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Post Christchurch-2011 earthquake, there was much concern that fracking in the surrounding areas might lead to further quakes, as was rumoured to have happened elsewhere in the world.
Is there evidence that fundamentally validates or discredits this?
It's not too too likely, but it can happen. A few earthquakes have either been attributed to fracking, or the wastewater produced from fracking.
According to the USGS (for more information, visit that page):
Many questions have been raised about whether hydraulic fracturing — commonly known as “fracking”— is responsible for the recent increase of earthquakes. USGS’s studies suggest that the actual hydraulic fracturing process is only very rarely the direct cause of felt earthquakes. While hydraulic fracturing works by making thousands of extremely small “microearthquakes,” they are, with just a few exceptions, too small to be felt; none have been large enough to cause structural damage. As noted previously, underground disposal of wastewater co-produced with oil and gas, enabled by hydraulic fracturing operations, has been linked to induced earthquakes.
So, indeed, the disposal of wastewater has been linked to earthquakes.
This study in Geology also came to the same conclusion that the wastewater of fracking caused earthquakes.
An additional study produced by Ohio geologists concluded that a few small earthquakes were due to fracking. I do wonder exactly what they concluded, but the news story doesn't say. It does say this, but it doesn't say exact what this study was, either:
A U.S. government-funded report released in 2012 found that two worldwide instances of shaking can be attributed to actual extraction of oil and gas, as opposed to wastewater disposal in the ground — a magnitude-2.8 quake in Oklahoma and a magnitude-2.3 quake in England. Both were in 2011.
Your question uses the word "likely", so to that I would say no, it's not likely, but it can happen, depending on the tectonic setting and the state of the stress field.
In 2007 work on the "hot rock" geothermal project in Basel, Switzerland was stopped because hydraulic stimulation caused a series of small seismic events that were over a predetermined safe level of magnitude. Most of the seismic events were too small to be felt at the surface, or even recorded on "normal" seismometers. The project was located in an active fault setting, and in the centre of a city, and though the seismic activity was at most about 3 ML (Richter scale), the project was deemed unsafe for the city's residents and buildings and eventually canned.
Some large dams are known to cause minor seismic activity as they fill up, again depending on the tectonic setting.
I suggest that all the relatively small earthquakes in Oklahoma that have done minor damage are the result of fracking. I don't know much about earthquake history in Oklahoma but I would not expect the center of the continent to be that active (Cairo, Illinois area being an exception)
