8.4 (2012)

by Peter Hernon

  They also had half a dozen portable seismographs and geophones, which would record the ground vibrations and convert them into electrical signals that could be captured on magnetic tape. The seismographs would measure the waves as they moved through the deep earth. Faults and other irregularities would cause the signals to slow down or speed up. This so-called “reflection” technique had been used since the 1920s to detect buried oil and gas formations.

  The other equipment consisted of two German-made “vibrators,” big gas-powered devices that looked like jackhammers. The machines rapidly pounded a flat metal plate against the ground, producing seismic waves. The seismographs and geophones recorded them.

  The idea was to use the varying wave patterns to map out, much like a CAT scan, what the fault looked like and how much fracturing of the rock had taken place. The data would project the fault’s length and breadth and help them determine how much strain energy remained in the ground; heavy fracturing and the degree to which the fractures had opened were dead giveaways that rocks were under severe strain.

  The three-man Army crew, all heavily armed, served as a security detail.

  When Atkins asked about the need for this, the pilot told them it was too dangerous to travel unarmed. “There’s been a lot of looting,” he said. “It’s going to take a while before we get things under control.”

  There were also reports of wild dogs roaming the countryside in packs, he said.

  Elizabeth felt a twinge of anxiety, remembering how close she’d come to being mauled in that creek bed near Blytheville, Arkansas. Like Atkins, she wished they had time to investigate whether the animals were reacting to something they detected in the ground. She wondered if the continued aftershocks had anything to do with their behavior.

  Or did they sense another big quake was coming?

  She put that troubling thought out of mind as the chopper flew right over Kentucky Lake. The water level had dropped a good thirty to forty feet, but water was still rushing through the smashed dam into the swollen Tennessee River.

  It was her first good look at the dam since the earthquake. She couldn’t believe how totally it had given away. The huge structure—gates, concrete walls, power station—had vanished. Only the twisted remains of the boat lock remained.

  She stared at the gray water, remembering how she’d almost drowned down there. The surface was still choppy with whitecaps. They were flying across the lake from east to west, against a strong wind.

  Elizabeth figured something more than the wind was responsible for all that boiling water below them. The turbulence extended as far down the wide lake as she could see.

  Atkins knew what she was thinking.

  “The ground is still incredibly active,” he said. “The lake hasn’t had time to settle down.”

  THE first stop was near Dexter, Kentucky, about forty miles west of the lake. Atkins remembered the countryside well. It was close to the coal mine he and Jacobs had descended to get seismic readings the morning before the earthquake.

  How long ago had that been? Three days? Four? He’d lost count.

  Working in teams, they operated the vibrators, moving them back and forth over sweep zones a hundred yards wide. They took readings at several sites. It was a cool day with the temperature in the mid-forties, but after ten minutes of trying to hang on to the bulky machines, Atkins and Jacobs were breathing heavily. The instrument packs they carried on their backs felt like they were filled with bricks. It was hard to take the pounding as the flat metal plate at the end of the vibrator, moving in a blur, struck the ground repeatedly. Every muscle began to ache—bones, jaws, teeth.

  Elizabeth monitored the seismographs and geophones. The readings were clean and clear. After several hours, they flew to another site closer to the point where the new fault intersected with the old one in the extreme northwestern corner of Tennessee about 120 miles from Memphis.

  The procedure was simple and not unduly hazardous. Using a posthole digger, they dug holes six feet deep and placed the sticks of explosive in them. The water-gel charge was as powerful as dynamite but much safer to handle.

  The charge was detonated by remote control from a distance of several hundred yards. The explosions, which blasted clumps of dirt and mud a hundred feet into the air, also sent seismic waves radiating deep into the earth just like a miniature earthquake. Traveling tens of miles, these waves were recorded on seismographs placed near the blast site. The array of geophones picked up the sound waves.

  They took turns, setting the explosive charges and detonating them. By three in the afternoon the sun was already low in the sky. The pilot was under strict orders from his base commander to be back in Memphis before nightfall. Too many people were shooting at aircraft in the dark. It had become a popular post-earthquake pastime. Several planes had been hit by automatic rifle fire in rural Tennessee and Kentucky.

  Before they had to leave, there was time for one more test shot. It was Atkins and Elizabeth’s turn to place the charge. Jacobs helped.

  As the helicopter crew watched from the safe distance, Elizabeth lowered the explosive charge gently into the hole they’d dug. She’d already wired the electric blasting cap to the condenser, which was attached to the stick of water-gel. By adjusting a dial, Atkins set the condensing device to receive the radio frequency that would detonate the explosives.

  As they started back from the hole, Atkins saw Wren frantically waving at them. About a hundred yards away, he was shouting something and motioning with his hands, holding them palms down.

  “Hit the dirt!” Jacobs yelled, instinctively realizing something had gone wrong.

  Atkins threw himself into Elizabeth, pushing her down just as the ground erupted behind them. The concussion knocked them breathless. Clods of dirt and mud rained down on them.

  Still gasping for air, Atkins staggered to his feet

  Wren ran out to meet him. “It was an accident,” he shouted. “Are you all right?”

  “What happened?” Atkins said. He was furious.

  “Something must have gone wrong with the blasting machine,” Wren said. “The ready-to-fire light blinked on. That’s when I started shouting to you. Then the charge went off. It just happened.”

  Just happened?

  Atkins didn’t believe it for a minute. The blasting machine wouldn’t send out a radio signal unless the red “fire” switch was deliberately pressed. The machine required a precise series of steps to detonate a charge. First you had to press a green “charge” switch and hold it down until the meter showed the device was fully deflected to 1,000 volts. Then, while continuing to hold down the “charge” switch, you pressed the red “fire” switch. It was definitely a two-hand procedure, not easy to make a mistake.

  Atkins shouted for Marshal, who hadn’t moved from his position by the blaster.

  “Why did you push the firing switch?” Atkins yelled. “You could see we weren’t clear of the blast site.”

  “I didn’t touch it,” Marshal said. “It was your job to set the frequency on the condenser. You must have screwed up.”

  Marshal was almost a head taller than Atkins and heavier through the shoulders and chest. Moving straight at him, Atkins ducked under a right upper cut and hit him in the chest. He hit him twice in the face, but Marshal didn’t go down. He fought back, throwing hard punches that Atkins deflected.

  Jacobs and the soldiers ran over and separated them.

  “You stupid sonofabitch!” Atkins shouted. “You could have killed us.”

  Marshal, bleeding from the nose, roughly pulled away from two soldiers who were trying to hold him.

  “I’ll sue your ass for slander you keep that up. You were careless. That’s all.”

  Atkins lunged for Marshal again and had to be held back.

  When Atkins had calmed down, the pilot took him aside. “I don’t much like that bastard any more than you do. I don’t know what happened,” he said. “Or who’s to blame. And I don’t much care. We’ve got to get
back to Memphis. I don’t want to be flying in the dark and get my ass shot out of the sky by some hillbilly who’s pissed because he lost his cabin in the earthquake.”

  MEMPHIS

  JANUARY 15

  1:00 P.M.

  BOOKER REACHED THE UNIVERSITY EARLY IN THE afternoon. He’d come with a companion, a small gray monkey that had started following him soon after he’d landed in Overton Park. Booker knew the Memphis Zoo was located there and figured the animal must have escaped from its cage during the earthquake. The monkey was shivering in the cold and Booker had given him one of the apples he’d brought with him. From that moment, the monkey stayed about ten feet behind Booker at all times and had trailed him to the university.

  It took him a while to locate the earthquake center. The campus was a mess. The damage was worse than anything he’d seen at Oak Ridge, which was bad enough. The front of the new library had fallen off. Buildings were down wherever he looked, and even though it was cool, he smelled the sickly sweet odor of bodies that hadn’t been pulled from the wreckage and were starting to decay. If they didn’t take care of that soon, he knew they were going to have an epidemic on their hands.

  When Booker finally found the earthquake center, he was told Walt Jacobs was in the field running tests and wouldn’t be back until later that evening. An armed guard also told him all the other seismologists were too busy to talk to him and denied him entrance to the building.

  Booker showed the guard his ID from the Oak Ridge National Laboratory. “I jumped out of a goddamned airplane to get here,” he said angrily. “You’ve got to let me in there to talk to someone.”

  The Army corporal shook his head. “Sorry, sir. I can’t do that.”

  One of the seismologists stepped outside to smoke a cigarette. In an instant, the monkey shot from behind Booker and scurried through the open door. Feeling the annex’s warm air, it was trying to get out of the cold.

  “Dammit,” the guard said, turning to give chase.

  Booker entered the building right on the soldier’s heels. He was still wearing his bright-red jumpsuit and boots. He carried a small backpack. A pair of goggles were suspended from his neck. He made quite an impression.

  As it ran about the library annex, the monkey kept up a frantic ear-splitting screech.

  Steve Draper, the president’s science adviser, stepped into the hallway to see what was the matter. He’d stayed behind to monitor the situation after the president left.

  “I want to talk to someone about the aftershocks,” Booker said, walking right up to him. He didn’t recognize Draper and assumed he was one of the seismologists. “Promise me, you’ll just hear me out.” He quickly explained who he was and why he was there.

  “I’ve brought some notes,” he said, rushing along with his description. “I’m fairly sure the best depth would be at a minimum of two thousand feet. The deeper the better. I did a little research before I left. I’ve been playing with a graph that plots the magnitude of an earthquake with energy released in ergs. The energy released by a magnitude 5.5 quake has an energy equivalent of about 10 ergs to the twentieth power. A nuclear bomb, a small one, say 2 or 3 kilotons, would release about the same amount of energy. The trick here will be to release enough energy along the fault so you get a modest earthquake. But not enough to set off a big one. I can make that happen. The geologists need to tell me how big a bomb is required to do the job and where to place it. That should be pretty straightforward number crunching. I’d do it myself, but I’m getting a little rusty.”

  Draper stared at him. He didn’t say a word.

  MEMPHIS

  JANUARY 15

  11:05 P.M.

  EVERYONE IN THE EARTHQUAKE CENTER WAITED nervously for Guy Thompson to begin. He and his small team of computer imagers had worked hours analyzing the seismic wave data generated by the many aftershocks as well as by the vibration and explosion tests Walt Jacobs’ team had carried out.

  Weston, as usual, sat with Marshal and Wren. They were armed with stacks of technical papers on the New Madrid Seismic Zone.

  Atkins had taken a seat as far as possible from Marshal. He still didn’t know what to make of that screw-up with the explosives. It seemed impossible that Marshal could have accidentally fired the blasting machine. But he didn’t like thinking about the only other option. Until he had time to sort it out, he resolved to keep a close watch on Marshal.

  Thompson, CD headphones draped around his neck, asked for the lights to be dimmed. He wore a pair of beautifully stitched blue and black cowboy boots and a green Western shirt with a white yoke. He’d let his raven hair hang down to his shoulders.

  His first image was a two-dimensional view of what everyone was calling the Caruthersville Fault where it intersected with a previously known segment of the New Madrid Seismic Zone.

  The fault appeared on the screen as if suspended on the grid—beautiful computer graphics.

  The rupture was thirty kilometers deep and extended on a northeasterly line into western Kentucky. It started roughly at Caruthersville, ran across the western edge of Tennessee and up into Kentucky. The fault line ended near Elizabethtown, about thirty miles from Louisville. Lexington was sixty miles away; Cincinnati, 105.

  “The total length appears to be about 180 miles,” Thompson said.

  Atkins glanced at Elizabeth. That was longer than the original estimate.

  When combined with the New Madrid Seismic Zone, the combined fault system reached into six states.

  “This is huge,” Thompson observed. “Nothing in North America compares. Not San Andreas. Nothing. The seismic data from other stations in the upper Mississippi Valley indicate aftershock activity on almost every segment of the New Madrid system. Most of it remains concentrated along the Caruthersville Fault.”

  A pall of silence followed. The scientists in the room were tired, wrung out. They’d been working for days in a city devastated by the earthquake, where the damage was all around them. Where dead bodies still lay in the streets. They were emotionally drained. It was hard for them to summon up the energy to respond to Thompson’s chilling data.

  Atkins thought it might be among the largest intraplate fault systems in the world. Several in Asia were longer. He never would have considered anything like this possible in the continental United States. And all those fault lines were quivering with seismic energy.

  It got worse.

  Thompson’s next image was another two-dimensional close-up of the Caruthersville Fault, the point where it intersected with one of the older New Madrid segments. Radiating from both lines were literally hundreds of smaller ones, so many they looked like veins connected to major arteries.

  “Those are stress fractures,” Thompson said. “In some places, they extend twenty miles or more. I’ve never seen such clear delineations. The seismic waves produced by the explosions slowed dramatically every time they hit one of these fractures.”

  Another image, one of the most dramatic of all, showed a series of sharp peaks that rose up like a mountain chain from the new fault zone. The peaks illustrated cumulative aftershock activity in that area. Each of the taller peaks represented a minimum of twenty aftershocks that had occurred in roughly the same twenty-square-mile area. The proportional ratio was less for the smaller peaks.

  As she listened, an oppressive gloom settled over Elizabeth. The complex network of faults and fractures indicated a large amount of strain energy was still in the ground.

  “Can you tell us, estimate, how much energy’s been released?” she asked.

  Thompson had been waiting for that question. He knew the answer was going to hit hard.

  “Our analysis suggests the release of slightly less than 10 ergs of energy to the twenty-fourth power.” An erg was a standard unit of energy.

  “Impossible!” Weston exploded.

  It meant the 8.4 event had released about as much energy as the daily consumption rate for the entire United States or about as much as the stupendous volcanic eruption at
Krakatau in 1883, which darkened the earth’s atmosphere for years with ash and dirt. Only the 1960 Chilean earthquake, a magnitude 8.6, had released more energy, but its range was much smaller. Several hundred miles compared with more than a thousand for New Madrid’s 8.4.

  Thompson put it in perspective with another image he projected on the wall. “If the amount of energy released in a magnitude 3 earthquake were represented as a marble, the quake we just had would be a hot air balloon.”

  “And the ground’s still shaking,” Elizabeth said, almost to herself. It was hard to understand how any energy could remain after such a massive earthquake and the chain of strong aftershocks.

  Walt Jacobs pulled down a wall chart he’d used for lectures. It described, step by step, the chronology of the three great quakes of 1811-1812.

  Atkins was distressed to see how much his friend had slipped physically. He looked like he’d lost weight, especially in his thin face. He hadn’t shaved for days, and the beard and dark, sunken eyes gave him a wild, unkempt look. He seemed to be moving in a fog. Just before the meeting, Atkins had found him sitting at a desk, staring into space. He asked whether he’d heard from his wife. Jacobs shook his head. He looked scared. Atkins knew he’d been waiting to hear. There was still no word.

  “The first event, the one of December 16, 1811, was conservatively estimated to be in the magnitude 8.1 to 8.3 range,” Jacobs said. As soon as he began to talk, the fatigue seemed to fall off him. He was animated, well spoken. “We’ve estimated that single quake and related aftershocks released only half of the strain energy stored in the fault zone. Only half, ladies and gentlemen.”

  Elizabeth whispered to Atkins, “I don’t know if I want to hear the rest of this.”

  “Then the second big quake hit on January 23, 1812,” Jacobs continued. “Research indicates it was another magnitude 8-plus event. Like the first one, the shock waves were felt from the Rockies to the East Coast. We believe it released about sixteen percent of the available strain energy.”