southwest arm of the fault extended nearly twenty miles south of Memphis. Originally, that segment was thought to have ended roughly forty miles to the north of the city. Nearly sixty miles long, this weak spot deep in the earth had been there all along, hidden and unnoticed, waiting to come to life.
Atkins and the others were shocked. The New Madrid Fault had nearly doubled in size.
One of Thompson’s computer-enhanced graphics showed a cross section of the earth’s crust.
“You can see how the velocity and direction of the waves changed as they neared the surface,” he said, studying the computer images on the screen. The lights were dimmed. The seismic waves had changed direction and picked up speed and power when they hit different rock layers. There appeared to be an unusually thick layer of soft sediments deep below Culp’s Hill.
“That’s the kind of focusing effect that can double, sometimes triple the velocity of the surface waves,” Thompson went on. “That’s why the shaking was so severe in that part of the city.”
“Can you delineate the fault any better?” asked one of the geologists from the University of Memphis.
Shaking his head, Thompson said it was too far down in the crust, nearly thirty kilometers. His imaging techniques were a lot like CT scans and sonograms. The images were created by piecing together faint echoes as the seismic waves were reflected from buried rock layers and faults. The images were rarely sharply defined; at best the fault could be seen only indirectly.
“About all we can say for sure is that the major pulse of seismic energy traveled in a southerly direction along a previously unknown fault. The epicenter near Mayfield, Kentucky, was the likely trigger.” He projected a map of Tennessee, Kentucky, and Missouri on the screen.
“The seismic waves really picked up velocity when they hit faulting deep below the Memphis area. It was like ringing a bell.”
The surprising thing to Atkins was that the damage hadn’t been far worse. The miles of sediment that covered the fault must have deflected or diffused the seismic energy. The exceptions were at places like Culp’s Hill, where it had literally burst through the crust.
Thompson used the analogy of spokes on a wheel. What he called the Memphis Fault was a new spoke of the New Madrid Seismic Zone.
Walter Jacobs said, “This is going to scare the hell out of a lot of people. How do we tell the public that Memphis is sitting right on top of a newly discovered fault? Anybody got some ideas on that?”
Atkins noticed the slight catch in his friend’s voice. His face was gray. The fear in the room was almost palpable. Atkins felt it, too.
“None of this goes public. That’s out of the question,” said Paul Weston. “There’d be an unnecessary panic.” It was the first time he’d spoken, the voice deep, strong, authoritative. Atkins was struck by his dark eyes, how they focused and rarely blinked. The man was impeccably dressed in a dark gray suit, vest, and wingtip oxfords. Most of the other earth scientists in the room were considerably more casual in their clothing. Jeans, loose-fitting sweaters, and Vibram-soled hiking shoes predominated. Weston looked more like a banker than a geologist.
“We need to make sure of our data before we make any public announcements,” Weston said. “I can speak for the entire commission in that regard.” He repeated his earlier admonition that none of this discussion leave the room.
“I disagree here, Paul,” Jacobs said, swallowing down the thickness in his throat. “Half the people in this city live in brick homes. There isn’t one high-rise downtown that’s built up to California’s earthquake code. We get a major shake, these people are gonna be buried. We got to let them know.”
“I’ve never thought it was a good idea to withhold information from the public, even when it’s potentially alarming,” Atkins said. “I’d rather err on the side of giving them all the data they can use. Even the most minimal things, like how they can reduce earthquake hazards in their homes.”
Weston looked up from his papers and seemed to be taking in Atkins for the first time. His brow furrowed. “It’s not a question of withholding information. It’s making sure that it’s accurate.”
“I’d say Guy Thompson’s computers have already done that,” Atkins said testily. He could tell that Weston didn’t like this line of discussion.
“What about aftershocks?” another geologist said impatiently. “That was a pretty big jolt this morning up by Kentucky Lake. A magnitude 5.1. I’d like to set up an array of seismographs to see what’s happening.” The idea was to saturate the area with instruments to get a precise read on the depth, direction, and intensity of the seismic activity.
“I couldn’t agree more,” said Guy Thompson. “We’ve had at least forty small tremors up there since five this morning, none of them much more than a magnitude 2, but a real swarm.”
“Let’s be sure to check the dam up there,” Jacobs said, irritated with himself for just remembering that important detail.
“I’ve already taken care of that,” Weston said.
Relieved, Jacobs nodded his head. “Glad to hear it. That’s one place we sure don’t want trouble.”
“Are we prepared to talk about energy projections?” one of the geologists asked. He’d been sitting quietly in a corner, writing notes furiously. He was young, late twenties, and wore a garish sweater. Atkins recognized him, but didn’t remember the name. He was from the University of Chicago.
Measuring how much energy remained locked in elastically strained rocks was a complicated, time-consuming procedure, but it was vital to calculating whether the potential for another big quake was still stored in the ground, whether it was wound up like a coiled spring.
Someone suggested doing a GPS survey to measure any horizontal or vertical displacements in the crust. The Global Positioning Satellite system allowed for minute measurements of changes in the earth’s surface, one of the best ways to check for rock strain. If the crust was rising, or uptilting, it meant energy was still stored in the ground.
“Anyone know when the satellite system’s back on-line?” Atkins asked. An unusually large solar flare had shut the system down several days earlier. Fallout from the flare had also played havoc with power grids along the East Coast.
“Four more days,” said a voice at the back of the room. “The solar wind is still very strong. None of the satellites are operational.”
Atkins turned around to see who’d just spoken. A woman was leaning against the wall in the back of the room. She had straight blond hair and was wearing a denim skirt and tweed jacket. Good-looking, about thirty. A briefcase and laptop were slung from her shoulder. No one had seen her enter.
Everyone in the room was dumbfounded to see Elizabeth Holleran standing there, wondering where she’d come from, how she’d gotten in.
Weston rose halfway out of his chair. “This is a private meeting.”
Holleran recognized three or four of the men from conferences they attended together. One of them came to the rescue. She vaguely remembered him.
“Hi, Elizabeth,” said one of the USGS geologists who’d flown in from California. “This is Doctor Elizabeth Holleran of Cal Tech and about the best trencher I’ve ever met. She’s doing some great carbon-dating work on the Pacific Coast near Los Angeles. Had a dynamite paper published on the subject a couple months back in
“I want to know how she got in here,” Weston said, his voice laced with anger.
Holleran apologized for the interruption. She explained about the tunnel and the door.
Weston got up, hurried to the door that led to the tunnel, and pulled it open. He saw the assembly of grad students, sitting on the steps. “I want you all out of here immediately,” he said, slamming the door and locking it.
“They really couldn’t hear anything,” Holleran said, sorry to get the students in trouble. It was impossible to hear through the closed door.
Weston repeated his request for Holleran to leave. “I’m sure you can understand why we’re meeting here and why we must insist on strict secrecy. You weren’t invited.”
“I need just five minutes,” Holleran said. “This is important.” She’d been wondering how she was going to do this ever since she got on the airplane the day before. She figured the best approach would be straight on, just lay it out and try not to fixate on the huge professional risk she was taking.
“I’ve been given data that predicted a major quake on the New Madrid Fault sometime around January twentieth. What I keep asking myself, what I can’t get out of my head, is whether the earthquake you just had
