Intense earthquake activity on the ocean floor off the coast of southern Vancouver Island has scientists scrambling to be the first to catch a glimpse of two tectonic plates pulling apart.
U.S. scientists from the University of Washington sent a research vessel over the weekend after seismic equipment detected nearly 3,800 small quakes in an area known as the Endeavour Hot Vents on Thursday.
“The speculation is it might be a volcanic eruption or a magma event on the ridge,” said Garry Rogers, a seismologist with the Geological Survey of Canada.
“Thousands of earthquakes occurring over a few days, it’s a tremendous amount of energy but it’s way offshore,” he said on Sunday.
“They are too far to be felt so as far as we know there is no threat.”
The latest in this series of ocean floor earthquakes was a 4.1 magnitude quake at 5:01 a.m. Sunday about 100 kilometres north of the swarm activity the Northern Juan de Fuca Ridge.
“Just to remind us it’s a very active earthquake area,” he said.
The Endeavour Hot Vents are a 10-kilometre segment of the ridge located in 2,250 metres of water about 250 kilometres off the southern coast of Vancouver Island.
In June 2001 the federal government designated it a Canadian Marine Protected Area.
The ridge is usually quiet where the plates are moving apart but suddenly there are intense bursts, said Rogers.
“We saw them in 1999 and 2001 going on for a week or so with a thousand quakes but there’s never been a ship out there when this is happening to see exactly if there is magma being ejected on the sea floor.”
Experts agree the Juan de Fuca Plate and the Pacific Plate are pushing together and will one day lead to a large earthquake rocking the western coast of North America.
It’s unclear when the inevitable shaker will occur because scientists don’t know how fast the plates are moving.
“Is it millimetres over many years? Is it all of a sudden centimetres or even metres in the period of a few minutes or seconds during these earthquake swarms? We really don’t know that,” said Rogers.
That’s why the U.S. scientists sent the Thompson research ship this weekend, he said, to shed light on the plate-spreading process, noting he hoped to have more information on what they find this week.
Rogers agreed the current quake activity is intense but it’s not likely to cause a tsunami like the devastating one that hit southern Asia on Boxing Day.
“We don’t feel there is a tsunami threat even though there is vertical motion in that we have never seen a tsunami generated from a mid-ocean ridge.”
Rogers said a new program that will be launched in 2007 called Project Neptune will help scientists monitor potential tsunami threats.
The project will lay a 3,000-kilometre network of powered fibre optic cable on the seabed over the Juan de Fuca Plate.
The network will be made up of 30 or more sea floor labs so land-based scientists can collect data from the ocean surface to under the sea floor.
Instruments will be interactive so scientists can respond to earthquakes, tsunamis, and underwater volcanic eruptions as they happen instead of dispatching research boats.