The research is in the form of a computer model and field experiment data of ground faults. The combined approach indicates that there is a connection between subsurface fluid injections and earthquake swarms, this is rapidly spreading earthquake activity well-beyond the fluid diffusion zone. Where fracking occurs, the data indicates that the frequency of human-made earthquakes surpass natural earthquake hotspots.
The practice of subsurface fluid injection is commonly used in both ‘fracking’ (hydraulic fracturing) and wastewater disposal for oil and gas exploration. Fracking is a controversial activity. In the U.S., from an economic perspective, fracking has boosted domestic oil production and driven down gas prices; however, fracking uses huge amounts of water and the practice can be associated with the causing ground tremors.
While it is established that deep fluid injections (deep meaning below one kilometer deep) are connected with enhanced seismic activity, it was thought that these tremors were limited to the areas of fluid diffusion. The new research from Tufts University shows that this confined is most likely mistaken. The researchers have found that fluid injections are causing significant earthquakes further afield. This is occurring due to the interconnections between pre-existing fault fracture networks, where shock waves are transferred in a domino-like fashion.
The findings are significant in that, while most earthquakes associated with fracking are very small along the Richter scale, the practice of deep injection appears to be affecting deeper and larger faults that are under stress and susceptible to fluid induced slippage. Where such faults occur the injection of wastewater can lead to earthquakes that are large enough to potentially cause damage.
By pulling together various strands of data, like fault pressurization and displacement, slippage and other parameters, the researchers have developed a new model to evaluate the effects of fracking in a given geographical area. The data used for the model related to the U.S.
According to one of the researchers, Pathikrit Bhattacharya: “These results demonstrate that, when available, such observations can provide remarkable insight into the mechanical behavior of faults and force us to rethink their hazard potential.”
The research is published in the journal Science, with the peer-reviewed research paper titled “Fluid-induced aseismic fault slip outpaces pore-fluid migration.”
