Media Releases >
Media Releases Archive
> Scientist unearths new potential cause of earthquakes
Scientist unearths new potential cause of earthquakes
Document Tools
March 31, 2004
A new theory about the cause of a multitude of earthquakes off coastal British Columbia and Washington State could lead to better prediction of, and preparation for, these potentially devastating shakeups. Andrew Calvert, an associate professor of earth sciences at Simon Fraser University has published a new study in the scientific journal Nature. (See March 26, 2004 issue at www.nature.com).
Calvert has connected the occurrence of hundreds of earthquakes in the last 10 years to the grinding of overlapping rocks trapped between two of the tectonic (structural) plates that form the surface of the Earth. A number of these earthquakes, occurring along the coast of Vancouver Island and in Puget Sound, have had a magnitude of greater than six on the Richter Scale. This worries engineers, city planners and emergency officials. "Their proximity to densely populated cities, such as Vancouver, Victoria and Seattle means they can do a lot of damage," notes Calvert.
These earthquakes erupt deep below the earth’s surface, approximately every 20 years. Calvert’s findings could make it easier for scientists to estimate the "maximum possible magnitude of these earthquakes and their potential damage in a given area." They are known as in-slab earthquakes. They occur 20 to 40 kilometres deep in rock forming the Juan de Fuca plate, a huge portion of the earth’s surface that is being forced down under North America.
Calvert has figured out that a layer of rock trapped between the Juan de Fuca plate and the North American plate, where the two should be abutting, is responsible for the quakes. "This new theory allows us to use controlled seismic surveys to map the faults and assess what’s going on," says Calvert. His theory is based on many such surveys, funded by the Geological Survey of Canada, the U.S. Geological Survey and the Natural Sciences and Engineering Research Council.
—30—
Websites:
Andrew Calvert: www.sfu.ca/earthsciences/people/faculty/calvert.html
Calvert’s article in Nature: www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v428/n6979/full/nature02372_fs.html
Natural Sciences & Engineering research council: www.nserc.ca