More than 30 earthquakes jolted the area in and around the City of Azle, Texas - 20 miles north of Fort Worth - last November through January. In response to citizen concerns, the Texas House Committee on Energy Resources created a Subcommittee on Seismic Activity, to investigate whether there was a link between earthquakes and increased oil and gas production and disposal wells. On August 12, the Railroad Commission of Texas, with support from both the Texas oil and gas industry and environmental groups, proposed rules that would require companies to do a seismic survey before obtaining permits for new oil and gas disposal wells - so-called Class II injection wells. On October 28, 2014, the Railroad Commission unanimously voted to finalize that proposal.

Presently, the state has more than 3,600 active commercial injection wells used for the disposal of oil and gas wastes. The rules require applicants for new oil and gas disposal wells to provide additional information, including logs, geologic cross-sections, and structure maps for injection wells in an area where conditions exist that may increase the risk that fluids will not be confined to the injection interval. Those conditions include, among other things, complex geology, proximity of the base rock to the injection interval, transmissive faults, and a history of seismic events in the area as demonstrated by information available from the USGS. The rules also clarify that the Railroad Commission may modify, suspend, or terminate a permit if fluids are not confined to the injection interval, that is, if it poses a risk of seismic activity. The effect of these rules will be not only to regulate oil and gas disposal activities to address potential seismic effects, but also to generate data that may be useful in determining whether and to what extent to further regulate those activities. The rules also may serve as a model for other states concerned about the seismic effects of oil and gas waste disposal.