn’t as if we didn’t have plenty of warning on this one in the scientific literature, to the point where National Geographic ran a televised special documentary recently on the situation while geologists corroborated each other’s findings and argued over their guesses. Nature warned us, too: the Indonesian tsunami, Japan’s tsunami, and for good measure the sideways eruption of Mount St. Helens when its southeastern slope collapsed the way Cumbre Vieja’s slope appears to be going. The West Coast tsunami a few years ago was the result of a landslide triggered by the Alaskan super-quake. A little longer ago, most of the people who died in the explosive eruption at Krakatoa died in that volcano-caused tsunami. And several thousand years ago, the eruption at Santorini wiped out a number of promising young civilizations all along the Mediterranean shorelines, possibly the origin of Plato’s Atlantis myth.
A similar situation exists on our West Coast. Several of the Hawaiian Islands have a history of splitting in half and surging a massive landslide onto the Pacific floor about every 200,000 years—overdue now by about 50,000 years, poised to hurl an even larger tsunami against our entire West Coast and, indeed, against every country bordering on the Pacific Ocean.
We don’t have to evacuate the areas threatened, even though levees cannot possibly stop tsunamis on this scale. There is an easy way to stop them, however. Take your cue from Mt. St. Helens on this one. Why didn’t that mighty slide-collapse and subsequent mighty blast launch a tsunami? Because the slide didn’t displace massive volumes of sea water that would have become those tsunamis. The slide didn’t go into the sea, but onto land, and didn’t get to displace any significant volume of water.
Therefore, if we fill in the sea bottom at the western foot of Cumbre Vieja and so cause the massive slide there to land on land instead of ocean, significant volumes of seawater will not be displaced across the Atlantic against our shores, and there will be no tsunami! Hey, we have a good place to deposit our garbage, our fill. Passing ships can leave off ballast. Huge tanker ships can pump hardening slurry, or even gravel, down at the foot of Cumbre Vieja. The more of the water volume we displace there by such gradual means, the less will be there to be kicked off by a sudden slide and made into a tsunami.
Time may be crucial—that deeply cracked slope could go at any time and we could then still lose our East Coast. It will take time to bring this solution to people’s attention, time to negotiate arrangements and international provisions, and time for the actual process itself—the physical mechanics of building an artificial landstrip to intercept the fall of the massive slide before it can abruptly displace the sea. Can this obvious solution even be gotten into enough public attention for discussions to start in the places where they need to start? Fortunately, a lot of time can be saved by deploying Beachbuilder (perforated pipe or hose with air pumped through, laid underwater so the resulting bubble curtain will intercept and slow nearby ocean currents so they lose momentum and drop their load of sediments in their lee—dumping them just where we want them to, filling in by volume much more and sooner than we can accomplish by shipping fill over to dump in at the foot of the volcano.
(Saving on transportation costs of dug-out fill: One solution would be to dig out several ports along Africa’s west coast, not only more inexpensively filling in the sea at the foot of the volcano, but boosting the world’s poorest regional economy by creating new centers for commerce and shipping.)
It’s not only our East Coast and other coasts along the Atlantic. It’s not only our West Coast vis-a-vis Hawaii. There have to be dozens of situations where rapidly growing volcanoes in or by the sea have built up huge slide potentials—for that, read “tsunami potentials.”
Note that what we propose here would not have prevented either the Japanese or the Indonesian tsunamis, nor will it prevent a mega-tsunami from the great Cascadian quake currently threatening our Pacific Northwest—those are subduction faults where one continental plate is slipping over another.
Nothing in our present science and technology can do much about tsunamis from subduction quakes. But it is already well within our means, and with but tiny expense, to save millions of lives and vast destruction at many places around our world, simply by going about filling in under where large landslides are threatening, and filling in under them to insure that those slides land on land instead of displacing cubic miles of seawater which then have to crash somewhere else. If we shrug away the opportunity to save these situations and those millions of human beings, then what happens is indeed our own fault.