Just about everything in downtown San Francisco, from the Mission to the newly-constructed City Hall, from the quayside now known as the Embarcadero to North Beach and Telegraph Hill, was left smouldering.

The impact was worse, even, than the 9/11 attacks in New York. Imagine one-fifth of Manhattan in flames and you are nearer the mark. But, most chillingly, it could happen again, and on a vaster scale of human loss.

The death toll in 1906 was restricted to a few thousand, largely thanks to the time of day that it struck (5.13am) and the few hours' lag between the first tremor and the howling ravages of the firestorms. A new quake of similar magnitude (7.7 to 7.8 on the Richter scale), along either the San Andreas or the Hayward fault, could easily kill 28,000 people in what is now a more crowded, more precariously built, San Francisco Bay. And that, according to computer-model analysts, is a conservative estimate.

Yet the centenary had more of an air of celebration than sober remembrance. Tens of thousands of San Franciscans jammed into the downtown traffic island next to Lotta's Fountain, a memorial to a Gold Rushera entertainer, which became the rallying point in 1906 for survivors.

Elsewhere, restaurants offered $19.06 lunch menus featuring elements of the famous breakfast menu served on the fateful morning by the St Francis Hotel . . . scrambled eggs, stewed rhubarb, oatmeal, biscuits and bacon. The city's famed chefs came up with an 'On Shaky Ground' menu and, in one waterside eatery, a 'Fault Line Cake' with the cracking earth drawn in buttercream across the top.

Not everyone, admittedly, joined in this spirit of levity. ?I'm telling people this is not a Broadway musical, " the organiser of the Lotta's Fountain gettogether said a few days beforehand, in an effort to keep lounge crooners and vaudeville performers well away.

The city's mayor, Gavin Newsom, got into trouble for trying to arrange a Carlos Santana concert. Overall, though, the happy-go-lucky attitude to the centenary is entirely in keeping with the way San Francisco has regarded its greatest calamity from the very beginning . . . a mixture of denial, historical indifference, can-do entrepreneurial spirit, and a determination to focus on the optimism of the present and the future, not the darker resonances of the past. In the early years of the 20th century, San Francisco raced to rebuild, or 'upbuild' as the city fathers preferred to term it, and come back bigger and better than before.

By 1908, the last of the refugee camps and tent cities that housed the city's 200,000 homeless . . . half the prequake population . . . had been closed.

By 1915, the city was ready to host the Panama Pacific Exposition in a vast rococo folly of a building, the Palace of Fine Arts, constructed on newlyreclaimed land. The city somehow managed to gloss over or forget the extent of the damage it had suffered.

The official death-toll was never pegged at more than a few hundred . . .

it has been the tireless work of subsequent historians that has put the figure, more accurately, between 3,000 and 5,000. Some effort was made to suggest that the fires were significantly more damaging than the earthquake itself, or even that there had been no earthquake at all. This was partly for insurance reasons . . . fires were covered, acts of God were not.

Post-disaster outbreaks of typhoid, smallpox and plague were barely reported in the newspapers of the time. The grievous mistakes of the city's political class . . . notably, the disastrous decision to try to create firebreaks with dynamite explosions, which only spread the fire further . . .

were not dwelled on, nor did anybody make a serious attempt to learn from them for future preparedness. The appalling treatment of the city's Chinese and Japanese minorities, the declaration of martial law, the order to shoot suspected looters on sight . . .these things, too, have been allowed to lapse in the popular memory.

According to Philip Fradkin, perhaps the foremost historian of the 1906 earthquake, this historical forgetfulness bodes ill for the next Big One, which geologists say is more likely than not to hit San Francisco sometime in the next two decades.

?San Francisco was the city that nearly destroyed itself, and is poised to do so again for most of the same reasons, " Fradkin wrote in his recent book The Great Earthquake and Firestorms of 1906. Just like today's city, the San Francisco of 1906 was keenly aware of the risk of natural disaster, but chose largely to ignore it.

Fires had broken out regularly from the time of the Gold Rush, and earthquakes were familiar . . . one measuring 7.0 on the Richter scale struck in 1868.

Yet the city was built mainly of wood, along a meandering street plan that made escape, or access by firefighters, difficult.

On the fateful morning 100 years ago, the San Andreas fault shuddered just south of the city, generating two separate pulses. Instantly, many of the more precarious structures across the city were pulled to pieces. The first fire broke out when an overturned stove set a Chinese laundry alight on the south side of the principal tram lines along Market Street.

Firefighters rushed to the scene but realised to their horror that the underground water pipes had burst, reducing pressure in the nearby hydrants to just a dribble. Within hours, dozens of fires were raging uncontrollably, an inferno that melted buildings and human bodies on a scale only reproduced by the firebombing of German cities at the tail-end of the second world war. The fires raged for three days, at the end of which 28,000 buildings, three-quarters of the city, were burned to the ground. The calamity moved the rest of the country like no other before it. This was truly the birth of disaster relief, with shipments of food, clothing, tents and other essentials flooding in from all parts of the United States.

Historians like Fradkin see multiple parallels between San Francisco's experience a century ago and a modern disaster like Hurricane Katrina.

Like San Francisco in 1906, New Orleans was a raucous melting pot of a city with a thriving port, a corruption-tinged political culture, big pockets of poverty affecting minority groups, and a blindspot to its own vulnerability.

Last year's hurricane also brought out a militaristic streak in the government, at both state and federal level, a desire to crack down on ?looters" (motivated in both cases, Fradkin argues, by fear of widespread political insurrection amid the chaos), and fears that big business will win the fight to redefine the reconstructed city. It is already becoming apparent that New Orleans won't properly heed its disaster prevention needs as it rebuilds. ?Based on what occurred in northern California one 100 years ago, " Fradkin writes, ?New Orleans . . .

will eventually emerge bigger, brighter and more vulnerable to such catastrophes in future."