This op-ed was originally posted on the Chronicle Herald.
Photo credit: Chronicle Herald
On the subject of fracking, I commend the government of Nova Scotia when it states that all information possible must be considered.
Here are some facts to consider.
There is no question that someone might make money in extracting the trapped gasses in the rock formations underlying certain regions of our province. Nova Scotia is exceptional when it comes to its geological makeup and history. It was glaciated beginning approximately two million years ago and ending 9,000 years ago. When maximum thickness of glacial ice was on top of Nova Scotia (1.5 kilometres or one mile thick), the weight of the ice pushed the rock crust of the Earth down.
This displaced the hot, pliable mantle rocks beneath the crust to the side and outwards, where there was no weight from the overlying crustal rocks and glacial ice. This created a bulge in the displaced mantle material under the crust, which is referred to as the peripheral bulge. As stated in the scientific paper by Garry Quinlan and Christopher Beaumont of the Department of Oceanography, Dalhousie University, in 1981:
“As this ice melts the resulting isostatic disequilibrium causes this material to flow back from the bulge toward the rebounding ice centre. The large North American ice sheets did not melt instantaneously and the bulge produced by this ice migrated inward through Atlantic Canada following the retreating ice edge. This migration, involving mass redistribution in the highly viscous interior of the Earth, could not keep pace with the comparatively rapid glacial retreat and, therefore, continued to take place long after deglaciation was complete.”
When the glacial ice melted away, that peripheral bulge began to move back to the northwest. The bulge is presently beneath Hants, Cumberland and Colchester counties and parts of Cape Breton.
The bulge is causing our province to tilt. The Atlantic shore of Nova Scotia is descending at a rate of about 30 cm (one foot) per hundred years and the Fundy/Chignecto area is rising.
Physical evidence of the sinking land can be seen in Louisbourg. The mooring ring on the wharf now sits approximately 60 cm (two feet) below high tide. The Chignecto shoreline is rising, as evidenced by the raised beaches (beaches originally formed at sea level but are now higher than sea level) in several areas. This can be seen at Sand Cove in Cape Chignecto Provincial Park. It is the rising of the landforms (or isostatic readjustment) and associated upwards pressures that are of concern.
Springhill has tragically lost many miners to a phenomenon known as a “bump.” That is when the floor of the mine, weakened by the mining process, suddenly and catastrophically ruptures and crashes into the roof of the mine. A bump is felt above ground as a minor earthquake.
Injection of fracking fluids at depth may cause similar bumps by fracturing the rock and providing mechanisms for the rock to give way more easily. Although the quakes may be relatively minor and between 3 and 5 on the Richter scale, they will still be felt and may be quite unnerving.
Earthquakes have gone from no more than a dozen a year in Oklahoma to 888 per year today. This is widely attributed to fracking and the disposal of oil-drilling byproducts and other waste water injections into the rock formations.
The likelihood and potential risk of increased minor earthquakes in Nova Scotia must be taken into consideration.
In addition, it should be noted that the vertical shear strain rate is highest under Cumberland, Hants, Colchester counties and parts of Cape Breton — locations of the preferred sediments to be drilled for fracking. Some very serious research needs to be done, and unbiased information provided.
Fracking weakens the structural integrity of the rock into which the fracking fluids are injected. This weakening may create a situation similar to the underground mining in Springhill and its inherent weakening of the bedrock there.
If the people living in the areas deemed prime for fracking, as listed in the Onshore Petroleum Atlas recently released by the Nova Scotia Department of Energy, are content to have their homes shaken, animals agitated, and are OK with the possible risk to their groundwater, then fracking may be acceptable there.
If not, then perhaps the moratorium should be proclaimed and remain in effect indefinitely.
Robert G. Grantham is a retired geologist who lives in Stewiacke.