The increasingly common practice of disposing of oil and gas drilling wastewater by injecting it underground can trigger earthquakes, according to federal scientists who studied quakes since 1970 in Colorado and neighboring states.

Colorado authorities on Monday said they are aware of concerns about the earthquakes but questioned the U.S. Geological Survey study, saying more research needs to be done. Nonetheless, Colorado officials have been reviewing company permits to assess seismic risk since a 5.3-magnitude earthquake near Trinidad last year.

Some 330 fracking wastewater disposal wells have been drilled around Colorado. Drilling companies inject huge volumes of the brine water and chemical waste generated by hydraulic fracturing.

“This is a societal risk you need to be considering,” said U.S. Geological Survey scientist Justin Rubinstein, co-author of a report to be presented this week at an American Geophysical Union gathering.

A USGS team based in Menlo Park, Calif., found that the quake in Colorado and a damaging 5.6-magnitude quake in Oklahoma both were induced by disposal of fracking waste underground.

The team focused on the Raton Basin of northern New Mexico and southern Colorado where, from 1970 until 2001, five quakes of magnitude 3 or higher were recorded. They counted 95 quakes of that magnitude between 2001 and 2011, and concluded that oil and gas operations caused the majority, if not all, of the quakes since 2001.

While the evidence is convincing that deep burial of drilling waste can trigger quakes, it also appears that few of the 40,000 disposal wells nationwide have done so, Rubinstein said.

“But I don’t think blowing this off is a good idea,” he said. “It’s a problem we need to understand. There’s been millions of dollars of damage. If you trigger bigger earthquakes, there’s a possibility of worse outcomes.”

Burying fracking waste is becoming more common as the natural gas industry expands. And it has been considered a more environmentally friendly practice than dumping it in rivers.

Colorado’s Oil and Gas Conservation Commission, the body charged with simultaneously regulating and promoting the industry, asked state geologists last year to review all permits for new disposal wells to assess earthquake risk, Colorado Geologic Survey chief Vince Matthews said.

Of the 330 or so disposal wells, 35 have been analyzed. Geologists recommended that COGCC tell some operators that, if any small quakes are detected, the operators should pay close attention and install additional seismic sensors, Matthews said.

State criteria include whether quakes have happened before near a well, fault lines in the area and the direction of cracks in rock.

The federal scientists may be jumping to conclusions, Matthews said. Companies including Texas-based Pioneer Natural Resources are using seismometers in wells to gather data for the state that is more precise than the federal data the USGS scientists used, he said.

“I don’t think they’re nuts. I just think it is premature,” he said. “We’re gathering data that is going to help us understand what is going on down there.”

The USGS study went through an internal administrative review before this week’s unveiling. No peer review has been done.

Federal scientists discovered that most quakes this past decade were located within 3 miles of active disposal wells. They noted that wells contained exceptionally large volumes of wastewater.

The Colorado quake in August 2011, for instance, followed injection of 4.9 million cubic meters of wastewater, more than seven times as much as was injected in Denver at the Rocky Mountain Arsenal in the 1960s — a classic case of earthquakes induced by industrial activity.

State officials charged with overseeing the oil and gas industry “haven’t done their own, independent research on this. If they can demonstrate that we are incorrect, we’re happy to have that conversation,” Rubinstein said. “At the moment, we’re the only people who have done this work, and our evidence is pretty conclusive.”

Bruce Finley: 303-954-1700, twitter.com/finleybruce or bfinley@denverpost.com