"Induced" Earthquakes Have Increased Dallas' Risk, USGS Says

The U.S. Geological Survey's 2016 earthquake map.EXPAND
The U.S. Geological Survey's 2016 earthquake map.
U.S. Geological Survey

Just looking at the map is striking. According to new data released by the U.S. Geological Survey, human activity is causing earthquake risk in areas that previously had basically no risk for seismic activity. The survey's new 2016 map shows natural risk, which for the most part cuts off just west of Denver,  and, for the first time, "induced" or man-made earthquake risk.

“By including human-induced events, our assessment of earthquake hazards has significantly increased in parts of the U.S.,” Mark Petersen, chief of the USGS National Seismic Hazard Mapping Project said in announcing the new map Monday. “This research also shows that much more of the nation faces a significant chance of having damaging earthquakes over the next year, whether natural or human-induced.”

The risk for man-made earthquakes, according to the USGS, pops up across the country, including in many areas that are home to fracking and the high-pressure, underground disposal of wastewater from drilling, like North Texas. Previous risk maps showed DFW having no significant earthquake risk. Now, North Texas cities have a between 1 and 5 percent chance of being significantly affected by an earthquake. Texas, the USGS says, has the sixth-highest hazard level in the country for man-created earthquake activity.

A USGS map of areas with increased seismic activity over the last 25 years.
A USGS map of areas with increased seismic activity over the last 25 years.
United States Geological Survey

According to Earthquake Track, only two perceptible earthquakes have rattled North Texas so far in 2016. Over the last 12 months, however, there have been 52. The Texas Railroad Commission, the state body that controls the issuing of permits for both fracking and wastewater wells, gave the Observer the following statement when asked for comment about the new USGS map: 

The Railroad Commission’s regulatory decisions are made based on science, data and best practices to ensure protection of public safety and our natural resources. The Commission has some of the most stringent seismicity rules in the nation. Since the Commission’s seismicity disposal well rules went into effect Nov. 17, 2014 through March 8, 2016, the Railroad Commission has received 47 disposal well applications in areas of historic seismicity. Of these, 20 permits have been issued with special conditions, such as requirements to reduce maximum daily injection volumes and pressure and/or to record volumes and pressures daily as opposed to monthly. Nine applications were returned or withdrawn. Three applications were protested and sent to hearing. Nine permits were issued without special conditions, and six applications are pending.

With regard to the seismic activity in the Azle area, the Commission held show cause hearings requiring disposal well operators in the area to provide evidence they were not responsible for contributing to seismicity. As a result of those highly technical, scientific hearings, it was determined they were not.

Additionally, the Railroad Commission is looking forward to the implementation of the TexNet system to help gain a better understanding of natural and induced seismicity in Texas. The Commission’s seismologist will be working closely with the TexNet team on this important program.

Azle and Reno, both located west of Fort Worth in Tarrant County, experienced a swarm of earthquakes from November 2013 until January 2014. A Southern Methodist University research team found that the quakes were likely the result of induced seismicity, the very thing the USGS has identified as a risk, caused by wastewater injection activities in the area. As alluded to in the statement, the railroad commission rejected that argument.


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