The shaking around Azle and Reno, which I will hereafter refer to as "San Andreas Minor," has attracted the attention of the U.S. Geological Survey precisely because the area has almost no record of seismic activity. A few studies, including one recently from SMU, point to correlation between the epicenter of the earthquake swarms and the locations of underground injection wells for fracking wastewater.
However, there isn't enough granular, on-site seismic data to draw hard conclusions yet. It's thought that the injection alters the bedrock stresses on faulting in this area, inducing slippages that produce quakes like the magnitude 3.6 detected in near Azle just a few days ago. The USGS says this is entirely possible, but to arrive at that degree of certainty, it needs more data, which is why it just lent SMU four seismic monitors to be positioned in private homes, public buildings and schools in the area.
Another entity with an intimidating acronym, Program for Array Seismic Studies of the Continental Lithosphere (PASSCAL), will provide some 15 sensors to the effort. "We are first going to focus in on where the earthquakes have been occurring -- about a five- to six-mile area near Reno and Azle," said Heather DeShon, SMU associate professor of geophysics. "How long the monitors remain depends on continued seismicity. We're thinking a few months."More »