What’s with all the Fracking Earthquakes

Lynsey Kitching
 

 
Since 2003, there have been about 953 earthquakes in Northeastern BC. In 2008 alone there were 590. Honn Kao, Ph.D. Research Scientist, Seismology for the Pacific Geoscience Centre explains 2008 was tied to the investigation of fracking and seismic activity near Fort Nelson. From 2003 and the proceeding 17 years there were only about 185 events recorded by Natural Resource Canada (NRC).
 
Why the increase in earthquakes? Is it a natural occurrence? Could there be a link between an increased frequency of earthquakes and the new source for the natural gas extraction method of hydraulic fracturing aka fracking?
 
Fracking has been a method of extracting natural gas from the earth since 1958, however in the last five years, the method has taken an unconventional turn by trying to extract the gas from shale rock or sandstone. Hardy Friedrich, communications liaison for the Oil and Gas Commission of BC (OGC) says, “The source is unconventional, the shale and sandstone in the Montney Basin. In the Montney and Horn River basins, the gas is trapped in tight shale formations, not conventional reservoirs where there is kind of a pool of resources in the ground.” 
 
“Northeastern BC is considered part of the Canadian Cordillera. It is a tectonically active region. To the western side of this region is a zone which has frequent earthquakes and the highest seismic risk of the whole country.”
 
Part of the explanation for the earthquake increase in Northeastern BC over the last ten years is tied to accumulated tectonic stress in our region. Kao says, “We do know the occurrence of earthquakes requires an accumulation of tectonic stress. In places farther away from plate boundaries it takes longer for the geological system to accumulate the needed stress and information to generate earthquakes.”
 
The building up of tectonic stress is called a seismic cycle. We do not know how long a cycle actually is. Kao says, “It is a scientific question and it is very hard to answer. If we could answer that question, then we would have a very nice way to predict earthquakes. We know approximately based on plate motion about how long it will take, but it all depends on other factors that are beyond our observation or capabilities at the time being. That gives us a really big uncertainty in predicting cycles.”
 
Kao says when talking about smaller events, like a magnitude two or three earthquake, seismic cycles can occur more frequently because the required stress level is much lower. Most of the 953 earthquakes mentioned above were between a magnitude of two to four. Kao says, “The research is not yet complete. Once we get to smaller and smaller earthquakes it becomes more and more difficult for us to determine whether or not the geological system has already reached the critical stress. That is still a very big research topic.”
 
Kao then starts to explain the connection between fault lines and earthquakes. There are three different types of fault lines, active, inactive and blind faults. Most of Northeastern BC does not seem to have visible fault lines. This information comes from an online tool called iMap on the OGC website. Kao explains, “For the region where we do not have these fault lines there are two reasons. One is the region was basically stable over a long period of time; therefore there are no faults in that place either a long time ago or now. The other possible reason is what we call buried faults. You do have faults, but they are buried down beneath the surface and we have no way to know if the fault actually exists.”
 
Kao explains buried faults could be anywhere from a few km down in the ground up to a few tens of kms. During fracking, the wells are dug two to four and a half kms deep and could therefore be right near a blind fault and no one would be able to know. Kao explains why the understanding of blind faults is important to Northeastern BC.
 
“The key issue for those regions where you have blind faults and the region is still tectonically active, is you may not be able to know about the fault until it actually generates earthquakes. That has been documented all around the world; where previous studies indicate we don’t have a fault, yet earthquakes occurred.”

Between 2009 and 2011 there was a controversy around the earthquakes occurring in the Horn River Basin. The OGC released a report on the matter this year. A close town to the issues was Fort Nelson. The report from the OGC says, “The investigation has concluded the events observed within remote and isolated areas of the Horn River Basin between 2009 and 2011 were caused by fluid injection during hydraulic fracturing in proximity to pre-existing faults.”
 
The report goes on to state, “The Commission makes seven recommendations based on the investigation, which include the submission of microseismic reports; establishment of a notification and consultation procedure; studying the relationship of hydraulic fracturing parameters on seismicity, and upgrading and improving BC’s seismograph grid and monitoring procedures. In addition, the Commission has initiated a broader study with the University of British Columbia. The intent of this research is to provide insights into predicting the location and magnitude of seismic events based on hydraulic fracturing parameters, geomechanics and to establish protocols for prediction, detection, monitoring and mitigation of these events.”
As Kao stated above, being able to predict earthquakes is still out there in a gypsy’s magical glass ball, though technology has come a long way. Especially, because the earthquakes in the Horn River Basin much like here in the Montney Basin region are smaller on the Richter scale. The report from the OGC states, “A search of the areas in the National Earthquake Database from 1985 to present shows no detected seismicity in the Horn River Basin prior to 2009.”
 
Kao says, “The number of seismic events does appear to increase with the operation of fracking activity in the Horn River Basin.”
 
The OGC and NRC have established a formal collaboration to enhance seismic monitoring capabilities for the region. Kao says, “We want to learn more about the nature of the induced seismicity and how it’s related to fracking operations and their control parameters. We are actively working on this research. We really need clear evidence in order to draw conclusion as the topic is becoming more and more sensitive.”
 
Freidrich says in regards to the report and the collaboration with NRC, “One of the recommendations was to increase the amount of seismic monitoring in Northeastern BC as a whole. Looking at all of Northeastern BC is the direction all the initiatives are going. Majority of the fracking activity in the province is in Northeastern BC. From our perspective having the increased monitoring will give BC a better idea of what’s happening underneath the ground.”
 
During the presentation from the OGC here in Tumbler Ridge, the main focus of the discussion was based around our aquifer and the group presented a very convincing argument as to why fracking cannot harm our aquifer. However, Mayor Darwin Wren still has concerns fracking has the potential to harm our main water source. What happens if there is an earthquake, be it fracking induced or natural?
 
There are different ways the Tumbler Ridge aquifer could get harmed through the practice of nearby fracking and there is also a chance it could not get harmed at all. Or on the extreme side, similar to what happened to the hot springs near Haida Gwaii, the water could just disappear. Kao says, “The aquifer is a very complex system. Around the world there has been quite a bit of documentation indicating when earthquakes occur, the water system sometimes reacts. That is something that has been documented very widely around the world. The latest example is what occurred in the Haida Gwaii area. Right after the earthquake, the residences noticed their hot spring dried up,” Kao continues, “That means the occurrence of earthquakes sometimes does have an impact on hydrological systems. It happens, people document it, but no one can say it will happen every time earthquakes occur. There are other factors that may affect the interaction between earthquake systems and hydrological systems. It becomes a very difficult issue to answer.”
 
The chance of our aquifer suddenly drying up due to fracking induced earthquakes is probably unlikely, but not out of the question. Mayor Wren points to his biggest concern. “I was talking to a few people down in Victoria at the UBCM about fracking. Would we be able to enforce no fracking within say five km of the aquifer?”
 
Wren continues, “In some ways no, probably not, but if we move forward with the resolution anyway it’s going to raise the profile of the issue. There are other areas where they have misjudged and have destroyed some aquifers,” he continues, talking about the connection between fracking and earthquakes, “With fracking you’re pumping all this liquid down there. The notion is the bedrock is going to protect the aquifer. An earthquake cracks the barrier of the bedrock. If it cracks, that stuff is going into the water, there’s no doubt about it. The earthquake itself would open channels for the liquid to flow. In theory they are saying the bedrock is the protection. With an earthquake, that theory isn’t going to hold.”
 
There still needs to be much research done into the connection between fracking and earthquakes. With the research being done and the events near Fort Nelson, there seems to be some correlation between the two. Since the technology does not exist to predict earthquakes or to be able to detect blind faults, the practice of fracking too close to the Tumbler Ridge aquifer could, for some, seem risky. The bottom line is we just don’t know yet, but is the safety of our water source something we’re willing to roll the dice on?