A Crack in the Edge of the World (26 page)

The fault underlies all of these places. When Andrew Lawson wrote his earthquake report in 1908, he supposed that the San Andreas in fact petered out here, but his confusion can be excused. For in this area the fault ceases to be a neat and tidy trolley track, or even a pair of tracks running in parallel; it is very tricky to recognize. It does not appear to cause much by way of local seismic problems, nor does it seem to determine the local lie of the land—which is, in any case, a mess of mountains and valleys spreading in all sorts of directions at once.

But in fact the fault, or the fault zone, continues on its merry way for at least another 150 miles—the first part of which is unutterably
confusing, with a significance that must have been easy for a 1908 geologist to miss. Subsurface maps of this particular region, now that much of the fault geography has been worked out, show that the fault does indeed continue, but that it has the crazed aspect of a spider's web, or of a car's broken windshield. Newly identified sister faults hiss and sidle out from the main line, faults with names like the Pinto Mountain, the Garnet Hill, the Vincent, and the Arrowhead.

It was close by this point that the San Andreas may have had its first publicly acknowledged workout. No small amount of mystery attends the event, but it took place in the summer of 1769, at the very beginning of Spanish settlement of California, when an expedition of militarily supported Franciscans, led by Gaspar de Portolá, was pushing north from San Diego, hunting for an overland route to Monterey. On July 28, while they were camped beside the Santa Ana River, they were interrupted by a severe earthquake that, the explorer noted, “lasted about as half as long as the Ave Maria.”

A little more can be gathered from the diaries of two other members of the expedition: They were perplexed by the aftershocks that went on for a full week. Juan Crespi, one of the diarists, recorded feeling as many as a dozen shocks a day while his team was winding its way around the southern hills of Los Angeles and down into the San Fernando Valley.

From all this anecdotal evidence, and from comparisons that can be made with more recent earthquakes, it appears likely that what Gaspar de Portolá and his party felt was a series of magnitude 6 quakes that had resulted from movement on either the San Jacinto Fault or, more probably, the San Andreas Fault. If so, then the fault that has caused so much mayhem during all of California's existence showed itself to be capable of great fury to the very first explorers of the region. They were given a warning—one that they and all who visited subsequently chose pointedly to ignore.

AFTER ALL THE
topographic confusions to the east of Los Angeles, the San Andreas splits itself into two parts near Palm Springs, then repairs
itself again near the town of Indio and becomes one once more. And finally, following this, after all of the excitements back at the Parkfield drilling site, after the ample confusions of the Big Bend, and the terrible complexities that are apparent as its licks its way around to the east of Los Angeles, it arrives in the city of Indio itself.

There is little that is memorable about the most southerly town on the fault's long track; it is no more than a scalding hot little railway community, a town where they have festivals to celebrate the dates they grow and the tamales they cook, and precious little else. The fault steals through without remark and without much evidence of its passing. It realigns itself slightly, kicks back onto its customary course, and resumes its orderly journey down toward its southern end.

And then, quite without ceremony, it disappears. It vanishes away in a muddy little field, beside one of the more unusual physical phenomena that is to be found anywhere in the country.

The Salton Sea is an enormous brackish lake, thirty-odd miles long and fifteen wide, that was created in 1905 as a result of a very foolish and very avoidable accident. At the turn of the century a firm called the California Development Company built a series of large irrigation canals in far Southern California to divert water from the Colorado River, which was then very close to its outlet in the gulf known in Mexico as the Sea of Cortés. The basic idea was to help local farmers on the edge of a very-low-lying part of the Imperial Valley called the Salton Sink (a relic of an earlier inland sea, as it happens) to grow fields of well-watered asparagus and broccoli. The company would charge the farmers, the farmers would sell their products, and everyone, in the classically American way, would make money.

Except that, unhappily, on one memorably unfortunate day, the levees protecting the trunk canal broke, and the entire flow of the Colorado River poured down into Salton Sink—which was more than 220 feet below sea level, at almost the same negative altitude as Death Valley. The waters kept coming and coming for more than a year, until finally railway wagons loaded with boulders plugged the hole in the levee and the newly created Salton Sea stopped filling and began to do what it has been doing ever since—evaporating.

The lake today is an odd, vaguely unpleasant place, rich with a strange smell that somehow mixes heat with dankness, rimmed with broken-down towns made of rusting trailers, with a reputation for the widespread manufacture of that particular nasty and highly addictive drug crystal methamphetamine, known variously as ice, Tina, Tish, or crank. The locals are seemingly obsessed with constant stories of death (as in fishermen drowning during sudden storms, birds perishing in their hundreds of thousands, beaches made exclusively from the crushed bones of fish skeletons, various species of flora and fauna dying out as the level of salinity, which is already close to that of the Pacific Ocean, keeps on climbing in the hot and pitiless sunshine).

Down at its southeastern end, just south of a formidably unpleasant junkyard of a settlement called Bombay Beach—alive with seismometers and GPS sensors, since the fault runs right beneath it—lies a grassy field, a few yards from a levee that halts the occasional rainstorm-induced flooding of the Salton Sea, allowing farmers to grow a threadbare harvest of soybeans and alfalfa. Not far from the field is a large white building with chimneys that belch a continuous cloud of white water vapor. It is a geothermal energy plant, an electrical generating station that spins its generators with the steam that pours from the ground in unstoppable volumes, scalding hot.

The area is riddled with hot springs and geysers and blowholes—and in the field beside the levee there are scores upon scores of mud volcanoes. The Cerro Prieto Geothermal Area is centered here, and it attracts businessmen who believe they might profit from all this energy that is bubbling up—quite literally—from below. It attracts in addition a small number of the curious. The local chambers of commerce shake their heads in sad acceptance of the fact that, were the area less displeasing, the mud volcanoes of the Salton Sea could be as big an attraction as Old Faithful. But it is not a pleasing corner of the world: It is more than unlikely that the Salton Sea will ever come to rival Yellowstone, not by a long chalk.

This is the southern end of the San Andreas Fault. It vanishes here; it dives underground, heading southward deep below until it reaches the edge of what is left of the Farallon Plate, at the so-called Rivera
Triple Junction in the Mexican Sea, off Mazatlán. Its final fate is so very different from everywhere else on the 750 miles of its length that it gives rise to one final big puzzle.

Why the geysers, the bubbling mud, and the streams of superheated water? There aren't any of significance anywhere else on the fault—so why are there here?

These geological characteristics, of what is officially called the Brawley Seismic Zone, are much like the characteristics of the middle of Iceland, or parts of Hawaii, or northern New Zealand. They are the signature characteristics of a spreading zone—a place where tectonic plates are sliding away from each other, and where new material is welling up in between, all of it hot and volcanic and geothermally interesting.

But what, one might ask, is a spreading zone doing anywhere near a plate boundary where the dominant characteristics have to do with slipping and sliding and thrusting and (in the very far north) subduction?

The answer to this seems to lie in geometry—and in the simple fact that while the overall heading of the Pacific Plate itself appears to be in one direction, that of the San Andreas Fault is very slightly different and, moreover, different in different places.

Relative to the North American Plate, the Pacific Plate is heading in a direction that is 36 degrees to the west of north, and it is doing so at a rate of just a little less than an inch and a half a year. The San Andreas Fault, on the other hand, is generally moving rather more slowly, at about 1.3 inches every year. Moreover, and most important, it is moving on a heading of 41 degrees west of north, which is some 5 degrees away from the direction of the plate movement. This 5-degree discrepancy between plate and fault, and the difference in the relative speeds of plate and fault, brings with it a welter of geophysically created wrinkles—unexpected mountains, additional faults, unanticipated earthquakes—and a host of other features that are all a consequence of the imperfect nature of the world.

But in a couple of places south of Parkfield, the discrepancy is different from this mean. In the Big Bend area, for example, the fault
moves in an almost due northerly direction—and so its movement compresses the coast of California and thrusts itself inward in a way that makes mountains rise out of the solid ground. In the area beside the Salton Sea, on the other hand, the fault moves outward in the direction of the sea on a heading of almost 45 degrees west of north. Rather than compressing anything here, the relative heading of plate and fault takes each away from the other—and it causes stretching—extension, in other words—and the kind of phenomena—geysers and mud volcanoes—that are associated with spreading.

North of Parkfield the fault and the plate march along a broadly similar path, which is why the slipping and sliding between the plates is so much simpler to record. It is also why, since all is so firmly locked in place, there is so much devastation when movement finally occurs.

As it did in San Francisco, of course, on the morning of April 18, 1906, and, though generally forgotten, four memorable times before as well: first in 1836, in 1838, then again in 1865, and finally and much more destructively in 1868.

The event that struck so savagely on October 21 in that particular year—when a neighbor fault called the Hayward unlocked itself and suddenly moved—had long been known as the Great San Francisco Earthquake. It was a name that survived until the event was obscured in its notoriety by what was to happen, as all had been well warned it one day would, nearly forty years later.

I
N A HALF-HIDDEN COVE IN THE NORTH OF WHAT WAS
then called Alta California, in a bay six miles inshore from the Pacific Ocean, on the eastern side of a bluff that was protected from the cold sea frets by ranges of hills and sand dunes, there was once a patch of fertile grassland in which grew a particular profusion of a bright green herb. It was a kind of mint, its leaves highly aromatic and its tiny flowers attractive enough for a nosegay. Now properly called
Clinopodium douglasii
, it was given this name by the nineteenth-century Scots botanist David Douglas, the man who also gave us the Douglas fir and many types of primrose. He had been commissioned by the Royal Horticultural Society to collect plants to bring back to London, and he traveled widely along the Pacific Coast searching for specimens; but he met an early and inapposite death in Hawaii after falling into a hole and being gored by a bull that had fallen into it first.

In 1776, when a party of Spaniards journeyed north from their local capital of Monterey and came across this fertile and sheltered spot,
they thought of the pretty green plant as little short of miraculous. They took their cue from the local Miwok Indians, who seemed to use the plant for all sorts of cures, and by all accounts were delightfully healthy as a result. The Indians infused it into teas and decocted it into tisanes, they prepared poultices, munched it as a breath freshener, rubbed it on their skins to ward off wild animals, or wore it in their hair for cosmetic effect. The Spanish settlers followed suit (aside from the skin rubbing, which they found distasteful) and named the fragile little plant yerba buena, the “good herb.” And more than that: They named the well-sheltered bay beside these herb-rich meadows Yerba Buena, too, which might well have been the name it still enjoys today but for those vicissitudes of Californian history that ensured that it ended up as San Francisco.

Before settling civilians there, the Spaniards had already dispatched to the neighborhood the two essentials of their rule, the soldiery and the clergy, and constructed the kind of dwelling houses they thought appropriate to their respective needs. A fort was built on the southern side of the main entrance to the harbor,
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and the detachment of military men who had constructed it was ordered to remain there on sentry duty. Three miles southeast of the fort (and, as it happened, three miles southwest of Yerba Buena, too), in a valley filled with fruiting manzanita trees, a modest adobe mission house was thrown up, a Father Palou was appointed abbot, and a ceremony was held with, as the cleric noted, rifle fire taking the place of organ music and gunsmoke “supplying the want of incense.”

Ever since the Franciscans had taken over the Spaniards' missionary work in California from the Jesuits (the latter order was banned in Spain), there had been pressure to name something, somewhere, after their patron saint back in Assisi. None of the previously founded California missions—San Diego, San Juan Capistrano, San Luis Obispo, and San José most prominent among them—had apparently proved worthy. But in 1776, both by chance and design, there were two happy coincidences. The fort that had been set down beside the Bay was formally founded on September 17, which happens to be the day that Catholics commemorate the impression of Saint Francis's wounds; and the nearby mission was consecrated a month later, on October 9, shortly after Saint Francis's feast day. There was ample reason, then, to name both structures after the much-esteemed saint—one the Presidio San Francisco and the other Misión San Francisco, although the latter was more familiarly given the name Dolores, in commemoration of the suffering of the Virgin Mary. Both buildings still stand today, with the white adobe structure of the Mission Dolores the oldest surviving structure in the city that eventually spread and grew around it.