3,742 earthquakes detected off Vancouver Island last week
The Province
06-Mar-2005
 Western Canada, last 5 years |
 BC, last 12 months |
VICTORIA -- Thousands of earthquakes have rattled the ocean floor off southern Vancouver Island last week, and a team of U.S. scientists is racing to the area to see if an underwater volcano is spewing fresh lava.
U.S. hydrophones detected 3,742 earthquakes over five days in an area about 270 kilometres west of Vancouver Island, but on Thursday, the intense activity calmed to just a few earthquakes an hour.
Scientists from all over the U.S. have scrambled to join the University of Washington research vessel Thompson, which is scheduled to arrive in the Endeavour Hot Vents area this morning.
The shaking is also being monitored by the Geological Survey of Canada through seismographs at the Institute of Ocean Sciences in North Saanich.
About three km below the ocean surface -- in the Juan de Fuca Ridge undersea mountain chain -- two tectonic plates, the Juan de Fuca Plate and the Pacific Plate, are pulling apart, said Geological Survey of Canada seismologist Garry Rogers.
"Most of the time, absolutely nothing happens out there, but every few years you get a burst of earthquakes," he said.
"It may signal the faults are moving or lava [is] being ejected on to the sea floor."
The U.S. scientific team will be investigating whether there has been an undersea volcanic eruption -- something that has never been witnessed, Rogers said.
If eruptions have finished, the scientists, armed with underwater cameras, will be looking for fresh lava filling up the kilometres-wide rift valley between the two plates.
"The new lava forms lumps right away. It's like putting hot fudge into cold water. It's known as pillow lava because it looks like little pillows," Rogers said. "They might see a big new area or nothing."
Scientists are trying to understand the plate-spreading process, which happens in oceans all around the world but has never been caught in action, Rogers said.
Scientists do not believe the intense activity poses any tsunami danger, Rogers said. "There's never been any tsunami generated by spreading, but we don't really understand the process."
The Endeavour Hot Vents is a federal marine protected area because of the unique biological community that lives around hot water geysers that result from the seismic activity.
About a dozen species of microbes are able to survive in boiling water and feed on hydrogen sulfide generated by the geysers.
The University of Victoria and University of Washington are collaborating on Project Neptune, an ambitious plan to have underwater observatories linked by thousands of kilometres of fibre optic cable feeding images to shore.