Thursday, December 30, 2004

Tsunami Perspectives

"For millenniums, the sea's waves have battered the coastlines of the world, here cutting back a cliff, there stripping away tons of sand from a beach, and somewhere else, in a reversal of their destructiveness, building up a bar or a small island. Unlike the geologic changes that take millions of years to bring about the flooding of half a continent, the work of the waves is perceptible during the brief span of human life; the sculpturing of a continent's edge is something we can all see for ourselves." -- Rachel Carson, 1951

Many Pensacola area people I know, victims themselves of the recent hurricane season, are eager to contribute to relief for the victims of the Christmas tsunami. A helpful list of respected world relief charities is provided in the New York Times.

To that, John Gunn adds in his email letter that Gulf Breeze mayor Buzz Eddy has made arrangements to receive donations at Gulf Breeze City Hall. Details will follow soon, I am sure.

No sooner had the Red Cross predicted the death toll will rise above 100,000 and half a million more injured in the horrible tsunami tragedy, than the BBC reports, "New figures reveal at least 112,000 people died in Sunday's ocean disaster."

Still, the melancholy numbers continue to rise.
Across the region thousands remain unaccounted for since the 9.0 magnitude undersea earthquake off Sumatra that forced a wall of water smashing into coastlines as far away as east Africa.
One of the biggest-populated areas still cut off from outside help is Sumatra itself:
In Sumatra, the Florida-sized Indonesian island close to the epicentre of the quake, the view from the air was of whole villages ripped apart, covered in mud and seawater. In one of the few signs of life, a handful of desperate people scavenged a beach for food. On the streets of Banda Aceh, the main town of Sumatra's Aceh province, the military managed to drop supplies from vehicles and fights broke out over packs of instant noodles.

Major-General Endang Suwarya, military commander of Aceh province, said after flying over the stricken region that 75 per cent of the west coast of Sumatra was destroyed.
A Canadian newspaper also reports that "the U.S. State Department said 12 Americans died in the disaster — seven in Sri Lanka and five in Thailand. About 2,000 to 3,000 Americans were unaccounted for."

A vivid account in the UK Guardian says --
Aid workers arriving in the region are being confronted with devastation - entire towns and villages razed, and countless people - some of them with cuts and broken bones - searching desperately for clean water and food on streets covered in debris and dead bodies.

With at least 5 million people in need, it is already one of the biggest humanitarian exercises in history, with 60 nations having pledged over $220m (£114.5m) in cash and hundreds of millions more in emergency supplies.
[Update: The Springfield, Mo., News-Leader is carrying a helpful comparison of the challenge confronting international aid organizations. "'The army of relief workers probably will need to be 10 times the initial federal help to Florida in last summer's spate of hurricanes,' said Joe Myers, a former Florida disaster-response chief. 'That means starting with 50,000 relief workers, then building to even more.'"]

The disaster seems likely to worsen as bacteria and viruses spread among the panicked, thirty, and starving survivors. From the Seattle Times:
For reasons not entirely understood, natural disasters are rarely followed by epidemics of communicable disease and very high mortality frequently seen in man-made catastrophes such as civil wars, genocide and involuntary displacement of whole populations.
* * *
Large numbers of corpses themselves pose little, if any, health threat. Putrefying flesh does not create disease-causing pathogens or spread them.

The real danger is from infections already present in the population at low rates that can be spread rapidly in the absence of proper sanitation.

Among the waterborne ailments linked to floods, the WHO cites bacterial and viral diseases such as cholera, typhoid fever, hepatitis A and leptospirosis, the latter of which can be spread through the urine of rodents attracted to flood debris.

How well people fare will depend in large part on decisions being made in the next few days or weeks as local health authorities and outside agencies work frantically to provide water and rudimentary sanitation to the homeless and destitute.
The New Yorker is sharing a unique historical perspective on tsunamis and closely related sea wave hazards by reprinting a 1951 article written by Rachel Carson for the magazine. For me, it was oddly comforting to read Ms. Carson's lyrical prose describing how such tragedies have been with mankind almost as long as time itself, even as muted images of the horrible Christmas tsunami were re-playing over and over on my television screen. Here is a snippet:
For millenniums, the sea's waves have battered the coastlines of the world, here cutting back a cliff, there stripping away tons of sand from a beach, and somewhere else, in a reversal of their destructiveness, building up a bar or a small island. Unlike the geologic changes that take millions of years to bring about the flooding of half a continent, the work of the waves is perceptible during the brief span of human life; the sculpturing of a continent's edge is something we can all see for ourselves.
* * *
The sea waves that have fixed themselves most firmly in the human imagination are the so-called tidal waves. The term is popularly applied to two very different kinds of wave, neither of which has any relation to the tide. One is the seismic sea wave, produced by an undersea earthquake; the other is an exceptionally vast wind wave—an immense mass of water driven far above the normal high-water line by winds of hurricane force.
* * *
The writings of man contain frequent mention of the devastation of coastal settlements by sudden great waves. One of the earliest on record rose along the eastern shores of the Mediterranean in 358 A.D., passed completely over islands, and flooded low-lying shores, depositing boats on the housetops of Alexandria, and drowning thousands of people. An hour after the Lisbon earthquake of 1755, Cádiz was visited by a wave that is said to have been fifty feet higher than the highest tide. Waves from this same disturbance travelled across the Atlantic, reaching the West Indies in nine and a half hours. In 1868, a stretch of nearly three thousand miles of the western coast of South America was shaken by earthquakes. Shortly after the most violent shocks, the sea receded, leaving ships that had been anchored in forty feet of water stranded in mud; then the water returned in a great wave and the ships were carried a quarter of a mile inland.

This withdrawal of the sea from its normal stand is often the first warning of the approach of seismic sea waves. Natives on the beaches of Hawaii on the first of April, 1946, were alarmed when the accustomed voice of the breakers was suddenly stilled. They could not know that this recession of the waves from the reefs and the shallow coastal waters was the sea's response to an earthquake on the steep slopes of the Aleutian trench, twenty-three hundred miles away, or that in a matter of moments the water would rise rapidly but without surf, as though the tide were coming in much too fast. The rise carried the ocean waters twenty-five feet or more above normal high tide. In the open ocean, as is characteristic of seismic sea waves, the waves produced by the Aleutian quake were only about a foot or two high and would not be noticed from a vessel. Their length, however, was enormous, the distance between crests being about ninety miles. It took the waves less than five hours to reach the Hawaiian chain, so they must have moved at a speed of about four hundred and seventy miles an hour. Along the shores of the eastern Pacific, they were recorded as far into the Southern Hemisphere as Valparaíso, Chile; the distance, eight thousand and sixty-six miles from the epicenter of the earthquake, was covered by the waves in eighteen hours.

The storm waves that sometimes rise over low-lying coastlands in hurricane zones are accompanied by a rise of the general water level, forming the so-called "storm tide." The rise of water is often so sudden that people have no chance to escape. These waves claim about three-fourths of the lives lost in tropical hurricanes. The most notable disasters caused by storm waves in the United States were at Galveston, Texas, on September 8, 1900; on the lower Florida Keys, on September 2 and 3, 1935; and in the Atlantic Coast hurricane of September 21, 1938. The most fearful destruction by storm waves within historic time occurred in the Bay of Bengal on October 7, 1737, when twenty thousand boats were destroyed and three hundred thousand people drowned.
For an even broader perspective, we're now told that scientists at the Jet Propulsion Laboratory have calculated that the tsunami affects everyone on the planet. Quake's Power Speeds Up Earth's Rotation and Shortens Our Days is the headline in The Scotsman. The effect is unlikely to be noticed for a few thousand years, however.
Richard Gross, a geophysicist with NASA’s jet propulsion laboratory in California, said that a shift of mass towards the Earth’s centre had caused the planet to spin one millionth of a second faster and to tilt about an inch on its axis.

He added that when one huge tectonic plate beneath the Indian Ocean was forced below the edge of another, "it had the effect of making the Earth more compact and spin faster". Days will get shorter by a fraction of a second, Mr Gross said, although the effects are probably too small to be detected by hi-tech global positioning satellites that monitor changes in the Earth’s spin.

The poles travel a circular path that normally varies by about 33ft, so an added wobble of an inch is unlikely to cause long-term effects. "That continual motion is just used to changing," Mr Gross said. "The rotation is not actually that precise. The Earth does slow down and change its rate of rotation."

When those tiny variations accumulate, planetary scientists must add a "leap second" to the end of a year, something that has not been done in many years, he added.
Not all agree on the exact measure of spin and tilt caused by the tsunami. "We won't know for weeks," geophysicist Thomas Herring of the Massachusetts Institute of Technology told New York's Newsday. "The most accurate measurements will take about three weeks to get all of the data processed. So it's a guess, as of now."

But, as Rachel Carson's fascinating essay reminds us, the sea also exerts a countervailing force --
The very movement of the water over the bed of the ocean, over the shallow edges of the continents, and over the inland seas carries within it the power that is slowly destroying the tides, for tidal friction is gradually slowing down the rotation of the earth. In the earliest days, it took the earth a much shorter time—perhaps only four hours—to make a complete rotation on its axis. Since then, the spinning of the globe has been so greatly slowed that now, of course, a rotation requires about twenty-four hours. Mathematicians say that this retarding will continue until the day is about fifty times as long as it is now. And all the while the tidal friction will be exerting a second effect; it will be pushing the moon farther away, just as it has already pushed it out more than two hundred thousand miles.
The tsunami tragedy has awed the world. It demonstrates the fragility of our planet and the power of nature. Most of all, I think, it reminds us of the interdependence of all mankind, and life itself, on earth.

Just as with the lowly worm Convoluta roscoffensis, whose mysterious ways Rachel Carson describes at the end of her New Yorker essay, we are all destined to "live out... life in this alien place, remembering in every fibre... the tidal rhythm of the distant sea."

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