The rupture produced a quake of magnitude 6.0 - and though it did not kill anyone, it frightened millions, not least the government scientists who have the fault in their care.

They had expected this particular quake to have occurred years beforehand - and had thought a seismic event so unlikely at the time that most were at a conference in Chicago when it happened.

They rushed home, fascinated to examine their instruments, but eager also to allay fears that their drilling had anything to do with the tremors.

As every American schoolchild knows, the most notorious rupture of this same fault occurred nearly a century ago, at 5:12 a.m. on April 18, 1906 - an occurrence now known around the world as the great San Francisco Earthquake.

An entire city, a monument to the hopes and dreams of America's westward expansion, was destroyed by a mere 40 seconds of shaking.

It was an occurrence possessed of a historical significance that may well be matched by the tragedy now unfolding on the far side of the world.

But, curiously, it turns out that there were many other equally momentous seismic events taking place elsewhere in the world in 1906 as well.

Ten weeks before the San Francisco quake there was one of magnitude 8.2 on the frontier between Colombia and Ecuador; then on Feb. 16 there was a violent rupture under the Caribbean island of St. Lucia;then on March 1, 200 people were killed by an earthquake on Formosa; and then, to pile Pelion upon Ossa, Mt. Vesuvius in Italy erupted, killing hundreds.

But even then it wasn't over.

The grand finale of the year's seismic upheaval took place in Chile in August, a quake that all but destroyed the port of Valparaiso.

Twenty thousand people were killed.

Small wonder that the Chinese, who invented the seismograph and who tend to take the long view of all historical happenings, note in their writings that 1906 was a highly unusual Year of the Fire Horse, when devastating consequences are wont to abound, worldwide.

Given these cascades of disasters past and present, one can only wonder: might there be some kind of butterfly effect, latent and deadly, lying out in the seismic world?

There is of course no hard scientific truth - no firm certainty that a rupture on a tectonic boundary in the western Pacific (in Honshu, say) can lead directly to a break in a boundary in the eastern Pacific (in Parkfield), or another in the eastern Indian ocean (off Sumatra, say).

But anecdotally, as this year has so tragically shown, there is evidence aplenty.