On The Slopes Of Vesuvius

Woke up this morning and turned on the tv. Saw the horror in coastal Asia. Richter 8.9. Dear sweet Jesus.

What could people have done? Can we ever hope to forestall this kind of catastrophe? Today, sadly, no. It would take a lot more technological moxie than we can muster to tsunami-proof a coast. Twenty third century super science may be up to the task, but we here today have a ways to go yet. Avoid seaside living? Nobody will listen. It’s nice by the sea.

I can think of at least one geologist, an Australian named Edward Bryant, who has been warning about the danger posed by tsunamis for several years now, and specifically in the area of Southeast Asia. Interestingly, it turns out that giant, inundating waves leave particular geological signatures, and Dr. Bryant has compiled an interesting file of data regarding them. According to him, Australia and parts surrounding would seem to have been hit fairly often in the last few millennia. He warns that, based on past evidence, they may be due for another. Oh, and the evidence, such as it is, shows that these waves were big.

How big? Really, really big. Like, one hundred and thirty meters big. Of course, that’s just when they come ashore. In deep water, that might translate to a three meter swell, with over a mile from peak to trough. You could ride it out in a rowboat.

Playing the role of Jor-El is, by definition, a thankless task. Dr. Bryant’s theories have gained him little love among his fellow geologists, who consider them controversial and wrong. Sadly, most of their criticisms seem to boil down to “He’s controversial…and wrong!”

I love science.

Let’s be real here. Could a wave really get that big? I mean, honestly. One hundred and thirty freaking meters? Well, yeah. Easily, if you cheat a little. The biggest wave on record was at a place called Lituya Bay, in Alaska. A massive, earthquake triggered rockfall at the head of the bay displaced an equally massive volume of water, which having nowhere else to go, promptly headed out to sea.

Lituya Bay is a long narrow body of water, much like a Norwegian fjord, and this constraining topography provided a focusing and amplifying effect. Afterwards, the wave’s peak local height was confirmed at seventeen hundred feet. They know this because only the trees above seventeen hundred feet didn’t get scraped off the mountainside. The wave diminished considerably on its way down the bay. Surprisingly, there were surviving witnesses, some sport fishermen, whose account can be found here.

But surely this is an exceptional case? Well yes, what with the topography and all, but other circumstances can lead to somewhat less spectacular waves that are still big and scary and deadly.

Bryant wrote a book a few years ago, “Tsunami: The Underrated Hazard”.
If any of you find this sort of thing at all compelling, you could do worse than to order the book. In it, he makes the point that not all tsunamis are created equal. They are generated by several quite different phenomena, with different energy levels, which can lead to quite different effects.

Most of us have a passing familiarity with the notion of earthquake generated tsunamis, such as the one that devastated Lisbon in 1755, or Port Royal in 1692.

There are also rockslide generated tsunamis such as the one at Lituya Bay, or the Storegga Slide. Storegga was a quite horrific event some seven or eight thousand years ago, a sudden slippage induced displacement of over one thousand cubic kilometers of rock and mud. Lacking the channeling effect of a narrow inlet, the resulting wave was “only” ten meters high when it finally came ashore in Scotland. But it made up in breadth and speed what it lacked in height, tearing into two hundred or more miles of coastline, and penetrating miles inland.

I’m sure the locals thought it was spectacular enough.

Still, neither of these phenomena pack enough power to generate the wave heights that Bryant is claiming. He therefore believes that “his” waves, hundred meter plus monsters, are the result of impact events. Given the right mass and velocity, a falling extra-terrestrial body could certainly provide sufficient energy for a monster wave. So we can know that such waves are at least possible. But is there enough evidence to show that they actually occurred?

Frankly, I don’t know. I’m not a geologist, and I don’t know enough to evaluate his claims properly. However, speaking as an interested layman, I’d have to say he sounds pretty plausible.

For instance, when he talks about what he calls imbrication.

You take a big seaside cliff with a notch cut in it, running from top to bottom. And you notice that the aforesaid notch, well, it’s full of boulders, great blocks of stone stacked higgledy-piggledy all the way to the top.

And you notice that those blocks of stone are not the same kind of stone that the cliff is made of. And you wonder how in the world those multi-ton blocks of foreign stone got up there.

When you’ve climbed to the top, you stroll inland across the gently rolling tableland, and you notice more of those damn stones, scattered here and there. And it gives you pause for thought.

If you’re Ted Bryant, your thought is going to be “That was one big wave”.

The book has plenty more of that. How about a ship’s bell, quite old by the look of it, found by rock climbers way the hell up a seaside cliff in western Australia? Could be a practical joke, I suppose, but an odd one if so. Who drags a corroded brass bell up a couple hundred feet of cliff, WEDGES IT INTO A CREVICE, and then just walks away? Aussies are a humorous folk, but are they THAT humorous?

Or what about vast piles of seashells and beach gravel, buried under more typical inland dirt, kilometers away from the seaside. Anthropologists assert that they are aboriginal shell middens, but Bryant says no way.

I do love a good mystery, and the mystery here is why sensible Aborigines would haul tons of beach gravel kilometers inland, just to throw it away.

At Jervis Bay, Dr. Bryant estimates a big one hit several centuries ago, and that it overtopped the headland there, making it at least four hundred feet high. That’s not of Lituya Bay magnitude, but we’re getting there, we’re getting there.

Bryant also notes (though he is enough of a sport to emphasize that this is hearsay evidence) that Aboriginal Folk Tradition has a few really rip-roaring tales of, wouldn’t you just know it, giant killer waves from the sea.

The Last Wave”, indeed.

Dr. Bryant has done yeoman service trying to warn people of what he calls “the underrated hazard”. Coastal fortifications would be impossibly expensive and don’t work. Ideally, people should recognize the danger and move inland. Be where the danger isn’t. He acknowledges that such a move is unlikely, and so suggests a number of modest, practical steps that could reduce, though never totally eliminate the danger from tsunamis. Boring civil defense and emergency planning type stuff. Coordinated communication and timely alarm type stuff. Bureaucratic solutions. I’m glad he tried. It really is the way to go.

Given that we can’t fortify vulnerable coastlines, and that people will continue to live in coastal areas, the modest, practical solutions are the only solutions we’ve got.

Which brings us to the (modest, practical) “running away really fast” option. If we disallow the Really Big ones, that actually looks doable with just a few more years of business as usual.

I have complained before about the impending wave of innovative electronic surveillance and communications tech, but that doesn’t mean I’m not aware of its potential benefits. Since these developments seem more or less inevitable to me, I suppose I’m just indulging my inner curmudgeon when I do so. Ubiquitous computing and video, localizer nets, transparent society, all connected, all the time, bah humbug.

There will come a day, and not in the twenty third century either, when even the meanest, most impecunious beachcomber will have access to a global comweb. And that fifty cent link will connect him with capabilities that make our current internet look like Western Union. Seriously. As Jim Bennett observed in “The Anglosphere Challenge”, what we’ve seen of the internet so far is just the warm-up act. The wheels haven’t even left the runway.

I can imagine radar satellites scanning the ocean surface for fast moving two meter swells, integrating their data with a network of triangulating seismometers and hydrophones. I can imagine such a network notifying whatever area was threatened, giving the ETA and predicted height and run-up of the wave. I can even imagine being able to reach the people in that area, as individuals, to warn them.

Someday, our hypothetical beachcomber may be screamed awake by his custom earbud, relaying a warning from the local node of Tsunami Watch.

It wouldn’t be much, but it would still be better than drowning. The downside, of course, might be that who you are and where you are is no longer ever in question. Ever.

Welcome to the modern Panopticon. It needn’t be all bad.


UPDATE: If you would like to contribute to the relief effort, the following blogs can put you in touch with people trying to help...

A Voyage to Arcturus

vichaar.org

The Command Post

UPDATE: After procrastinating for days, I finally trudged across town and retrieved my copy of "Tsunami" from storage. I'm mortified to report that my memory has played me false yet again. While a tsunami in deep water COULD have a three meter swell, its wavelength from peak to peak could range anywhere from six to three hundred miles. Typically, an earthquake generated wave in deep water will seldom top one meter in height. More geekery to follow, so stay tuned.

posted by Justin on 12.26.04 at 11:28 PM







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Comments

Commenting here in this thread here in Dean's World, Arnold Harris of Mount Horeb, WI, offers some historical perspective:

Anybody who wants to put yesterday's events off the coast of Sumatra in some true perspective should get Simon Winchester's "Krakatoa: The Day the World Exploded, Augsut 27, 1883." (ISBN 0-06-621285-5).

Winchester, a high quality Oxford-trained geologist and science writer, lays out in narrative format the subterranean events that led to the greatest explosion in recent history.

Krakatoa was -- and still is -- a geologically unstable volcanic island located in the Sunda straits between Sumatra and Java, not far from the epicenter of the geologic event that caused yesterday's tsunami.

At multiple times in history, this island has exploded with great violence, causing gigantic tsunamis that have crushed or drowned significant populations along shorelines both near and far from the epicenter of the action.

This has been caused by the geologic processes of Earth plate tectonics, in which heavier basaltic crust material underlying the oceans is subducted under lighter crust materials of the continents. What happens periodically but with lesser damage on Mount St Helens in the US Pacific northwest occurs with much more terrible consequences around the Pacific "rim of fire" and in other earth tectonic plate subduction zones around the world. Magma (melted rock materials), fed by the plate subduction process, rise up to fill chambers in volcanoes. Sometimes cold sea water gets into the chambers through small fissures and the superheated steam load overwhelms the weight of mountain, which acts as a sort of supersize natural containment building. That is when the geologic shit hits the fan and the volcano explodes. When that volcano constitutes and entire oceanic island, a mass-killer tsunami of gigantic proportions almost always results.

All of this what happened in 1883 in what was then the Netherlands East Indies, culminting in the terrible events of the late morning of August 27, when Krakatoa exploded and most of it disappeared.

The resulting tsunami crushed or drowned almost 40,000 people. Floating beds of congealed pumice (cooled lava ashes) were seen floating around the Pacific and Indian oceans for more than a year afterwards, sometimes bearing the corpses or skeletons of victims of the great explosion.

The sound of the volanic explosions that morning were recorded thousands of miles away, depending on specific atmospherics. The effects of the great waves were felt as far away as the coast of France. The dust that was ejected into Earth's atmosphere created incredible looking sunsets that were recorded by many a contemporary artist.

But the longest lasting effects of this natural disaster was that it gave rise to a wave of islamic fundamentalism among the muslim population of Java, Sumatra and other Dutch-ruled indonesian islands, resulting in otherwise inexplicable murders and attempted murders of westerners by fanatics who had otherwise led peaceful and uneventful lives, dressed for the occasion in pure white robes, and, when caught, unable to give the colonial authorities much of a rational explanation for their actions. (Almost an early dress rehearsal for much of what characterizes life in today's middle eastern countries.)

By the way. Anak Krakatoa ("son of Krakatoa"), is growing out of the Sunda straits in part of the seabed from whence Krakatoa had last been seen, 121 years ago. Anak Krakatoa is growing rapidly, with its volcanic vent smoking, smoking. And its magma chamber is filling, filling.

Arnold Harris
Mount Horeb WI
12.26.2004 1:50pm

I would have thought that the "shell midden" theory would be fairly easy to test. If these beds of shells had been laid down by human activity one would expect them to show signs of intelligent design in their shape, size and location. There should be multiple, discrete sites with the same design features, and some reference to them in the oral traditions of the Aborigines. If they were in fact middens, there should also be evidence of the prolonged human habitation in the immediate area that would have justified their construction.

On the other hand, if the shells were laid down by a giant wave one would expect to find a single band of material spread across a very wide area, and ancient stories of a huge wave hitting that part of the coast.

Andrew Zalotocky   ·  December 28, 2004 10:49 AM

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