Beginning the first part of November 2013, the Azle area (Tarrant/Parker counties) experienced over 20 earthquakes. Although they were minor in size, their presence was felt. This series of quakes seemed to come out of nowhere; and since the Azle area did not have a history of earthquakes, it was understandable the residents living in the “quake zone” were concerned.
So what was done?
City Staff contacted geologists and state and federal officials to see if a determination could be made as to why this sudden appearance of earthquakes in the Azle area. U.S. Geological Survey (USGS) officials worked with researchers at Southern Methodist University to position digital seismographs in the Azle area to help pinpoint more accurate locations for the epicenters of the quakes since the closest monitoring instrument was about 60 miles away. In December 2013, the USGS filed a preliminary report (PDF) on the recent earthquake activity near Azle.
In February 2014, SMU seismologists established a web page to provide information regarding their ongoing study of the earthquake sequences in the Azle-Reno area, the installation of seismic equipment and answers to some frequently asked questions.
In March 2014, Texas Railroad Commission hired a seismologist, Dr. David Craig Pearson, a former team leader for a Los Alamos National Laboratory seismic, experimental field team, who also holds a doctorate in geophysics from Southern Methodist University, to further examine any possible correlation between seismic events and oil and gas activity and gain a more thorough understanding of the science and data available.
Press Release - RRC Hires Seismologist (PDF)
In May 2014, the chairman of the Texas House Committee on Energy Resources created the Subcommittee on Seismic Activity to investigate the recent increased seismic activity that was occurring in areas adjacent to oil and gas production and disposal wells. The Subcommittee was chaired by the Vice Chair of Energy Resources Myra Crownover (R-Denton) and included Representatives Phil King (R-Weatherford ), Terry Canales (D-Edinburg), and Chris Paddie (R-Marshall). The committee was charged with studying the conditions surrounding the increased seismic activity in the Barnett Shale and other areas of the State. Specifically, review the possibility that increased exploration and disposal well activity could impact seismic activity.
In October 2014, the Texas Railroad Commission unanimously adopted disposal well rule amendments designed to address disposal well operations in areas of historical or future seismic activity. Disposal wells are permitted by the Railroad Commission to safely dispose of non-hazardous produced water (saltwater) and hydraulic fracture flowback fluid from oil and gas wells. The adopted rule amendments became effective November 17, 2014.
Press Release - Rule Amendments
In April 2015, an SMU-led seismology team found that high volumes of wastewater injection combined with saltwater (brine) extraction from natural gas wells was the most likely the cause of earthquakes occurring near Azle, Texas, from late 2013 through spring 2014.
Read the Report