zombola
01-06-2015, 01:17 PM
VANCOUVER -- While it's unusual for seven moderate quakes to rock B.C.'s coast in such a short period, they could also be foreshocks leading to a larger earthquake.
Over the holiday break, the West Coast region off of Vancouver Island became even more of an earthquake hotspot.
On Jan. 3, a 4.5-magnitude hit 208 kilometres west of Port Hardy, B.C., and on Friday a 5.4-magnitude struck 211 kilometres out in the same region, which was lightly felt in Campbell River, Vancouver and New Westminster. There were no reports of damage.
Then there were five more reported by Earthquakes Canada between Dec. 20 and 21 in the four- and six-magnitude range about 200 km offshore of Port Hardy.
According to John Clague, a Simon Fraser University professor, a larger earthquake off Vancouver Island's shore could be around the corner.
"It is an earthquake-prone territory, but this is a fairly large number of earthquakes to have in such a short period," he said. "It's possible we won't know until time passes that these could be foreshocks of a larger earthquake in the same area, something in the magnitude six or seven range."
It's normal for a cluster of earthquakes to hit along the border of the Juan de Fuca and North American plates, he said, and it's unlikely any damage will result from a seven-magnitude quake as long as it remains offshore.
"All these plates border one another along major active faults," he said. "It's far enough offshore you wouldn't expect any damage sourced in that area."
Although the slew of tremblors have been frequent, there's no direct link for it to trigger the "big one" further south on the Juan de Fuca plate and the Cascadia Subduction Zone, he said.
"We don't know," Clague said, regarding any foreshocks precipitating the predicted nine-magnitude earthquake that may someday hit B.C.'s southern coast.
"We could look at comparing against the nine-magnitude earthquakes in other parts of the world like in Japan in 2011 or Sumatra in 2004, there were no foreshocks at all."
cbc.ca
Over the holiday break, the West Coast region off of Vancouver Island became even more of an earthquake hotspot.
On Jan. 3, a 4.5-magnitude hit 208 kilometres west of Port Hardy, B.C., and on Friday a 5.4-magnitude struck 211 kilometres out in the same region, which was lightly felt in Campbell River, Vancouver and New Westminster. There were no reports of damage.
Then there were five more reported by Earthquakes Canada between Dec. 20 and 21 in the four- and six-magnitude range about 200 km offshore of Port Hardy.
According to John Clague, a Simon Fraser University professor, a larger earthquake off Vancouver Island's shore could be around the corner.
"It is an earthquake-prone territory, but this is a fairly large number of earthquakes to have in such a short period," he said. "It's possible we won't know until time passes that these could be foreshocks of a larger earthquake in the same area, something in the magnitude six or seven range."
It's normal for a cluster of earthquakes to hit along the border of the Juan de Fuca and North American plates, he said, and it's unlikely any damage will result from a seven-magnitude quake as long as it remains offshore.
"All these plates border one another along major active faults," he said. "It's far enough offshore you wouldn't expect any damage sourced in that area."
Although the slew of tremblors have been frequent, there's no direct link for it to trigger the "big one" further south on the Juan de Fuca plate and the Cascadia Subduction Zone, he said.
"We don't know," Clague said, regarding any foreshocks precipitating the predicted nine-magnitude earthquake that may someday hit B.C.'s southern coast.
"We could look at comparing against the nine-magnitude earthquakes in other parts of the world like in Japan in 2011 or Sumatra in 2004, there were no foreshocks at all."
cbc.ca