Monday, September 12, 2005

The Next American Quake

Earth, that living, seething, often inhospitable and not altogether intelligently designed thing, has again shrugged, and tens of thousands of Pakistanis are dead. That earthquake struck 10 months after an undersea quake caused the December 2004 tsunami that killed 285,000 in Asia. Americans reeling from Hurricane Katrina, and warned of scores of millions of potential deaths from avian flu, have a vague feeling — never mind the disturbing rest of the news — of pervasive menace from things out of control. Too vague, according to Simon Winchester.
His timely new book, "A Crack in the Edge of the World: America and the Great California Earthquake of 1906," teaches — reminds, really — that we should have quite precise worries about the incurably unstable ground on which scores of millions of Americans live. This almost certainly will result in a huge calamity, probably in the lifetime of most people now living.
Before the study of plate tectonics revolutionized geology just 40 years ago, that science, Winchester writes, was concerned with "rocks, fossils, faults and minerals that were scattered around simply and solely on the surface of the earth." But the surface consists of between — depending how they are defined — six and 36 floating plates, which Winchester calls "rafts of solid rock." The plates' slow movements are powered by Earth's molten innards, the boiling and bubbling radioactive residue of the planet's formation.
The plates grind against — and slide up on, or plunge below — one another. But not smoothly, which is the lethal problem. When friction freezes them for a while, stupendous energy builds up until, suddenly, plates unlock and the energy is released, sometimes in ways that seem to involve related spasms around the world.
On the last day of January 1906, that seismically dangerous year, an earthquake in Ecuador and Colombia of perhaps 8.8 magnitude on the Richter scale killed about 2,000. Sixteen days later there was a large Caribbean quake, followed five days later by one in the Caucasus, and on March 17 by one that killed 1,228 on the island of Formosa. On April 6 a 10-day eruption of the volcano Vesuvius began with rocks blown 40,000 feet into the air over Naples. Two days after Vesuvius subsided, San Francisco was knocked down, and 2,600 acres of it were then devoured by three days of fires. About 3,000 San Franciscans died then, four months before a Chilean quake killed 20,000.
San Francisco's quake was smaller than the series of shocks around New Madrid, Mo., over a few winter weeks in 1811-12. They were strong enough to ring the bells in a Charleston, S.C., church that was later destroyed in that city's 1886 quake. Scores of millions of Americans now live on the unstable faults that shook mid-America in 1811-12.

For San Francisco, the bad news is that the quake that killed 63 in 1989 (6.9 magnitude, compared with 8.3 in 1906) was caused not by the San Andreas fault but by a neighboring one. So the big menace, the San Andreas, has not recently lurched, as it surely will because it is moving, sporadically, in grinding concert with the Pacific Plate. Since 1906 there have been only five major earthquakes along the 750 miles of the San Andreas, and none in Northern California. The U.S. Geological Survey estimates a 62 percent probability of a quake in that area of at least 6.7 magnitude before 2032. Pondering the prosperous town of Portola Valley, south of San Francisco, exactly astride two of the most active strands of the San Andreas, Winchester, like many geologists who have warned the town, is fascinated by "humankind's insistent folly in living in places where they shouldn't."
After Earth's heavings subside, they reverberate in people's minds. Winchester says that after the 1755 Lisbon earthquake killed 60,000, "priests roved around the ruins, selecting at random those they believed guilty of heresy and thus to blame for annoying the Divine, who in turn had ordered up the disaster. The priests had them hanged on the spot."
The 1883 eruption of Krakatoa in what is now Indonesia fueled the growth of an extremist strain of Islam, bent on purging society of impurities displeasing to God. That strain has twice recently been heard from in Bali.
San Francisco's 1906 disaster prompted the explosive growth of a Pentecostal movement based in Los Angeles, a movement then embryonic but now mighty. Yet when A.P. Hotaling's whiskey warehouse survived San Francisco's post-quake inferno, a wit wondered:

If, as some say, G-d spanked the town
For being over frisky,
Why did He burn the churches down
And save Hotaling's whiskey?

Good question.


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