More than six months after a series of earthquakes surprised parts of North Texas, the mayors of two shaken-up towns say that the state has moved too slowly in investigating what’s behind the phenomenon and whether local oil and gas activities are to blame.

“If I could sum up our experience in one word, it would be frustration,” Azle Mayor Alan Brundrett said Monday at the first meeting of the Texas House Subcommittee on Seismic Activity. “While everyone seemed genuinely concerned, there is a disconnect between various stakeholders.”

Lynda Stokes, mayor of neighboring Reno, said her town’s major concerns are "getting lost in politics.”

“The industry’s right to profit does not surpass our right as citizens to the quality of life we’ve come to know,” she said.

Led by state Rep. Myra Crownover, R-Denton, the subcommittee is tasked with investigating any possible links between the state’s booming oil and gas industry and a recent uptick in earthquakes — particularly in North Texas’ Barnett Shale region, which is pockmarked with natural gas wells and injection wells used to dispose of drilling waste injected at high pressure thousands of feet below the surface. The area has seen heavy drilling since the mid-2000s.

Crownover and other lawmakers at the three-hour hearing spent most of their time asking questions. State Rep. Phil King, R-Weatherford, however, suggested that the Texas Railroad Commission, the state's oil and gas regulator, become a clearinghouse for still-needed information and be “the driving force that pulls everyone together.”

Since Nov. 1, according to U.S. Geological Survey data, at least 27 mild earthquakes have struck near the border of Parker and Tarrant counties in and around Azle and Reno.

The frequency of those earthquakes, whose magnitudes ranged from 2.1 to 3.7, have decreased in recent months, but the mayors said that local residents, including some who blame the tremblors for busted water pipes and cracked home foundations, are no less concerned.

Texas lawmakers, regulators and university researchers have helped the mayors gather information on disposal wells and earthquakes, but no one has pulled all the data together, and many pieces are missing.

“We have a state agency that has the authority to regulate those operators, yet we can’t get everyone together to share the information we need to address the problem,” said Brundrett, whose local school districts now regularly conduct earthquake drills, a practice unheard of in years past. “It’s time to step up and confirm – once and for all – whether disposal wells are causing these quakes and why.”

The Railroad Commission has not linked the injection wells and earthquakes, saying it says it needs more scientific proof. In April, the commission hired a seismologist to investigate any industry ties. Last week, it sent letters to seven operators of disposal wells near in the affected area asking for daily logs of injection volume and pressure, David Craig Pearson, the commission's new seismologist, testified.

Researchers at Southern Methodist University say they are working to map the tectonic plates deep underground, but they cannot pinpoint how injected waste migrates and interacts with the plates without knowing the volumes and pressures at which it is injected at each well. Well operators report that data to the Railroad Commission. The data, however, is aggregated on a monthly basis, and the information is not publicly available for months after it is collected.

The most recent available data on pressure and volume dates to October 2013, shortly before the spate of earthquakes began.

“This is a problem that’s going to take a number of people to try to bring those people together,” Brian Stump, an SMU seismologist, testified.

In December 2013, SMU’s research team added 12 seismometers — instruments that detect and measure earthquakes — to the Reno-Azle area to get more accurate readings than the few U.S. Geological Survey monitors can give. The new equipment has detected more than 300 tremors large enough to be recorded, most of them tiny.

Scientists have known for decades that injecting fluid deep underground could trigger earthquakes. Oklahoma has seen an increase in earthquakes even greater than Texas has. That state saw 183 earthquakes of magnitude 3.0 from October 2013 through April 14, 2014, according to the USGS. That compared with an average of just two per year the previous three decades. The USGS and Oklahoma Geological Survey say wastewater disposal probably contributes to the trend.

Though Texas, home to nearly 3,600 active disposal wells, is four times the size of Oklahoma, it has far fewer seismometers positioned throughout the state. That makes it difficult to estimate the precise size and locations of each quake and, in turn, understand what caused it.

Though rare, North Texas' recent cluster of earthquakes was not the first to startle the region.

In 2008 and 2009, the Dallas-Fort Worth area was shaken by three series of earthquakes, with magnitudes as high as 3.3. In a study prompted by those concerns, researchers at Southern Methodist University and the University of Texas at Austin concluded that local disposal wells were a “plausible" cause, though they found it “puzzling” that the tremors were concentrated in just one or two locations in a region that had more than 200 disposal wells. Before 2008, that region had one recorded earthquake above a magnitude of 2.0. Since then, more than 70 such earthquakes have been recorded.

Ohio recently tightened its rules for waste disposal and production wells in an attempt to rein in earthquakes. In March, Ohio regulators shut down waste disposal sites near Youngstown after a series of quakes, though they said they had ruled out injection wells as the cause. In April, the state's environmental regulators unveiled new policies that require companies to install seismometers when drilling horizontally near faults or in certain seismic areas. If those monitors detect quakes above a 1.0 magnitude, activity must stop while the cause is investigated.

Milton Rister, executive director of the Railroad Commission, said the agency is “definitively paying attention” to the earthquakes, but “we recognize that we have to move cautiously, and a knee-jerk reaction could have a damaging impact on Texas’ economy.”

Rister said the agency might eventually tweak regulations for disposal wells, but he said he could not provide details on how that might look.

King said he understands his constituents' frustrations with the speed of Texas' earthquake investigations, but compared with how state bureaucracy can be at times, he said, the speed of the current investigations is "really fast."

Disclosure: The University of Texas at Austin is a corporate sponsor of The Texas Tribune. Southern Methodist University was a corporate sponsor of the Tribune in 2013. A complete list of Texas Tribune donors and sponsors can be viewed here.