© Nick Murray/News Staff
A map showing earthquakes and the various tectonic plates around the Pacific Ocean.
According to seismologists, Vancouver Island is overdue for a magnitude 7 earthquake and
has entered a period of time where an additional magnitude 9 mega-thrust rupture earthquake, likely to cause a tsunami, can be expected.
"In our part of the world, there are the big Pacific and North American [tectonic] plates, and caught in-between the two is the Juan de Fuca plate system," says Taimi Mulder, seismologist at the Geological Survey of Canada (GSC), which monitors all seismic activity in Western Canada.
Over millions of years, these plates push and grind under and past each other in areas called subduction zones. Earthquakes are caused and can be tiny or they can be massive, like the 2004 Sumatran earthquake, which ruptured 1,000 kilometres of coastline.
"An earthquake is like ringing a bell. The earthquake is the clapper that sets it off and the bell reverberates," said Mulder. "In an earthquake, energy is sent shooting in all directions and it pings around inside the earth making the whole earth vibrate."
Magnitude 4 or 5 earthquakes will likely wake you up, while a 7 will result in toppled bookcases and fallen chimneys. Thanks to B.C.'s stringent building code, structural collapse is not expected in magnitude 7s. Magnitude 8 or 9s have the same severity of shaking as a 7, but their duration lasts longer, often over 2 or 3 minutes. They cause structural building damage and ruptured gas lines, often causing fire.
