The entire study is false. There's no fracking reference.
That is what we're told in Oklahoma/Kansas. We have hordes of believing Borg Drones that will recite on command Earthquake=Fracking.
(No global warming reference, either.)
The Borg Drones have their frac jobs confused with injection wells.
The Youngstown, Ohio quakes were caused by wastewater injection wells, not fracking itself, but the disposal of produced water from wells that had been hydraulically fractured. Oil and gas production has produced water associated with the oil and gas. That water is commonly disposed of in wastewater injection wells, and, depending on where those wells are sited, there can be problems with injecting the wastewater from dozens of wells at one site.
http://www.huffingtonpost.com/2013/09/04/youngstown-ohio-earthquakes-wastewater_n_3869286.htmlThese aren't the sort of rocks you'd frac.
I had an Igneous and Metamorphic Petrology professor who predicted the discovery of stratified rock in the crystalline piedmont of the Appalachians before seismic studies confirmed it. (not counting the Triassic rift basins). Considering the Catoctin meta basalt may have been obducted onto the craton and not just rift associated, the model makes sense, as does the idea of spalling at the craton/lithosphere interface. Keep in mind that this part of the continental plate was fused to the core of the continent during the collision of plates estimated to have occurred some 200 million years ago. While maps and diagrams on a large scale present such boundaries as smooth and pretty, in nature, things tend to have more ragged edges until erosion smooths them out.
back to fracking:
Current fracs in this area (WIlliston Basin, Bakken/Three Forks) are on a 1280 acre lease, multistage, and involve about 3.5 million gallons of frac fluid. That seems like a lot, only consider there are 325,829 gallons in an acre foot (one foot of water covering one acre), roughly 10.7 acre feet (3.5 million gallons) of fluid spread over 1280 acres is only one tenth of an inch. Even allowing that the frac won't distribute over the full 1280 acres and the area will likely be more on the order of 320 acres of actual areal distribution, the whole amount of fluid injected amounts to less than a half inch were it laying on the surface. (four tenths of an inch, to be more precise, and some of that fluid will be entering porosity already present in the rock so the vertical displacement will be even less than .4 inches if distributed over the entire acreage). Not the sort of displacement noticeable earthquakes come from. By contrast, the Boxing Day earthquake (9.1) in Indonesia involved ten meters (32.5 feet) of vertical displacement.
Injection wells, however, are for the disposal of water and other fluids, and although these fluids are being placed in a porous rock layer (a mapable layer of rock with distinct characteristics is commonly referred to by geologists as a "formation") they will stay there, ideally, and the pressure increase near the wellbore as fluids are injected equalizes in the disposal formation as the fluid moves into the rock. If the fluid is injected too rapidly for that pressure to equalize, there will be some slight vertical displacement. If that formation is intersected by a fault, that fluid can lubricate (for want of a better term) the existing fault and release stress along the fault. There has been an association with injection wells and smaller quakes in just a few places (OK/KS border) because that depends on the geology in the area where the injection well is sited. In a multitude of other locations seismic disturbances related to disposal (injection) wells have been absent or unmeasurably small (ND, MT, WY).
There does not have to be vertical displacement along a fault to have an earthquake, as strike/slip faults have primarily horizontal motion and lateral displacement. For instance, there was a magnitude 8.1 earthquake in the Macquarie Islands three days from the Boxing Day earthquake, but the Macquarie Ridge earthquake caused no noticeable tsunami because it was a strike/slip fault and there was no vertical displacement, and no movement of seawater to cause a tsunami.
You can read panic inducing articles like this one:
https://www.rt.com/usa/fracking-earthquake-virginia-dc-817-061/ which completely fails to take into account things like the discontinuity of folded and eroded sedimentary rock layers from the West Virginia border to the igneous and metamorphic rock underlying the Mineral, Va, area, and they will induce fear of far reaching effects of a frac job which simply do not and cannot exist.
Other earthquakes have been noted in Virginia,
http://earthquake.usgs.gov/earthquakes/states/virginia/history.php and I have seen evidence of past seismic activity in broken speleothems in caves in the Gathright valley area (now Lake Moomaw) in Alleghany County, Va. The breaks were old, as new stalactite growth had occurred on the stubs. Keep in mind, though, that the source of this damage is likely from earthquakes which had their epicenters in Giles County. (The largest recorded earthquake in Va occurred there in 1897
http://earthquake.usgs.gov/earthquakes/states/?region=VirginiaMore information on the Geology of the piedmont region in Virginia and the 2011 earthquake here:
https://dmme.virginia.gov/DGMR/earthquake2011.shtml
