Tectonic pressure building along Queen Charlotte Fault

Experts studying the second-biggest earthquake measured in Canadian history have zeroed in on Haida Gwaii as the likely source of a future large quake and tsunami.

An earthquake off B.C.’s coast in the same area in October 2012 relieved some of the region’s tectonic strain, but new research shows the shifting also increased pressure immediately south of the islands along the Queen Charlotte Fault.

“What this has done in essence is raise the possibility of future thrust earthquakes and tsunamis along this part of the B.C. margin,” said Thomas James, a researcher with the Geological Survey of Canada.

James is one of the lead authors of a compendium of studies analyzing various facets of the recent earthquake, most of which were published Monday in the Bulletin of the Seismological Society of America.

The Pacific and North American tectonic plates mostly slide along one another, but where those plates meet at certain points along the Queen Charlotte Fault, they also push against each other, James explained. The release of that pressure gave rise to the thrust earthquake of 2012.

This type of earthquake is “unusual and to a certain degree unexpected” for the region, added James.

“Any large earthquake can generate a tsunami, but thrust earthquakes are especially effective.”

The scientists’ findings were revealed shortly after the provincial government released a consultation report that found B.C. is falling behind on earthquake preparedness.

The absence of major seismic activity near densely populated areas has contributed to a culture of public apathy and resulted in government diverting resources away from emergency management agencies, concluded the report prepared by American consultant Henry Renteria.

“The problem when you are living in earthquake country is that an earthquake is inevitable,” said Renteria in an interview.

“It is going to happen — it’s not a matter of if, it’s a matter of when.”

Renteria spoke critically of significant cutbacks and staffing shortages suffered by the province’s lead agencies responsible for earthquake and disaster management over the past 20 years, adding that the impact “is beginning to show.”

The report also highlighted the role of members of the public in contingency planning.

“Any large earthquake can generate a tsunami, but thrust earthquakes are especially effective.” — Thomas James