How Nature Changes History. (Week in Review Desk)(The World: In Disaster's Wake) Donald G. Mcneil Jr..

Full Text: COPYRIGHT 2005 The New York Times Company

WHAT follows in the wake of a tsunami? The death of a nation? Secessionist warfare or, conversely, the unexpected drift of warring parties toward a peace table? A surge in Islamic fundamentalism?

If the past is any guide, the response to the shock of Dec. 26 will loom larger in history than the wave itself. Disasters rip away social moorings as harshly as they tear children from their mothers' hands, and while faceless nature may be to blame for the first blow, governments may reap the political whirlwind that follows it.

In this case, the wave that rose out of the Andaman Sea broke over some remarkably fragile societies:

Indonesia's Aceh province had been under virtual martial law, largely closed to the outside world as 40,000 troops hunted separatists.

Sri Lanka was cut in two by civil war, and new killings had raised fears that a two-year cease-fire was collapsing.

In Thailand, fighting between the government and Muslim rebels not far from its beach resorts claimed at least 500 lives last year.

And the Maldives, a nation of 1,190 coral islands averaging three feet above sea level, already feared the slow rise in the surrounding waters caused by global warming.

Disasters have often deflected the course of history. Three whole civilizations that met watery dooms occurred to Dr. Brian M. Fagan, an archaeologist at the University of California at Santa Barbara.

The least-studied of these cataclysms took place in 5500 B.C., when the Mediterranean, rising as the last Ice Age melted, burst through the hills surrounding a brackish lake to the northeast, and created the Black Sea. Seawater probably poured for weeks through what is now the Bosporus, covering human settlements ringing the lake.

In about 1600 B.C., roughly three centuries before the Trojan War, the Santorini volcano, 200 times as powerful as the Mount St. Helens explosion, sent waves hundreds of feet high across the Mediterranean, devastating Crete, capital of the Minoan empire, its fleet and its coastal cities. Fatally weakened, the empire was later conquered by the Mycenaeans of the Greek mainland, who established the model for Western culture. (For example, Minoan doors had no locks, while Mycenaeans built citadels.)

And in the sixth century A.D., the Moche civilization, based in desert valleys in coastal Peru, may have been fatally weakened by a combination of earthquakes and El Nino storms that washed away hundreds of miles of irrigation canals from the Andes. A tsunami may also have flung their washed-away hillsides back ashore, forming dunes that blew over the valley farmland.

Sudden and shocking as they are, earthquakes, volcanoes and tidal waves are not the biggest forces in human history. Tiny microbes are more powerful. Plague undermined the medieval social order by killing a third of Europe in the 14th century, and the New World fell to the poxes and sniffles of conquistadors and Puritans, not to their muskets. Then there are political assassinations: a Serbian bullet precipitated World War I.

But winds and waves, even from average storms, can topple empires if timed perfectly -- usually catching a navy at sea or an army on the march. As Bryn Barnard, the author of ''Dangerous Planet: Natural Disasters That Changed History'' (Random House), noted, typhoons in 1274 and 1281 (later dubbed the ''kamikaze'' or divine wind) saved Japan by sinking Mongol amphibious assault fleets. In 1360, an English army was marching on Reims to crown Edward III the king of France when hail the size of pigeons' eggs stormed down, killing men and horses and taking the fight out of the superstitious Edward. Invasions of Russia by Napoleon and Hitler bogged down in harsh winters.

The Dec. 26 tsunami will probably not end a civilization. But it did worsen the prospects for a nation's existence. The Maldives, dependent on tourism, lost habitable islands and a quarter of its 95 resorts, and suffered damage equal to double its gross domestic product. The government's spokesman admitted that its future was in peril. (In 2001, Tuvalu, a nation of nine coral atolls, agreed with New Zealand that all 11,000 Tuvalans would resettle there.)

Several areas hit by the tsunami, particularly Aceh, contain some ''very dangerous and unpredictable social cocktails,'' said Paul Saffo, director of the Institute for the Future, a San Francisco-area research group.

The 1883 eruption of Krakatoa, he said, helped the cause of Muslim fundamentalists among the Indonesian nationalists already assassinating Dutch colonial planters and fighting their marines. That war was fought hardest in Aceh, on the north end of Sumatra, which practices a militant Islam linked to the Arabian peninsula, rather than the gentler mix of animism, Hinduism and Islam of Java, the island where Indonesia's capital, Jakarta, is situated.

''There was a sense that the old gods had failed them,'' said Mr. Saffo, who said he expected the new devastation to become ''a wacko magnet of enormous proportions with new cults founded'' in what is already an isolated rural area.

The Indonesian government's response ''has to be swift, effective and free of corruption or it will be a gift to the fundamentalists,'' he said. The American war on terror, Mr. Saffo argued, might fare better by outspending Islamic charities in Indonesia than by ''pouring money into the sand'' in Iraq.

Dr. Diane E. Davis, a professor of political sociology at the Massachusetts Institute of Technology, also foresaw change in Aceh, though she spoke in terms more political than religious. The 1985 Mexico City earthquake, which she studied, hastened the end of 71 years of autocratic rule by the Institutional Revolutionary Party.

In relief efforts run by the Mexican military and police, aid packages were brazenly stolen, and police officers were assigned to rescue sewing machines from a collapsed garment factory while bodies lay in its rubble. Instead of rebuilding merchant blocks in downtown Mexico City, the government tried to clear them for modern buildings.

The Indonesian soldiers now running relief in Aceh ''could be the same ones that had just been murdering people,'' she said. ''Imagine what that means on a face-to-face level.''

By contrast, in war-exhausted Sri Lanka, citizens may see a contest. The government and the Tamil Tigers each control a stretch of devastated coast: which will do a better job?

With the right amount of goodwill, though, disasters can be a unifying force, said Dr. Michael H. Glantz, an expert on early warning systems at the National Center for Atmospheric Research.

Perhaps the greatest success for a disaster, he pointed out, was spawned by two earthquakes that took place just three weeks apart in 1999. When one near Izmit, Turkey, killed 17,000 people, the first country to send aid teams was Turkey's ancient enemy, Greece. When Greece in turn had a quake, Turkey reciprocated.

Admittedly, some diplomatic groundwork had already been laid, but Greece's foreign minister said later that the tragedies sent both nations a simple message: ''We are all human.'' The warmer relations eventually led to talks over Cyprus and an end to Greek opposition to Turkey joining the European Union.

''Maybe there's a way to get the rebels and government in Sri Lanka to say 'We're in this together,''' said Dr. Glantz. Then he hesitated. ''But it doesn't really work like that.''

CAPTION(S):

Photos: Photos of victims of last weekend's tsunami were posted at a church near Nagapattinam, an eastern port in India that suffered widespread devastation. The bodies, which had not been identified, were to be cremated. (Photo by Harish Tyagi/European Pressphoto Agency)(pg. 1); A lithograph of the 1883 eruption of Krakatoa, an island volcano between Java and Sumatra. (Photo by Parker & Coward/Hulton Archive -- Getty Images)(pg. 4)