Northern Texas towns are experiencing an intense string of earthquakes – the last of which was one of the most powerful in 5 years. As unusual tremors have been going on for over 3 weeks now, many suspect fracking might be to blame.

On Thursday, the region experienced two tremors, with one of them registering 3.6 magnitude, 55 km west of the town of Azle at 07:58:36 GMT, as recorded by the US Geological Service, and the other 2.8 at 08:41:07 GMT, with the epicenter not far from the first one. USGS records show that the 3.6 tremor was one of the strongest earthquakes to hit the region in 5 years.

“It sounded like a sonic boom, and then the house started shaking,” Keith Krayer, a local resident who felt the effects of the quake, told RT.

Krayer said he had no doubt the quake was sparked by fracking. “When they frack, they inject all that water and chemicals into the ground, then they pump it back up and separate the gas from the water, then they have to dispose of that water 13,000 feet down. It causes the plates to slip, the lubrication from the water.”

Residents like Krayer are having their nerves put to the test as the region chalked up its 16th this month. In the last four days, there have been six recorded quakes.

Between 1970 and 2007, the area around the Texas town of Azle (pop. 10,000) experienced just two earthquakes. The peace and quiet began to change, however, at the start of 2008, when 74 minor quakes were reported in the region.

Now an increasing number of people, including scientists, are speculating that natural gas production by fracking - a process that forces high pressure water and chemicals into rock in order to extract natural gas reserves - is the culprit. The problem, however, is proving the claims.

Cliff Frolich, earthquake researcher at the University of Texas, said waste water injection wells from fracking could be responsible for the recent spate of earthquake activity.

"I'd say it certainly looks very possible that the earthquakes are related to injection wells," he said in an interview with KHOU television.

Frolich left room for doubt when he said thousands of such wells have operated in Texas for decades with no quakes anywhere near them.

Frolich co-authored a 2009 study on earthquake activity near Cleburne, just south of Azle, which concluded: "The possibility exists that earthquakes may be related to fluid injection."

A recent government study lent credence to Frolich’s findings.

The use of underground storage wells to get rid of waste water produced by fracking is “almost certainly” to blame for the jump in earthquakes in Midwestern states in recent years, a recent Geological Survey study has found.

The report said the number of magnitude-3 earthquakes or greater occurring in the mid-region of North America surged from 29 in 2008 to 134 last year.

The USGS study pointed to an unusual surge in tremors near wastewater wells in many US states, including Arkansas, Colorado, Texas, Oklahoma and Ohio.

However, the USGS stopped short of linking the process of fracking to earthquakes directly, mostly blaming methods used to dispose of fracking by-products.

In January 2012, following a rash of earthquakes, including a 4.0-magnitude tremor, Ohio legislators placed a temporary ban on fracking after experts said the controversial process for storing waste water in deep underground wells was to blame for the outbreak of tremors.

Meanwhile, the mayor of Azle, Alan Brundrett, said it's crucial to determine whether the latest series of quakes are man-made.

"What could it cause down the road?" he asked. "What if a 5.0 happens and people's houses start falling in on them?"

"Enough is enough!" Keith Krayer, a resident of Briar, just north of Azle was quoted by the station as saying. "My wife, she's having panic attacks because of it."

Thus far, the rattling has just produced a lot of anxiety. The Parker County Sheriff's Office has no reports of damage or injuries from any of Thursday’s earthquakes.

As of March 2012, Texas had listed nearly 6,000 oil and gas fracking wells on FracFocus, an industry fracking disclosure site, SourceWatch.org reports.

The first instance of hydraulic fracturing – creating fractures from a wellbore drilled into reservoir rock formations – was reportedly performed in 1947, the organization notes. Fracking on a commercial scale, however, was first used in the Barnett Shale – a geological formation which underlies the city of Fort Worth and at least 17 counties.

The first Barnett Shale well was completed in 1981 in Wise County, Texas. Subsequent drilling expanded greatly in the early 2000s due to a hike in natural gas prices and the use of horizontal wells to increase production.

Fracking and horizontal drilling technology have been heralded as an economic boon by the oil industry, though the techniques have contributed to nationwide concern about air pollution, groundwater contamination and broader environmental degradation.

The month that rocked

November 6 (2)

2.6 tremor near Reno (7:32 AM)

2.7 tremor near Springfield (9:05 PM)

November 8

2.9 tremor near Springtown (8:32 AM)

November 9

3.0 tremor near Springfield (11:54 PM)

November 11

2.8 tremor near Briar (12:30 PM)

November 13

2.6 tremor near Eagle Mountain (1:01 PM)

November 19 (2)

2.5 tremor near Reno (9:57PM)

2.8 tremor near Azle (10:03 PM)

November 20

3.6 tremor near Azle (4:40 AM)

November 23

2.9 tremor near Reno (1:43 PM)

November 25

3.3 tremor near Azle (11:43AM)

November 26 (2)

2.7 tremor near Reno (5:55 AM)

3.0 tremor near Azle (6:24 PM)

November 27

2.8 tremor near Springtown (3:28 AM)

November 28 (2)

3.6 tremor near Mineral Wells (11:58 PM)

2.8 tremor near Jacksboro (12:41 PM)