Yellowknife (Oct 13/06) - North Korea's alleged underground test of a nuclear weapon early Monday morning was detected by seismic monitors in the Yellowknife region.

"We did record a little bit of the signal at the Yellowknife station," said Alison Bird, earthquake seismologist with the Geological Survey of Canada in British Columbia.

The results surprised Bird because according to her, seismic events on the other side of the planet with a magnitude of four or less rarely register. North Korea's test measured 3.9.

"I think the last major event recorded (in Yellowknife) was an earthquake in the north of Japan," said Bird. "And that was a six magnitude."

The monitoring stations in this region are part of a network implemented by the United Nations following the ratification of the Partial Test Ban Treaty in the '60s.

After signatories pledged to halt underground testing of nuclear weapons, the UN required a system to ensure countries were abiding by the agreement and turned to Natural Resources Canada for help.

"In 1959 a group of scientists got together in Geneva and were looking at using seismic technology to detect earthquakes," said George Jensen, officer in charge of the Yellowknife Geophysical Observatory. "After the underground test ban treaty this facility began collecting seismic data in 1962 and went digital in 1986."

Jensen says the monitoring station collects data from two seismic arrays - one which measures sharp bumps and a broadband array designed "to measure really long period ground velocities."

While data on earthquakes around the world registers is analyzed and shared for scientific purposes, the primary function of the Yellowknife array is to listen for underground nuclear tests.

Canada ratified the Comprehensive Test Ban Treaty in 1998, which prohibits any nuclear weapons testing of any kind. Since that time Jensen said the combination of

seismic arrays, infrasound,

hydro-acoustic, radio nuclied (measures for radioactive particles in atmosphere) and space technology in Canada "has got the planet covered."

North Korea was not one of more than 170 nations who have since signed the test ban pact, and they pulled out of the Nuclear Nonproliferation Treaty in 2003.

However, whether the test was successful or even involved a nuclear device is unclear. Russia has been the only country, thus far, to confirm North Korea's claim it successfully detonated a nuclear weapon.