Fractivists celebrated at the tail end of November as Massachusetts lawmakers advanced a 10-year state ban on hydraulic fracing from one committee to another. The Massachusetts bill came “as a wave of earthquakes in Texas has raised new concerns over the controversial drilling technique,” one widely distributed article reported.

The state could join Vermont as the nation's second no-frac zone. Still, the legislation is a swing and a miss at oil and gas companies. Oil and gas operators appear uninterested in Massachusetts and no driller has applied for an oil or gas permit, according to the Massachusetts Geological Society. The state's geology makes drilling uneconomic.

But the timing of the bill's passage was just right for fracing foes. November brought a series of earthquakes to North Texas' Fort Worth Basin. Several activists and articles connected the events and cited the ban as protection from the devastation fracing can inflict.

Seismologists have a different take on the connection between hydraulic fracturing and earthquakes. “There's no relationship between hydraulic fracturing and the events we have seen,” said seismology professor Brian Stump, a researcher at Southern Methodist University. Stump recently published a study on seismic activity near Cleburne, Texas.

However, Stump said wastewater injection wells could be culprits, though there is no “definitive evidence” yet.

In November, the US Geological Survey recorded 23 earthquakes in North Texas around the same few towns. The seismic vibrations registered a median of 2.8 on the Richter scale with the strongest at 3.6. Quakes below 4.0 are generally regarded as light and above 4.0 as minor.

“These in general are pretty small earthquakes,” Stump said. “It's probably when you get above four that you begin to see a little bit of impact.” Likewise, research by Cliff Frohlich, a seismologist at the University of Texas at Austin's Institute for Geophysics, found that most Texans consider earthquakes rare, annoying and an excuse for “excessive regulation.”

Texas Railroad Commission records on more than 100,000 producing oil and gas wells and tens of thousands of injection wells have yielded “probably fewer than 20 fields where induced earthquakes may occur,” he said.

Mark Zoback, a Stanford geophysics professor, said in a university publication that some seismic activity does occur during fracing, but it's too small to be felt.

“The energy released by one of these tiny microseismic events is equivalent to the energy of a gallon of milk hitting the floor after falling off a kitchen counter,” Zoback says. “Needless to say, these events pose no danger to the public.”

But for seismologists, that begs the question of whether disposal of wastewater in wells might be a cause. Across the US, increased seismicity has been observed in Oklahoma, Ohio and Arkansas, Stump said.

“I'm struck by the broad increase in seismicity across the Fort Worth Basin in an area where historically we don't have a record of events like these,” he said. “That makes me wary that there might be a linkage, and that it very much needs to be considered and studied.”

Still, he could not make a link in his own study of 2009 Cleburne earthquakes. The first felt quake occurred in June of that year, but wastewater injection started in 2005 at a northern well and in 2007 at a southern well.

Further, in 2010, injection at the well closer to the earthquake locations continued with modestly increased fluid volumes, but no more events were felt.

However, Stump said a link between injection wells and earthquakes is possible.

In Cleburne, Stump identified a nearby fault line about a kilometer long (.62 mile). Among the questions he has: How did fluids travel to a fault from an injection site more than half a mile away?

Frohlich's 2012 two-year survey of seismicity within the Barnett shale found numerous earthquakes occurring near injection wells.

The survey found that quakes only occurred near wells where maximum injection volumes exceeded a critical rate of 150,000 barrels of water per minute.

Still, in an August interview in the San Antonio Express - News, Frohlich said he had a nuanced view of earthquakes in the Eagle Ford and elsewhere.

“I don't think people should be hugely concerned, because of the huge amount of production and injection we've had in Texas,” he said. “If it were a big problem, Texas would be famous for all its earthquakes.”