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Earthquakes: Where could the next big one hit?

Earthquakes: Where could the next big one hit?

As the death toll from the magnitude-7.8 earthquake that hit Nepal this past weekend continues to climb, naturally many inevitably ask where’s the next big one is going to hit? After all, the Himalayan region is only one of many tremor hotspots scattered around the globe.

While scientists are still not able to predict timing of when large tremors will happen next, they do know that they will occur where tectonic plates are under strain. A 2012 study found that of the 15 most massive earthquakes of the 20th century, 87 percent of the them occurred along what are known as fracture and subduction zones, where one tectonic plate slides underneath another.

Some of the most high risk countries where this can occur include Chile, Japan, New Zealand and Turkey. The larger cities have taken steps in having building codes to mitigate effects of earthquakes. However since we contract models and risk assessments based on data that covers only a little over century, scientists figure there are probably many hotspots that have remained unnoticed. For example, the region where Japan’s 2011 deadly 9.0-magnitude earthquake emanated from was never considered a significant risk.

Adding to the worry of course is that for developing nations where there is high levels of poverty, like Iran, Pakistan, and Indonesia, destruction is likely to be on the catastrophic scale.

And so where might the next big one hit? American seismologist Brian Tucker, being interviewed by Time magazine this week, said that he placed his bets on Sumatra suffering a repeat performance to what occurred just over a decade ago. In 2004, a 9.3-magnitude earthquake struck 100 miles off the northwest tip of Sumatra, Indonesia generating a huge tsunami that killed some 230,000 people, causing widespread devastation throughout the Indian Ocean basin.

How about here in Canada? Fortunately there has not been any major modern day event that caused large scale destruction, however the National Research Council of Canada says that many of the nation’s cities are ill-prepared.

On an average there are three to four tremors occurring somewhere in Canada on any day, most of them however are so small that they go unnoticed by all.

And while half of all quakes are felt across the west coast of Canada, putting cities like Victoria and Vancouver most at risk, eastern Canada has its fair share of potential seismic dangers as well.

Turns out there are fault lines that are known to exist across eastern Canada, running along the Ottawa and St.Lawrence valleys. In the last couple of decades these have been associated with at least a couple of well publicized magnitude-5 tremors across southern Ontario and western Quebec that was felt as far west as Sudbury and south down to New York City.

Back in 2013 the Insurance Bureau of Canada commissioned a study to see just how prepared eastern Canadians were for a big tremor.

They worked out a model where a 7.1-magnitude earthquake would strike the St. Lawrence valley, with tremors powerful enough to be felt over much of southern Quebec and Ontario and Atlantic provinces. Their results indicated that there would be a up to $61 billion in economic loss.

Interestingly, one of the world’s most powerful earthquakes ever did happen in Canada, back on January 26, 1700 along the Cascadian subduction zone along the west coast. Resulting landslides wiped out many Native villages on Vancouver Island, and also generated a giant tsunami that swept across the Pacific Ocean and devastated Japan.

Looking at the geological records, it seems that this was not a one-off event, but something that appears to reoccur every few hundred years.

At least thirteen giant earthquakes have occurred in the region in the last 6000 years. And in just the last 170 years there have been four magnitude-7 plus tremors felt across southwest B,C. and Washington state.