Farewell to Tsunamis

Well, now I’m really behind the curve. I finally got crosstown and retrieved my copy of “ Tsunami: The Underrated Hazard“. However, at this late date, the Boxing Day Tsunami is all but off the radar. That’s too bad, cause’ I wasn’t FINISHED yet. Please indulge my slight monomania.
Submitted for your approval…a few snippets from the book. You may remember my fascination with anomalous boulders?

Most boulders found scattered across atolls consist of coral that is more than 1,500 years old; however, the boulders rest on an atoll foundation that is as young as 300 years. This fact suggests that the boulders were deposited by a large tsunami at the beginning of the eighteenth century. Local legends in the South Pacific describe the occurrence of large catastrophic waves at this time concomitant with the abandonment of many islands throughout French Polynesia. Significantly, the legends have the sun shining at the time of the waves…p 113

The Time Detective angle, you gotta love it. Onward to yet more boulders…

Of the world’s entire coastline, the West Coast of South America is one of the most prone to recurrent large tsunami…at Herradura Bay in the Coquimbo region, large tonalite boulders over 2 m in diameter are exposed within nearshore beach sands on a 200,000 year old interglacial terrace that is now situated 35-40 m above sea level. The boulders originated 2 km away, on the Coquimbo Peninsula, which was an island at the time the terraces formed. p 127

I’ve been fascinated by great inundations for decades. One of my brothers (I can’t remember which) told me the story of Lost Atlantis when I was just a little shaver. He also told me that scientists were worried it might happen to North America sometime in the next six months. Mmmm, family values.
I am now about to perform my first “Wolcott“…

“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.”

Yup. That’s the very first time I’ve quoted myself. Here’s the relevant excerpt from Bryant.
The Hokkaido Nansei-Oki Tsunami of 12 July 1993

The earthquake consisted of at least five intense jolts spaced about 10 seconds apart…two to five minutes later a tsunami with an average run-up height of 5 m spread along the coast of Okushiri Island and killed 239 people-many of whom were still trying to flee the coastal area. On the southwestern corner of the island, run-up reached a maximum elevation of 31.7 m in a narrow gully…Tsunami walls up to 4.5 m high protecting most of the populated areas were overtopped by the tsunami. Similar walls have been constructed in and around Tokyo and other metropolitan areas of Japan to protect urban areas from tsunami. They may be just as ineffective. p 170

By trapping the backwash within city precincts, the tsunami barriers may actually manage to drown a few people who might otherwise escape. It’s arguable…
Yet another recent killer wave, Papua New Guinea, 17 July 1998

…Tsunami flow depth averaged 10 m deep along 25 km of coastline reaching a maximum 17.5 m elevation. The wave penetrated 4 km inland in low-lying areas. In places, the inundation of water still 1-3 m deep 500 m inland…over 2,200 people lost their lives.

With pyrotechnics…

The wave was unusual because it was associated with fire, bubbling water, foul-smelling air, and burning of bodies. Eyewitnesses reported that the crest of the tsunami was like a wall of fire with sparkles flying off it…this sparkling was attributed to bioluminescence, while the foul odor was linked to a disturbance of methane-rich sediments in Sissano lagoon. The burnt bodies have been ascribed to friction…These explanations may not be correct. Subduction zones incorporate organic material, which is converted to methane by anaerobic decomposition. The sudden withdrawal of 1-2 m depth of water can cause degassing of these sediments, leading to bubbling water…The atmospheric pressure pulse preceding this wave may have been sufficient to ignite this methane. Certainly, the pulse was strong enough to flatten people to the ground before the wave arrived. Those exposed to this flaming wall of water would have been severely burnt before being carried inland.

Fascinating, horrible stuff. I think part of the horror stems from the sheer scale, the speed and lack of discrimination. Saint, sinner, mother, child, all grist for the wave’s maw. If I were still a Christian, it might make me question my sacred teachings. As it is, I actually feel better being snuffed out like an insect by vast impersonal forces. If this sort of thing were done intentionally, I would want better explanations than the ones I’ve been given.
So, I’m philosophically naive. We already knew that.
If you’re not totally fed up with giant waves, check out these…
http://users.tpg.com.au/users/tps-seti/spacegd7.html
http://www.drgeorgepc.com/