The Rift (32 page)

FOURTEEN

There has been in all forty-one shocks, some of them have been very light; the first one took place at half past 2 on the morning of the 16th, the last one at eleven o’clock this morning, (20th) since I commenced writing this letter. The last one I think was not as severe as some of the former, but it lasted longer than any of the preceding; I think it continued nearly a minute and a half.

Exclusive of the shocks that were made sensible to us in the water, there have been, I am induced to believe, many others, as we frequently heard a rumbling noise at a distance when no shock to us was perceptible. I am the more inclined to believe these were shocks, from having heard the same kind of rumbling with the shocks that affected us. There is one circumstance that has occurred, which if I had not seen with my own eyes, I could hardly have believed; which is, the rising of the trees that lie in the bed of the river. I believe that every tree that has been deposited in the bed of the river since Noah’s flood, now stands erect out of the water; some of these I saw myself during one of the hardest shocks rise up eight or ten feet out of water. The navigation has been rendered extremely difficult in many places in consequence of the snags being so extremely thick. From the long continuance and frequency of these shocks, it is extremely uncertain when they will cease; and if they have been as heavy at New Orleans as we have felt them, the consequences must be dreadful indeed; and I am fearful when I arrive at Natchez to hear that the whole city of Orleans is entirely demolished, and perhaps sunk.

Immediately after the first shock and those which took place after daylight, the whole atmosphere was impregnated with a sulphurous smell.

Extract of a letter from a gentleman on his way to New Orleans,

dated 20th December, 1811

The first big May quake— Ml, as it was later known— began at 5:19 Central Daylight Time as a sudden ten-meter bilateral dextral strike-slip motion along the whole length of the twenty-five-mile Reelfoot rift, a subterranean fault structure running beneath the Mississippi from Missouri to Tennessee. The Reelfoot rift intersects several other faults or fault segments— the Bootheel lineament, the New Madrid north fault, the New Madrid west seismicity trend, and others. The Bootheel lineament in turn intersects the fifty-mile-long Blytheville arch, an axial fault running more or less beneath the Mississippi.

The original Reelfoot slip triggered further slippage and upthrusting along all nearby faults, each fault contributing in its turn to the intensity of the destruction— over 150 miles of built-up tectonic energy cutting loose at nearly the same instant. The shock waves from this massive disturbance traveled across mid-continental North America with admirable efficiency.

Most earthquakes occur near the boundaries of the earth’s tectonic plates, the giant twenty-two-mile-thick pieces of the earth’s crust, which drift slowly and massively on the semi-liquid mass of the planet’s interior. The collisions of the earth’s plates throw up mountain ranges, cause deep fractures in the earth’s crust, and precipitate almost all the earthquakes in the world. California’s famous San Andreas fault runs along the boundary between the Pacific plate and the North American plate, which are grinding against one another as they move in opposite directions.

The quakes generated at the edges of plate boundaries tend to be limited in scope. The fractured nature of the earth itself tends to disperse the temblors, or channel them into a small area. The great San Francisco earthquake of 1906 was a stupendous 8.3 on the Richter scale, but most of the destruction was confined to a compact part of the Bay Area, and deaths were limited to about 700. The San Fernando quakes of 1994 were likewise restricted to a small area, and caused less than a hundred deaths.

But the Reelfoot rift and other mid-American fault structures are not situated on a plate boundary, like the San Andreas fault. They are square in the middle of a very solid continent, and when something hammers the bedrock of the Midwest, the North American plate rings like a giant bell.

There is nothing to stop the quake energy from traveling hundreds of miles from the epicenter. P and S waves leaped from the fracture zones at a speed of around two miles per second, and the terrifying Rayleigh and Love waves, though moving a little more slowly, propagated across the American continent and through the entire structure of the earth, met on the far side of the planet, then returned, circling the globe a half-dozen times before subsiding.

The particular structure of the Mississippi Valley contributed to the catastrophe. A hundred and ninety million years ago, the North American continent almost split in two along the line of the Mississippi Valley. Had this geological action continued, a rift valley would have formed, similar to the Great Rift Valley in Africa. But the continent seemed to have changed its mind. The rift never formed, but the geological action left behind weaknesses in the earth’s crust, including the tangle of faults around New Madrid.

The Mississippi River, magnificent as it is, follows the course of what once was an even more magnificent bay, a branch of the ocean that reached as far north as Cape Girardeau, Missouri. Over hundreds of centuries, the Mississippi gradually filled this bay with sediment, creating the Mississippi Delta that stretches from Cape Girardeau to the Gulf of Mexico. The sediment— soil, mud, clay, gravel, vegetable matter, sand— is in some places thousands of feet thick.

When the Mississippi periodically flooded and covered a part of the Delta with a new layer of soil, the soil was intermingled with water and air. Over the course of many years, the water and air normally percolate to the surface and disperse. But if the Mississippi flooded again before this percolation could take place, laying down another layer of a less permeable sediment— clay, for instance— then the water and air was trapped beneath the surface, and as more and more heavy layers of alluvial soil was deposited on top, this water and air was put under enormous pressure.

With layers of clay or other heavier sediment sitting atop a goo of soft soil mixed with air and water, the geology of the Mississippi Valley resembles nothing so much as a layer of bricks placed carefully on a foundation of Jell-O.

The bricks are perfectly stable, so long as nothing shakes the Jell-O.

But when the complex of fault structures beneath the Mississippi snapped, the carefully balanced structure was disrupted. Pressurized water and air blasted its way to the surface, resulting in the so-called “sand blows,” thousands of geysers bursting through the surface to loft water, sand, coal, ancient chunks of wood, and rocks far into the air. More water found its way to the surface in less violent fashion, as M1’s power liquified the alluvial soil.

It is common for sediment or fill to liquify during an earthquake. Otherwise solid structures, built on alluvium, suddenly find themselves supported by nothing more solid than soup. Sometimes they can tumble downhill like a winter tourist on an inner tube. Much of the property damage suffered during the Bay Area quake of 1989 occurred in the Marina District, a part of San Francisco built on fill.

All of the Mississippi Delta—
all of it,
from Cape Girardeau south— is alluvial soil. Structures everywhere suffered catastrophic failure. Levees, dikes, and flood walls were broken, or weakened. Riverbanks collapsed. Whole forests were laid low. Water geysering into the sky or welling up through the sediment poured off the saturated land to join rivers already filled with spring snow melt.

Even areas built on solid ground did not fare well. The Chickasaw Bluffs, standing above the Mississippi Valley in Tennessee and Kentucky, were subject to landslides that dropped trees, roads, and expensive houses into the valley below. Cape Girardeau suffered a failure of its flood wall, and the lower part of town was inundated. The old French town of Ste. Genevieve, south of Girardeau in Missouri, was likewise partially flooded, and lost several of its historical structures to the flood or to the quake.

The Mississippi town of Natchez, with its proud, pillared collection of antebellum mansions perched atop the loess bluff, windblown soil piled high in the last Ice Age, lost a small city park to landslide as well as a quintessential Southern mansion house, Rosalie, built in 1820. Natchez also lost its riverboat gambling venue when a landslide spilled right through the rough old port town of Lower Natchez and into the casino boat, sinking it at its moorings.

Buildings of unreinforced masonry are more susceptible to earthquake than any other type, and unfortunately the entire area struck by the quake rejoiced in tens of thousands of brick buildings, most of which were destroyed or damaged. Mobile homes were shaken to bits or pitched off their foundations. Frame buildings fared better than others, though some, in the worst-affected areas, were simply shaken to pieces.

Throughout the area, significant damage was suffered as a result of the failure of foundations. Most basement walls were not reinforced and simply caved in, the house falling atop them. Throughout the region, particularly in areas where the water table was high, houses had been set above the ground on small brick piers. The masonry piers either shattered in the temblors, or the complex motions of the quake walked the houses off their foundations and dropped them onto the broken earth.

Approximately a million people were in their automobiles when the quake struck, most of them heading home from work. In many areas the road systems were destroyed in an instant. Bridges and elevated roadways fell or were mangled; roads were torn across by fissures; right-of-ways were flooded. The roadways were packed with desperate people stranded in their vehicles, far from their homes, away from supplies of food and water.

Rail transport suffered as well. Bridges fell, tracks were torn or wrenched into pretzel shapes, depots were destroyed. The most economical and efficient method of getting food and other supplies to affected areas, by rail, was rendered temporarily unusable.

At airports, runways were destroyed, fuel depots ruined, control towers pitched to the ground, and hangars collapsed on aircraft. Radar installations were wrecked, or lost the ground lines by which they transmitted their data. Entire districts of the country disappeared from air controllers’ screens. Aircraft, stranded aloft when their destinations were turned to rubble, began to call frantically for controllers to find them a place to land.

Following the shattering catastrophe of the quake came the swift catastrophe of fire. Propane tanks spewed their explosive contents through shattered couplings. Unsecured stoves and water heaters marched from their places, spilling scalding water and breaking their gas connections. Underground oil and gas pipelines were broken. Above-ground storage tanks ruptured. The unexpected lightning storm over Swampeast Missouri struck forests and buildings alike. And shattered buildings provided tinder that could ignite a conflagration.

Winds fanned the flames. Shattered communications and inundated emergency communication systems ensured that the fires would go unreported or unnoticed until they had taken hold. Broken water mains meant there was no water available to fight the fires.

Conflagration took hold everywhere in the stricken land, and on every scale. Isolated barns and houses burned, small stores and large, small towns and large towns, and the city centers of St. Louis, East St. Louis, and Memphis. Thousands of people, trapped in rubble or with their retreat cut off by flames, died in terror. Forests and prairie took fire as well, and with the authorities concentrating on quelling fires in cities and towns, there was nothing to stop the flames in the countryside but what Nature provided in the form of rain and flood.

The author Robert A. Heinlein once mocked what he called the wooden fire escapes on Chicago’s apartment buildings, unaware that he was looking not at fire escapes, but at wooden back porches equipped with stairs. But Heinlein may have had the last laugh when Ml shivered a part of the city to bits. Though Chicago, well away from the quake’s epicenter, on the whole survived the quake fairly well, a fluke of geology carried the earthquake’s full power to the northeast district of Rogers Park, and the heavy wooden porches, dry as tinder after years of weathering in the outdoors, turned to flaming deathtraps.

After the shattering catastrophe of the quake and the swift catastrophe of fire came the slow-motion catastrophe of flood. The Mississippi and its tributaries were full with snow melt, and spring rains had saturated the soil. Sand blows and soil liquefaction brought subterranean water to the surface. And when the levees and dams broke, river water had nowhere to go but to spill across country.

Flood is a disaster slow enough so that people can normally get out of its way, but in this case broken road and communications systems made it impossible to manage proper evacuations. Flood caught tens of thousands in their homes, and tens of thousands of others were caught in the open, trying to get away from their wrecked homes or their stranded automobiles.

Nor was the flooding confined to the Mississippi alone. The Father of Waters has 250 tributaries, including many that are mighty rivers in their own right: the Missouri, the Arkansas, the Ohio, the Red, the Des Moines, the Illinois. Each of these rivers has its own system of levees, locks, dams, and reservoirs, and each was filled with spring snow melt. The tragedy of the Mississippi, the flooding and destruction and death, was repeated many times throughout the country, from Iowa and Illinois south to Louisiana.

And sometimes flood was as sudden as fire. The Carlyle Dam in Illinois failed completely, causing a multimillion-gallon wall of water to roar down the Kaskaskia. Mark Twain Lake spilled through the shattered Clarence Cannon Dam, roared over the town of Louisiana, Missouri, into the Mississippi, where it turned into a wave that obliterated Lock and Dam No. 24. The failure of Dam No. 24 in turn released the millions of gallons it had been holding, and the two united bodies of water spilled south toward St. Louis, already vulnerable due to the shattering of its floodwalls.