A series of earthquakes that rattled a small Texan community have been linked to nearby oil and gas operations . In 84 days from November 2013 to January 2014 , the area around Azle , Texas , shook with 27 magnitude two or greater earthquakes . Now scientists believe these earthquakes were the result of high-pressure injection of drilling wastewater into the ground . A series of earthquakes that rattled a small Texan community have been linked to nearby oil and gas operations . In this image red squares are injector locations ; pink arrows , approximate location of two large brine production wells that are located both near the faults and near reported earthquakes swarms . The oil and gas industry uses injection wells to get rid of wastewater , which can have chemicals , heavy metals , salt and radioactive material . The scientists determined this based on where and when the earthquakes happened ; computer models that track pressure changes ; and company data from nearby wells . Matthew Hornbach , a Southern Methodist University geophysicist , said the timing and location of the quakes correlates better to the drilling and injection than any other possible reason . 'There appears to be little doubt about the conclusion that the earthquakes were in fact induced , ' USGS seismologist Susan Hough , who was n't part of the study team , said in an email . 'There 's almost an abundance of smoking guns in this case . ' This adds to other studies that linked injecting wastewater from energy wells to a tremendous jump in earthquakes in Oklahoma and southern Kansas . The map shows inferred faults ( dashed ) at the top of the Blenburger formation , injection wells ( red squares ) , two production wells ( API 36734045 and 36734139 ) with significant brine production near the faults ( pink arrows ) and earthquake epicentres ( coloured circles ) recorded by the temporary seismic network ( triangles ) In these areas , there have been more than 950 magnitude 2 or higher quakes so far this year , according to the USGS . Earlier today , the Oklahoma Geological Society said it is 'very likely ' that most of the earthquakes that have shaken the state in recent years have been triggered by the subsurface injection of wastewater from oil and natural gas drilling operations . The society released a statement following an investigation into dozens of earthquakes recorded in central and north-central Oklahoma . The fluid pressure in the pores and fractures of the rocks is called the 'pore pressure . ' The pore pressure acts against the weight of the rock and the forces holding the rock together . If the pore pressures are low - especially compared to the forces holding the rock together - then only the imbalance of natural in situ earth stresses will cause an occasional earthquake . If , however , pore pressures increase , then it would take less of an imbalance of in situ stresses to cause an earthquake . This type of failure is called shear failure . Injecting fluids into the subsurface is one way of increasing the pore pressure and causing faults and fractures to 'fail ' more easily . Earthquakes can be caused by injecting fluid into the subsurface or by extracting fluids at a rate that causes subsidence and slippage along planes of weakness in the Earth . Source : US Department of Energy . Unlike other research that linked quakes to the injection of wastewater , the SMU study also sees a secondary link in another part of the drilling process . Massive amounts of brine taken out of the ground with the gas , said study co-author William Ellsworth of the USGS . Removing the saltwater changes the underground pressure . But the deep injection of the wastes still is the principle culprit , Ellsworth said . Azle sits atop the large underground Barrett Shale natural gas formation . The findings come amid heightened debate over oil and gas regulations , including efforts in some communities to ban drilling . Earthquakes can be caused by injecting fluid into the subsurface or by extracting fluids at a rate that causes subsidence and slippage along planes of weakness in the Earth . This infograpic shows the natural and man-made stress changes that may trigger earthquakes in Azle . In Texas , lawmakers are considering bills that would limit cities ' abilities to do so . 'Cities across the state should be very , very worried , ' Sharon Wilson , an organiser based in Dallas for the environmental group Earthworks , said in a statement . 'It is only Texas state regulators and lawmakers who are living in denial . ' The Texas Railroad Commission , the state 's oil and gas regulator , hired its first seismologist last year to investigate potential links between quakes and fracking after Azle residents asked the agency to halt oil and gas activities . The seismologist has not offered any conclusions . Remi Oldham , an SMU geophysics graduate student , runs a cable to connect the seismometer to communications interface equipment housed in the orange metal box in Willow Park , Texas . The interface equipment allows the transmission of the data collected by the seismometer back to SMU . Azle is a city located in Tarrant County in Texas . It sits atop the large Barrett Shale natural gas formation .
Azle has recently been shaken by two quakes with magnitude 27 or greater . Scientists say this is the result of injecting wastewater into the ground . This increases pore pressure in the rock causing faults to 'fail ' more easily .