He sent out 600 fliers and made, well, had to be around 100 phone calls, trying to attract people to his meeting on earthquake preparedness. And yet on a recent Tuesday night, he stood in the local school cafeteria and looked out at only a dozen or so people, including two women from the local extension homemakers club who had scheduled their own meeting on the topic a couple of weeks later.

“I think people are getting comfortable,” said Mr. DeTurck, a former Navy mechanic. “I mean, they have in California. They’ve become real comfortable with the shaking.”

Whether they have become comfortable is debatable, but the people of Guy, a town of 563 about an hour north of Little Rock, have had to learn to live with earthquakes.

Since the early fall, there have been thousands, none of them very large — a fraction have been felt, and the only documented damage is a cracked window in the snack bar at Woolly Hollow State Park. But in their sheer numbers, they have been relentless, creating a phenomenon that has come to be called the Guy earthquake swarm.

This was followed by the Guy media swarm, with reporters pouring in through the surrounding orchards and cow pastures to ask residents what the quakes feel like.

Mr. DeTurck and many others described a boom followed by a quick, alarming shift, a sensation one man compared to watching the camera dive off a cliff in an Imax movie. Some say they have felt dozens, others only four or five, and still others say they have only heard them.

They do, however, have similar suspicions about the cause.

Several years ago, the gas companies arrived, part of a sort of rush in Arkansas to drill for gas in a geological formation called the Fayetteville shale.

Local landowners signed leases and royalty agreements with the companies on the promise of a few hundred dollars or more a month. Drilling sites started showing up in the fields, and the trucks began rumbling through day and night. Residents began to wonder whether all of this was such a good idea.

“They took advantage of people’s ignorance,” said Greg Hooten, the superintendent of the local water utility, who now worries about the effect of the drilling on the groundwater. Nonetheless, Mr. Hooten had signed an agreement for drilling on his property. “Who’s going to stop the gas and oil companies?” he asked.

The companies are engaging in hydraulic fracturing, whereby water, sand and chemicals are injected at high pressures into underground formations to open pockets of gas. Much of the watery mix that is injected into wells comes back out as waste, and something has to be done with it.

Disposal wells are dug, and the wastewater is injected deep into the earth. Last summer a few of these injection wells appeared near the town, including the one across from Big Pop’s fruit stand, just past the school.

Then the ground started shaking.

There are two important facts about the Guy swarm. The first is that such swarms have happened around here twice in the past three decades, long before the gas companies came.

The Enola swarm in the early 1980s occurred about 10 miles to the southeast. Over a comparable six month period, 550 locatable earthquake events occurred in the Enola swarm, compared to 640 around Guy. In both cases, thousands of smaller quakes were recorded by seismographs.

The largest back then measured a magnitude 4.5; the largest this time has measured 4.0.

Though the exact causes are unknown, the Enola swarm and another similar swarm in the area in 2001 are considered natural occurrences. (They also do not appear to be related to the major New Madrid Seismic Zone, which reaches into the state’s northeastern corner.)

But researchers with the Arkansas Geological Survey say that while there is no discernible link between earthquakes and gas production, there is “strong temporal and spatial” evidence for a relationship between these quakes and the injection wells.

For decades, scientists have been researching induced seismicity, or how human activity can cause earthquakes. Such a link gained attention in the early 1960s, when hundreds of quakes were recorded in Colorado a few years after the Army began injecting fluid into a disposal well near the Rocky Mountain Arsenal.

So last year, when earthquakes were recorded in small, discrete clusters in north central Arkansas, researchers perked up. Knowing that there would be two new active injection wells around Guy, they set up a network of measuring stations in the area last summer.

Sitting in the lobby of the Oil and Gas Commission office in Fort Smith, just a few hours before Mr. DeTurck would have his meeting, Scott Ausbrooks, a geologist with the Arkansas Geological Survey, pulled up a slide on his laptop. The screen was crossed by squiggly lines in an imitation of a seismograph. There were scores of blips, some small, others hysterical.

“All this activity happened after these wells had gone online,” Mr. Ausbrooks said.

Then he pointed to a map, where the quakes were represented by colored dots. The injection wells appeared almost as small doses of fertilizer, surrounded by a fruitful and colorful bloom.

Gas company representatives are skeptical.

“We’ve found no causal connection,” said Charles Morgan, a lawyer representing Poseidon Energy Services, which has a proposed injection well in limbo under a state-imposed moratorium. “The evidence is anecdotal at best.”

Mr. Ausbrooks said the fact that swarms had naturally happened here did not necessarily discount a link.

“What you could be looking at is a case where the strain was already there,” he said. “You’d be fast-forwarding the clock.”

There has not been a quake measuring over magnitude 3.1 recorded since early December, but researchers are studying whether the ebb and flow of the quakes match that of the activity at the injection wells.

Mr. Ausbrooks and his colleagues were in Fort Smith to present their data to the staid men of the commission, who were considering an extension of the one-month moratorium on new disposal wells in about 600 square miles around Guy (the seven existing wells in the area remain active, though the gas companies are required to submit regular operational reports).

Citing a need for further research, the commission voted for a six-month extension of the moratorium without hearing the presentation or facing much of a fight from the gas company lawyers.

And so the people of Guy, like Betty Baker, 73, will continue to ride out the swarm. Ms. Baker, one of the handful of concerned residents at Mr. DeTurck’s meeting, said she had never felt the quakes, though her dog Teddy seemed to jump on the bed at odd moments. She had, however, heard the booms.

“But I live near a machine shop, so I’m not sure if it’s there,” she added. “That machine shop does make a lot of racket.”

www.nytimes.com/2011/02/06/us/06earthquake.html

Feb. 5, 2011