Georgianna McKee woke in the dark to the sound of an old cast-iron dinner bell tolling low, growing faint, and finally falling silent. She felt the mattress moving beneath her body. She sat up and tried to be still. And she listened for footsteps outside. 

But on December 8, just after midnight, out in the northeast corner of Parker County, the only sound she heard was her own breathing. With a hitch in her step from a worn-out hip replacement, McKee, 78, moved through the small house her late husband built with stone slabs pulled from the pasture. She hit the floodlight switch in the kitchen and peered out the windows. No one was there. The bell was still, anchored to a cedar post sunk deep in the loamy soil. It was heavy enough that even the most violent storms couldn't make it ring. The only time it sounded was when she pulled the crank and called her husband to dinner.

"He'd be down at the barn, fooling with his horses and yelling at them, but he could hear that bell."

She pulled a jacket over her nightdress and stepped outside with a flashlight. She swept its beam over the trees, the creek running past the house, and the dinner bell, adorned with a fading eagle she'd painted years ago. There was scarcely a breeze. McKee shuddered in the cold and ducked back inside. For another hour she lay there, too stirred to sleep. This was the strongest one yet, she thought. 

The next day, she made a point to watch the news, as she always did after nights like this. In the day planner that tracks her schedule and doctors' appointments, she also dutifully penciled in the dates, times, and magnitudes of each earthquake she felt. Last night added a 3.6 to her running tally. 

In the nearly 35 years since she'd anchored her dinner bell on these 11 and a half acres, she'd never felt an earthquake until November 6, 2013. She could look back 150 years, and the historical record would bear no evidence of seismic activity in the area until now. Yet in the last month, there had been more than 20 quakes. 

"Boy, that's the big conversation at church and everywhere else," she says. "What's going on?"

• • •

Mingshu-YinDAMAGE DONE: Shallow earthquakes near Mingshu Yin's parents' house—a mile away from a disposal well—have cracked walls, split rafters, and ruptured a sewer pipe.

Overnight, something shifted beneath the oak and juniper hills about a half-hour northwest of Fort Worth, near Eagle Mountain Lake. Even the oldest of old-timers said they'd never felt anything like it. They'd always taken for granted the ground under Reno and Azle, two working-class towns with a little more than 13,000 residents between them. It was a fixed point in the community, worthy of remark only as it pertained to drought, or to the productive shale that underlies the whole land.

Now, it was as though something sleeping beneath had roused. It shook them awake in the night and scared their children.

When the tremors came, the people heard a concussion like thunder. Some likened it to a sonic boom. Others to a muffled explosion. It rattled windows in sills and pictures against walls. At first, a few would report sprinting outside, looking for the trucks that had surely collided with their homes. After a while, they marked the passage of each quake with weary resignation, wondering if perhaps this is how it would be now. 

Out on Cardinal Road, where the population gets sparse and the space between neighbors grows, Meredith Hull swore she could predict the tremors by keeping an eye on her donkeys, Larry, Moe, Curly, and Pinto. "Three hours before the quake hits, our animals go nuts. The horses and donkeys head to the north pasture and run and run. Our goats make all sorts of racket."

Through November and December, sometimes they experienced several a day. Sometimes a few days would pass in between, and all the while, the unlucky ones would trace lengthening cracks in their walls. Keding Yin, a retired coal mine engineer from northern China, bought his little piece of Texas next to Hull, and a few goats, too. He'd come here with his wife, Jie Chen, in 2001 to be near their daughter, Mingshu. "The first one, Daddy didn't know what happened," Mingshu says. "He thinks it's a bomb and called 911. Police came and said, 'What's going on?' " 

She had lived through the bucking and rolling of earthquakes in Los Angeles. This felt altogether different, like a single, violent dislocation. Mingshu, a GIS analyst at an engineering company, pulled up USGS' website and was struck by the shallow epicenters it detected near her parents' home. "A natural quake is like 10 miles down," Mingshu says. "This is three kilometers."

As the country west of Eagle Mountain Lake trembled with stunning regularity, Yin watched the damage accumulate. He found a rafter in the attic split right down the middle. A sliding-glass shower door shattered during one of the 3.6s. In the kitchen, the ceiling separated from the wall. And outside, a fracture splintered through brick and mortar alike, from roof to foundation. Every door in the house facing north and south wouldn't close. Yin knew his sewer pipe had ruptured when the scent of human waste wafted up through the floor. He and his wife stayed with Mingshu in McKinney, their home temporarily uninhabitable. 

In Reno, residents were advised to boil their water when a 10-inch main broke in two places and 40,000 gallons emptied into the earth. In Azle schools, the children practiced taking cover beneath their desks, just in case the big one struck and the roof collapsed. Whatever novelty the earthquakes held at first had been dissipated by claims home insurance wouldn't cover and the sound of thunder in a cloudless sky. 

By then, the seismic activity wasn't so mysterious. Folks in town were talking about the natural gas wells drilled all over Parker County, within eyesight and earshot of their homes. The word "fracking" crept up in conversation. The papers printed interviews with geophysicists who believed it was likely connected to faults triggered by deep oil- and gas-field waste disposal. These disposal wells ring Azle and Reno.

Back in 2001, when the Barnett Shale gas play first moved into northern Parker County, McKee and her late husband, Eddie, turned down lease agreements and the sums the landmen offered. But she knew now that a fenceline would not isolate her home from what was taking place around it. "Enough is enough," she said. 

"The first one, Daddy didn't know what happened," Mingshu says. "He thinks it's a bomb and called 911. Police came and said, 'What's going on?' " 

All along, the Railroad Commission, the state's oil and gas regulator, maintained it had "not identified a significant correlation between faulting and injection practices." But when the shaking didn't stop, it tweaked its stock statement in December to say that the correlation was not "definitive." Yet it remained at odds with everything else McKee had heard, not just from folks at church, but from the USGS.

Finally, she read in the Azle News that Railroad Commissioner David Porter would host a town hall meeting in the Azle High School auditorium on January 2. McKee resolved to go, determined to win back her quiet country life. 

That day, a passerby might have been forgiven for assuming the football team was about to play for the state championship. The parking lot around the stadium was almost at capacity, and still more vehicles were idling, waiting for the line to move. The antennae of news vans from Dallas and Fort Worth rose into a clear winter sky. Inside, state troopers, sheriff's deputies, and local police lined the walls as people filed in, until the murmuring of some 800 or more swelled to a din and filled the auditorium. They swapped earthquake stories and damage descriptions. They shook hands with neighbors. And they waited for someone in power to explain what had changed beneath their towns.

Commissioner Porter, a mild, graying former oil and gas
accountant from Midland, took the podium. The two other commissioners were absent. Chairman Barry Smitherman, then a candidate for state attorney general, was speaking before a Republican organization in Houston that afternoon. 

Porter thanked the audience in a soft, flat voice ill-suited for public speaking. "I also want to let you know that I am very concerned and involved in this issue," he said, interrupted by a raised voice from the crowd. 

"Who are you?" a man called. Porter started again, haltingly. "No, seriously, who are you?" 

"David Porter, Texas Railroad Commissioner," he responded to lusty applause. He continued. "But we have to base our actions on sound science and proven facts, not speculation that appears in some newspaper articles and some blogs. That's why we're here, to hear from you about your experience."

He took a seat at a table on the stage, flanked by commission staffers and local officials. First in the audience to speak was a big man in a ball cap named Jim Lasater. Gesticulating nervously, he asked how he could depend on the unbiased conclusions of the state, "since there's so much oil money that goes into the campaigns of elected officials." 

Lasater waited a few moments, the cheers of a restive audience at his back. When it quieted down, the event moderator, Porter's chief of staff, informed him that the meeting was for listening to residents, not for answering their questions. The mood turned, and the auditorium rang with boos and derisive laughter. 

As resident after resident spoke into the microphone, their stories were nearly identical. Almost every hand shot into the air when Dale Wood asked who'd heard the thunder as their homes shook. There was fear and anger in their words, and a sense that if the earthquakes had come to Austin, things might be different. They pleaded with the commissioner, trying to reason with him. "It seems to me the only way to figure out for sure if the injection wells are the problem is to shut them down and see if the earthquakes stop," one woman said. 

But when it became apparent that answers weren't coming, they slowly stood and walked out of the auditorium, the emptying rows a silent rebuke. McKee signaled to leave, and her niece and nephew escorted her out. "We knew we weren't going to accomplish anything."

But a week later, Porter made an announcement during a commission meeting that caused the residents of Reno and Azle to wonder if perhaps he had been listening after all. He'd heard their stories, he told his fellow commissioners, and now he pledged action to let them know the commission took the seismic activity in their towns seriously. He proposed hiring a staff seismologist to keep the commission abreast of ongoing research. "I would like to direct the executive director to immediately begin a comprehensive nationwide search to find the best candidate," Porter said, looking to his colleagues for a response. A few beats passed. "All right … thank you," Chairman Smitherman said. "Let's go to item 202."

• • •

texas-fracking-damadeA disposal well

The Texas Miracle began about a mile beneath Wise County, on the other side of Eagle Mountain Lake from Georgianna McKee. George Phydias Mitchell, son of a Greek shoeshiner and considered the father of the shale boom, was then a methodical wildcatter with a geophysicist's taste for experimentation. In 1981, he sank C.W. Slay #1 down into the Barnett Shale and was intrigued by what he found. Under 5,000 square miles of North Texas lay the remains of the Iapetus Ocean, swallowed by the subducting advance of continents that no longer exist. Its organic life was buried hundreds of millions of years ago beneath thousands of feet of rock, and transformed by time into hydrocarbons encased in a hard black shale. 

Mitchell saw vast potential and, over the next decade, drilled dozens of wells, probing the shale. He learned through trial and error how to coax natural gas from its pores by wielding the force of hydraulics to open long fractures, first with gels, then with hundreds of thousands—even millions—of gallons of water laced with sand and chemicals. His three-dimensional seismic surveys mapped up to 500 square miles, hunting for the sweet spots where the shale was thick and isolated between boundaries of limestone. Experience taught him to avoid the Ellenburger, a water-bearing formation below the Barnett into which his fractures emptied their pressurized hydraulic power. It was a geologic dead end with no gas but plenty of useless brine.

The Ellenburger did, however, have one very useful feature. The Barnett is a sodden play. When it is completed, a typical gas well may produce 2 million gallons of frack fluid and brine bubbling up from the formation. After that, the flow subsides somewhat. Still, for the rest of its productive life it can yield as many as 1,300 gallons of brine per day. This water is five times as salty as the ocean, and a spill would poison rivers and render land barren for generations, like the fields of Carthage. Handling vast volumes of it is the eternal struggle in the oil and gas fields.

But the Ellenburger, as a reservoir, has an almost inexhaustible storage capacity for the stuff. 

"If we didn't have this method of re-injecting saltwater, we could not produce the gas in the Barnett Shale or the oil in the Permian Basin or the Eagle Ford or anywhere else," says Jim Finley of Finley Resources, which operates oil, gas, and wastewater disposal wells across Texas. "It's paramount to produce."

As hydraulic fracturing moved to tight-oil formations in South and West Texas, and to dry gas shale in East Texas, it created a gargantuan waste stream—3.5 billion barrels in 2011, up from 46 million in 2005. Its cheap, effective disposal into deep subterranean realms enabled an energy renaissance in Texas. The state comptroller collected nearly $4.5 billion in oil and gas production taxes last year.  This unlocking of once-untouchable reserves of hydrocarbons has caught on in Arkansas, Pennsylvania, and North Dakota, among other states. 

For the first time in 20 years, the United States is producing more crude oil than it imports. Natural gas is cheap, and the supply is plentiful. Terminals for its import are being retrofitted for export. Transporting natural gas via pipeline made billionaires of Dallasites like Ray Davis, the majority owner of the Texas Rangers, and Kelcy Warren, Klyde Warren Park's benefactor. Acquiring mineral rights and interests in exploratory wells and flipping them to majors like Devon Energy put Trevor Rees-Jones, a Highland Park boy, on Forbes' list of the 400 richest Americans.

And none of this would have been possible if the EPA hadn't granted the industry's waste a landmark exemption from the Safe
Drinking Water Act in 1988. The fluid is laced with acids, solvents, and diesel, yet for regulatory purposes is considered non-hazardous. The benzene in the fertilizer industry's waste is regulated as a danger to groundwater. The same compound in oil and gas wastewater is not. A quarter-century later, Texas' regulatory environment could not have been more ideally suited for an oil and gas boom requiring the expedient and inexpensive disposal of billions of gallons of waste. Without it, there is no Texas Miracle.

• • •

For a time, the derrick lights shone in the Azle skyline. The drillers cleared pad sites. They lined up batteries of roaring diesel generators. They trucked in trailers full of sand and excavated acres of freshwater pits. They drilled near the high school and into the golf course. They burrowed beneath the municipal wastewater treatment plant. And the fruits of their work paid for at least half of the town's $4 million fire station. The royalties and lease bonuses paid down more than $2 million on the note for Azle's 18-hole golf course. It covered much of the tab for the town's new animal shelter. 

"While you are doing your studies, I would like to ask you to shut these wells down
and not make us, the citizens of Azle and Reno, the guinea pigs for the study."

And all the while, tanker trucks hauled the wastewater away, per the road repair agreement. XTO Energy would ferry it in 8,000-gallon loads to a disposal well less than half a mile from Reno's northern border. Down it would go, as deep as 10,000 feet, absorbed by the interstices of the Ellenburger limestone, flaring in a teardrop pattern through the formation, pinched at the top and ever widening at the bottom. It would spread outward slowly but inexorably, long after the last truck had emptied its tank.

And the question that the thousands living on this moving land had no answer for was this: did the byproduct of Texas' good fortune find some ancient plate boundary and release energies building for millennia beneath Alan Brundrett's Azle?

Brundrett thought someone had kicked the back of his chair at a city council meeting the first time he felt one. The room went silent. "I think that was an earthquake," he finally told the dumbstruck people gathered in the chambers. The second time, he was watching a scary movie. The windows clattered, and Brundrett swore he leapt a foot out his chair. "I thought it was an explosion."

The 911 call center was inundated. City Hall's phones rang constantly. "At first we're like, 'What exactly do you want me to do?' It's like complaining about a tornado. But once we started doing some research, our eyes got opened."

Years after Brundrett had invited the industry into his town as a councilman, he sat across a table from representatives of XTO Energy as Azle's mayor. The company men told him they'd need proof—hard scientific data—that their well was causing seismic activity. They would require a firmer connection than proximity to the epicenter before XTO would consider plugging an essential piece of infrastructure that cost millions to construct. He began to understand that answers and solutions would be slow in coming. 

In late February, the insurance agent and part-time mayor sat in a remodeled church, his desk where the pulpit once stood. His office was decorated with the kind of curios you'd find in a chain shop like Spencer's: a busty mannequin, a life-size green alien, a unicorn sculpture. He rattled off numbers, localities, and magnitudes by memory—a history of vital statistics for what academics refer to as "induced seismicity." 

"Common sense says these earthquakes are caused by injection wells," he said. "And if that's the case, they need to be shut down."  

His constituents understand massive industry. Many of them worked for blue chips like BNSF Railway and Lockheed Martin. But the packed high school auditorium proved to him that there was a limit to the consequences they were willing to accept. The bewildering appearance of earthquakes had taken a leap past that line. So Brundrett took his case to the Railroad Commission. He met with geophysicists from SMU. He even appeared on The Rachel Maddow Show to vent his frustration over a town hall meeting that he believed had "done more harm than good." 

But, in fact, three weeks after the town hall, the residents' disappointment had galvanized them.

To Brundrett's north, Reno Mayor Lyndamyrth Stokes boarded a bus bound for Austin before dawn. Born in Iowa, Stokes is plainspoken and sports a faint dogleg scar on her upper lip, inflicted by an irritable cocker spaniel. She found herself in a curious position. "I didn't ask to get tossed into the ring as an environmentalist." Yet the trainer of dogs and barrel-racing horses was with dozens of anti-drilling activists and locals, headed for the state capitol to bring their case before the Railroad Commission. 

The first chance she got, Stokes strode to the microphone and politely scolded the commissioners. "While you are doing your studies, I would like to ask you to shut these wells down and not make us, the citizens of Azle and Reno, the guinea pigs for the study," she said. "Our houses are not built to earthquake specs. We have no earthquake insurance. We are the ones who suffer the damage. So, please, please shut these down. For once make people more important than an industry." 

The others told stories of sinkholes deepening on their land and foundation problems canting their once-plumb homes. One man strummed a guitar as he warbled an interpretation of an Elvis Presley classic: "I'm in Azle … I'm all shook up!" But their audience seemed skeptical.

"This is an area with a lot of karsts in it, which is an interesting geological formation," said Commission Executive Director Milton Rister. "There are other things going on there. We've been experiencing an extreme drought in the state of Texas. I don't know whether that plays a part. I think that needs to be examined. The size of the lake has been greatly reduced. Lakes do have an impact on seismic activity." 

Chairman Smitherman informed them that all disposal wells within a 15-mile radius of the earthquakes had passed inspection, save one, and it was miles from the epicenter. They would continue to operate, he said, because nothing in Texas law gave the commission the authority to address earthquakes.

The experience was a punch to the gut for the traveling protest. Stokes boarded the bus home feeling deflated.

On a recent evening, she walks past the warren of offices in Reno's tiny city hall and into council chambers. "We're just Reno," she says. "Just a little bitty spot." She toes a hairline fracture that runs the length of the tile floor and jogs up the wall to the ceiling. Some of the other cracks have been fixed, but she won't let them touch this one. 

"I know they won't do anything about it, but I'm not gonna just sit here and wait to get shook apart," she says. "I'm gonna let 'em know every time a home is damaged, every time a new study comes out."

Stokes appraises the crack and decides she might stencil "Earthquake 2013" next to it.

"You know, it's odd," she says. "In Cleburne, when they stopped injecting wastewater, the earthquakes went away. In Ohio and Arkansas, they went away. But I can't get them to stop here."

• • •

Even for the Midwest, the earth beneath Ashtabula, Ohio, was notable for its utter stillness. No one in the blue-collar coal-port town had ever felt an earthquake, nor had the older generations passed down any stories of fleeting tremors. That's why John Armbruster, a seismologist from the Lamont-Doherty Earth Observatory, left Palisades, New York, in 1987 with a load of seismographs and steered for this town on Lake Erie's southern bank. A 3.8 had rattled Ashtabula's industrial area and its residents' nerves. The tremors came one after another, swarming over a countryside once thought immune to them. This kind of thing simply hadn't happened here until recently. Armbruster wanted to know why.

As soon as he arrived with his team, Armbruster arranged a seismic network near the epicenters. The highly sensitive equipment, however, was picking up confounding levels of meaningless background noise usually attributable to a construction site. "I asked around, and they said it must be the pumps at a well where they're injecting waste into the ground. And I thought, 'Oh, somebody is injecting waste in the ground right near the earthquakes? Interesting!' "

His suspicions sharpened when he learned that the disposal well was not only 700 yards from the epicenters, but it had also started injecting a year before the first tremors. Nearly 16 million gallons had seeped into a sandstone formation more than a mile underground. And there was a fault system less than a mile away. "They kept pumping, and they kept denying that they're doing anything," he says. "Of course, if they stop pumping, they're admitting it."

Alan-BranchettSECOND THOUGHTS: As an Azle city councilman, Alan Brundrett welcomed the oil and gas industry. As mayor, he's not sure it should stay.

As Armbruster continued to monitor the area, Ashtabula gradually quieted down. A burst of seismic activity was reported in 1995, but otherwise it looked like the worst had passed. The disposal well was shut down in 1994. But the legacy of the fluid pumped below was lasting. A massive underground plume had been on the move those last few years. Imagine the pressure exerted by nearly 90 million gallons of wastewater, pressing it downward and outward. Its movement through the porous rock formation may be imperceptibly slow, but it can travel miles if volumes are large enough.

In 2001, some 15 years after the first drop entered the disposal well in Ashtabula, and seven years after the last, the area experienced a 4.3 earthquake—its biggest yet. The sprawling slug of waste had traveled nearly four miles to a parallel fault. When it got there, the wastewater reduced the friction keeping the critically stressed fault stable. It was akin to placing a little extra pressure on the trigger of a loaded gun.  Armbruster and a colleague wrote a peer-reviewed paper about the tremors for the Bulletin of the Seismological Society of America in 2004. That's why Ohio reached out to him again in 2011 to report another suspicious sequence of earthquakes.

An hour south of Ashtabula, in Youngstown, bewildered residents were reporting unprecedented seismic activity. Armbruster was technically retired but was curious to see if it was a repeat episode of induced seismicity. The epicenters, he found, were all within a mile of a disposal well, which was pumping straight into a fault system. That explained why the tremors began within weeks, not months, of its first injection. "If someone gave me $3 or $4 million and said, 'Make some earthquakes,' I would do what they did in Youngstown," Armbruster says.

Pennsylvania's Marcellus Shale was in the midst of a natural gas bonanza. But it hosted few wastewater disposal wells because a less-permissive EPA had oversight in the state. As a result, much of the waste was crossing the border to off-load in wells near Youngstown.

When Armbruster told state officials about how close the epicenters were to the disposal well, it was shut down three days later. But on New Year's Eve, 24 hours after its closure was announced, a 3.9 hit Youngstown. Governor John Kasich ordered three other disposal wells in the area to suspend operations indefinitely. 

The story was much the same in Arkansas' Fayetteville Shale, near the towns of Greenbrier and Guy. A disposal well intersected a known fault and set off a swarm of tremors, culminating in a magnitude 4.7. Arkansas now maintains a 1,000-square-mile moratorium zone for disposal wells around the seismically active area, encompassing nearly half of the shale play.

Cleburne, just south of Fort Worth, saw 50 small earthquakes over a six-month span in 2009, all within about a mile of two disposal wells. According to a draft internal EPA report obtained by EnergyWire, the Railroad Commission worked with Chesapeake Energy, which voluntarily shut one well down. The commission allegedly weighed in again when another earthquake swarm touched off near Dallas–Fort Worth International Airport. Residents called 911, reporting "loud booming noises and shaking of the walls and furniture," and Chesapeake once more plugged a nearby well sited next to a fault. In both cases, the company denied that the evidence against it was conclusive.

Far to the east, the town of Timpson experienced a 4.8 on May 17, 2012, the most powerful earthquake on record for the region. Residents reported white-tailed-deer busts falling from mantels and collapsing brick walls. The epicenters were less than two miles from disposal wells that had injected more than a billion gallons of wastewater since 2006. 

Cliff Frohlich, a University of Texas researcher, identified a fault system nearby but didn't have access to enough granular geologic mapping to identify a specific culprit. That's often the problem in defining what constitutes, as the Railroad Commission puts it, "definitive" proof of man-made earthquakes. Oil and gas companies may map these areas carefully. But geologic knowledge is the competitive edge in the oil and gas fields, and the price of gathering it is dear. Those who possess it aren't inclined to share. 

This is doubly true when liability issues arise. Class-action lawsuits have already been filed against well operators in Cleburne and Arkansas. "It's not going to happen," Armbruster says. "If the operator of a well starts cooperating with me, he's admitting that he's causing earthquakes. His lawyers are telling him not to do it." 

That means researchers don't get their hands on data that could help them identify perfectly situated faults. They make do with what is publicly available, and the result is often an earthquake swarm tied to a disposal well by proximity, timing, and the historical absence of seismicity. Bolstering the connection is the grand sweep of seismic activity in the central and eastern United States. Between 1967 and 2000, the regions averaged 21 earthquakes per year greater than a magnitude 3. From 2010 to 2013, as the shale play spread from North Texas, there were 450, and 188 in 2011 alone. It's all compelling circumstantial evidence, yet it leaves room for plausible deniability. 

And there's no shortage of disagreement about some of the most basic questions surrounding man-made earthquakes. How destructive can they get? Is it possible to determine how much stress exists on a particular fault? Can they be brought under control? Starting in 1969, the answer looked as if it could be "yes." USGS partnered with Chevron for a first-of-its-kind experiment. Chevron's oil-field water-injection operation was triggering earthquakes in Rangely, Colorado. Researchers discovered they could cycle the tremors off and on by tweaking injection rates. A USGS researcher recently suggested that this might be one way to handle them. But his peers feared the unforeseen.

"Some people thought this was a dangerous conclusion that could encourage behavior that might not be safe to the public," Armbruster says.

The danger lies in the large earthquake accidentally set off, and its seismic waves triggering an even bigger one. The events of November 6, 2011, upended much of what the scientific community thought it knew and posed another troubling question: how much time can elapse between the first injection and a seismic event?

A 5.7 struck near Prague, Oklahoma, a small town west of Oklahoma City. It destroyed 14 homes, injured two people, buckled a federal highway, and, at St. Gregory's University, toppled one of Benedictine Hall's nearly century-old turrets. The students were having a homecoming dance inside when it came down at 10:53 that night. As they ran from the building, bricks rained down. Governor Mary Fallin sought a federal disaster declaration. Felt as far away as Chicago, it was the strongest earthquake in Oklahoma's recorded history, and the most powerful ever linked to a disposal well. It was presaged by a series of smaller tremors that began in 2010, with epicenters some 200 meters from active disposal wells. 

In complete contrast to other cases in which disposal operations were followed closely by seismic activity, the wells here had started up in 1993. It had taken nearly two decades of consistent injection to raise the subsurface pressure high enough to induce an earthquake. This changed everything. In dry but chilling academic language, researchers from the University of Oklahoma and Columbia University wrote that the incident should cause the scientific community to reconsider "the maximum possible size of injection-induced earthquakes … and the time scale considered diagnostic of induced seismicity."

Before Japan's Fukushima Daiichi nuclear plant went into meltdown in 2011, European countries like Germany and Belgium relied heavily on nuclear power. In the wake of that disaster, some countries began phasing out their nuclear programs and mothballing reactors. It's a cautionary tale, Armbruster says, that should be heeded. "People in the industry should worry more than they do now," he says. "There could be a case where it's so obvious that fracking and disposing of waste causes an earthquake that kills 100 people. And overnight, the rules change."

The most sophisticated investigation of an earthquake swarm the field has ever seen is taking place in Reno and Azle right now. Seismographs have been installed across the area, and have transmitted precise locations and depths of the epicenters. Before, the closest seismic station was nearly 60 miles to the south. The data it produced was useful, but the locations were inexact, with margins of error measured in kilometers. In the early maps, the earthquakes were sprawled across the area, south near Azle, north of Reno, and west near Springtown. But once Heather DeShon and Brian Stump set up their sensors, the buckshot spread collapsed into a tight little pattern just northwest of Reno, not far from Georgianna McKee and the Yins. It was all a mile or so from XTO Energy's disposal well.

DeShon and Stump are careful about pointing fingers, and their speech is littered with caveats. They have correlation, but what they need is specific, subsurface data. Stump says they need it to create a model that helps them understand how fluids get from one place to another, critical information for addressing induced seismicity and triggering. But it isn't clear they'll get that data from the companies drilling in the area.

"They might not collect something we think is important," DeShon says, "so maybe the data isn't even there." Stump adds that there is economic benefit for companies that track the data he and DeShon need. "Faults can be pathways for fluids, so you don't want to drill near faults." 

The industry has remained mum on the issue and the growing evidence that its practices have caused damaging earthquakes. Major operators like Chesapeake Energy declined to comment. Others didn't respond at all. XTO Energy, an ExxonMobil subsidiary, issued a statement expressing support for SMU's research. It did not respond to questions about a possible role for its disposal well in the tremors.

The ability to say with forensic certitude that a specific well triggered a particular fault may, in many cases, be impossible. Scientists know that the rate of felt earthquakes has risen by multiples. They know that in nearly every instance, shutting down a disposal well has resulted in a sharp drop or complete cessation of the tremors. And they know that Earth's crust is a geologic collage, assembled by the subduction of land deep beneath the surface, by the rise of mountains, and by the volcanism welding it all together. The boundaries of these crustal plates were buried and ancient stresses accreted. The rocks became dead and cold, and their energy was stored away. Maybe wastewater found the old boundaries and something finally gave. The fault would have moved only a centimeter each time, but it would have done so at a speed of several kilometers per second and sent waves through the earth like ripples through water.

• • •

North of Reno, a tanker truck down shifts and rolls onto the gravel entryway of the XTO disposal well. Its load sits low and heavy on the rear axle, and it kicks up a scrim of caliche dust as it crosses the site and pulls up behind another tanker, next to a battery of seven 40-foot tanks. A hose is attached to a nozzle at the rear of the tanker truck. The air is filled with the thrum of an engine that drowns out the idling semis. The driver climbs out of the cab and speaks with a man in a hard hat as thousands of gallons of fracking fluid and water sluice through the hose and down nearly two miles underground. 

In 15 minutes, it's empty. The tanker pulls onto Knob Hill Road, and another takes its place. In the first nine months of 2013, some 3 million barrels of wastewater were dumped into the well. According to Railroad Commission records, this pace has been maintained since the well was drilled in 2009. And XTO says the well continues to operate normally.

A few miles south, Georgianna McKee putters around her kitchen, putting groceries away, talking about earthquakes as though they are some form of inclement weather. She hasn't felt many in the last month. It's quiet again here. The shaking earth doesn't wake her anymore. SMU's sensors still detect seismicity, but at a level too faint to be felt by humans. But no one—not the scientists, not the oil and gas companies—can tell McKee it's over. No one can say this isn't the lull other small towns like Ashtabula have felt before. 

 When they kept pumping, the quakes returned. And when they stopped pumping, the quakes sometimes got stronger. The waste moved implacably through the earth years later, following paths science can't yet track, releasing pent-up stresses whose magnitudes it can't yet predict, slowly squeezing the trigger of a gun they can't see.