Updates with statement from Natural Resources Canada, new filings by Enbridge Northern Gateway and the Attorney General of Canada (in box below)
The Geological Survey of Canada has identified a tsunami hazard and a possible seismic fault in Douglas Channel near Kitimat. A scientific paper by the Geological Survey and the Department of Fisheries and Oceans says there were once two giant landslides on Douglas Channel that triggered major tsunamis and that the landslides were possibly caused by an earthquake on the fault line.
Kitimat is the proposed site of the Enbridge Northern Gateway project and at least three liquified natural gas projects.
If the projects go ahead, hundreds of supertankers with either bitumen or LNG will be sailing in the channel for years to come.
A filing by the Attorney General of Canada with the Northern Gateway Joint Review Panel is asking the JRP for leave to file late written evidence long after the original deadline of December 2011. The Attorney General’s motion was filed on August 17, but went unnoticed until the Kitimat environmental group Douglas Channel Watch brought the matter up with District of Kitimat Council tonight (Sept. 17).
Appended to the Attorney General’s motion is a copy of a scientific paper from the Geological Survey “Submarine slope failures and tsunami hazards in coast British Columbia: Douglas Channel and Kitimat Arm” by Kim W Conway, J.V. Barrie of the Geological Survey and Richard E. Thomson of the Department of Fisheries and Oceans.
The report says the scientists discovered “evidence of large submarine slope failures in southern Douglas Channel.”
It goes on to say: “The failures comprise blocks of bedrock and related materials that appear to have been detached directly from the near shore off Hawkesbury Island.” Hawkesbury Island and many of the other islands in Douglas Channel are built up with material left over from the ice age glaciers and thus are vulnerable to displacement and landslides.
The research identified two slides, one estimated at 32 million cubic metres and a second of 31 million cubic metres. The report goes on to say that the discovery of an “apparently active fault presents the possibility that they may have been triggered by ground motion or surface rupture of the fault during past earthquake events.”
The slope failure landslides are covered with thick layers of mud, and that, the scientists say, could mean that the failures could be ancient, possibly occurring 5.000 to 10,000 years ago. Further research is needed to confirm the date of the giant slides.
What is worrying about the discovery is that fact that there were two recent submarine slope failures on the Kitimat Arm of Douglas Channel. both creating tsunamis. The first slope failure occurred on October 17, 1974, triggering a 2.4 metre tsunami at low tide. Then on April 27, 1975 there was a second slope failure near low tide on the northeast slope of the Kitimat Arm that generated an 8.2 metre tsunami. The 1975 tsunami destroyed the Northland Navigation dock near Kitimat and damaged the Haisla First Nation docks at Kitamaat Village.
The paper says that “Additional geological research is required to better delineate the age of the submarine failures, their triggers, and their mechanisms of emplacement.”
Urgent new research is underway and the filing by the Attorney General says when the Department of Justice requested leave to file late evidence says it anticipates that the further research by DFO is expected to be completed by November 1. The Natural Resources Canada Earth Sciences Sector began a national assessment of submarine slope failures in Canada in late 2011 and completion of the Pacific portion of this assessment is targeted for December of 2012.
The Attorney General’s filing says that DFO is now modelling “potential wave heights and speeds that may have resulted from the two previously unrecognized submarine slope failures in the Douglas Channel.” The model will use high resolution scans of the Douglas Channel seafloor to create the models.
The survey of Douglas Channel in 2010 suggests the possible existence of a fault immediately to the south of the second ancient slide on Hawkesbury Island.
The GSC paper says that evidence for a continuous fault was observed by aligned stream beds and fractures on the south end of Hawkesbury Island, about four kilometers from the site of the second ancient slide. The possible fault then appears to terminate far to the south near Aristazabal Island on the Inside Passage. The Geological Survey says that eleven small earthquakes, all less than magnitude three, have appeared with 20 kilometres of the suspected fault over the past 25 years.
The paper says that the scientists conclude that the slides appear to have left very steep slopes at or near the shoreline that could be susceptible to future failure events.
A large potential slope failure has been identified near one of the ancient slides….
in the absence of additional evidence, the fault must be considered a potential trigger for the submarine failure events….the triggers for the failures have not been defined; however, their proximity to a potentially active fault represents one potential source. The failures probably generated tsunamis during emplacement and conditions exist for similar failures and associated tsunamis to occur along this segment of Douglas Channel in the future.
The scientists say that detailed tsunami modelling is underway to
provide an improved understanding of the generation, propagation, attenuation, and likely coastal inundation of tsunami waves that would have been created by slides… or that could be generated from similar future events. Only through the development and application of this type of tsunami modelling will it be possible to gauge the level of hazard posed by the identified submarine slope failures to shore installations and infrastructure, or to devise ways to effectively mitigate the impacts of future such events.
The filing by the Attorney General offers to bring the scientists to the Joint Review Panel to appear as witnesses sometime during the final hearings.
The filing notes that the current evidence tendered to the JRP by Enbridge, and other parties does demonstrate the potential for marine geohazards and associated tsunami events. Enbridge’s design of the proposed Northern Gateway marine terminal and its operational plans took into consideration the current state of knowledge of geohazards including earthquakes and tsunamis at the time of filing. Enbridge has said it would undertake further geological survey during the detailed design phase for the terminal.
At the time Natural Resources Canada noted that the information provided for the Environmental Review was sufficient at that time, now the Attorney General says:
the geographic scope for potential landslide induced tsunami hazards is now better understood to extend beyond the Kitimat Arm. NRCan and DFO seek by this motion to ensure that this Panel, and the Parties before the Panel, have the most up to date information on geohazards in the Douglas Channel.
Updates: DFO report in October will clarify the tsunamis in Douglas Channel.
Statement from Natural Resources Canada
Natural Resources Canada sent this statement to Northwest Coast Energy News on September 20, 2012.
In reference to the opening paragraph of your September 18th editorial entitled Geological Survey of Canada identifies tsunami hazard: Possible fault line on Douglas Channel, we would like to clarify the following. Although the ancient large submarine slope failures which our scientists have identified may have caused tsunamis, this is not a certainty. It is important to note that Fisheries and Oceans Canada is currently studying this information to model potential wave heights and speeds.
As our report states, only through the development and application of this type of tsunami modelling will it be possible to gauge the level of hazard posed by the identified submarine slope failures to shore installations and infrastructure, or to devise ways to effectively mitigate the impacts of future such events.
Northern Gateway response filed on August 31, 2012
Enbridge Northern Gateway filed this response to the Attorney General’s motion on August 31.
This motion of the Federal Government Participants requests permission to file late evidence consisting of a report entitled “Submarine Slope Failures and
Tsunami Hazard in Coastal British Columbia: Douglas Channel and Kitimat Arm” regarding tsunami hazard and additional modelling work based on that report.
Northern Gateway does not object to the filing of this late intervenor evidence.
It may be relevant and Northern Gateway accepts that theevidence could not be filed earlier. However, Northern Gateway would like the opportunity to conductits own additional modelling work which it would be prepared to provide to DFO for comment prior to the filing of any modelling work by DFO in this proceeding.
Attorney General response to Enbridge on September 10, 2012.
The Attorney General of Canada responded to Enbridge by saying:
Attorney General responds DFo is prepared to await filing its subseqent modelling work in these proceedings until such time as it has received, reviewed and commented upon additional modelling work as proposed by NGP Inc.
DFO nots howeverand wishes to alert the JRP that the NGP INc proposed may occasion a delay in the filing of the DFO moedling work which is now proposed for filing on or about October 31, 2012. Delivery of DFO comments as requested will depend on when DFO received the NGP Inc modelling work, the time and resources required by DFO to study and provide comments on the NGP modelling work and unforeseen factors which may have an impact upon completion the commentary. As such,
DFO is prepared to file its modeling work on or about October 31, 2012, but subject to any further direction or request by the panel.
Department_of_Justice Notice of Motion of the Attorney General of Canada Seeking to Tender Supplementary Written Evidence (pdf)
Submarine Slope Failures and Tsunami Hazard in Coastal British Columbia Douglas Channel and Kitimat Arm PDF