Dave Sullivan
Northern News Services

Yellowknife (Sep 12/01) - If Yellowknife's 18,000 people jumped up and down at the same time, would the earth move?

George Jensen figures probably, but it would be a weak blip registering at the seismic station he runs for the federal government, just outside Yellowknife.

Mildred Hall students Qumakuluk Dipizzo, 11, Skylar Cummings, 11, Philip Liske, 10, and Garret Sage, 11. - Dave Sullivan/NNSL photo

"That would be an interesting experiment. We should pick it up if they all jumped at the same time. It's theoretically possible, but everyone would have to hit the ground at exactly the same time."

Whipping out a calculator, Jensen guesses an average weight of 100 pounds, and wonders aloud how far off the ground people would jump.

"I doubt our sister station in Australia would pick it up though," he concludes.

Jensen manages Yellowknife's geophysical observatory, part of a global network of cold-war era buildings with sensitive instruments to detect earth tremors. The stations were built in the 1960s, to reveal if countries were testing nuclear explosives in violation of treaties.

The Yellowknife station didn't pick up any vibes from a nation-wide jumping experiment last Friday in England.

That's when an estimated million students from over 5,000 schools all jumped up at the same time -- 11 a.m. London time, to see what would happen.

It was all part of Science Year, a massive government initiative to get young people more interested in science.

Many of Britain's 140 seismic sensors picked up tiny vibes, says Science Year spokesperson Scott Swinton.

Before the minute-long jumping exercise, comments on a Web site from some of the young participants predicted calamity: earthquakes causing China to flood; or at the very least, a backlog of kids limping to British hospitals with sprained ankles.

"It went fine," Swinton said of the experiment.

"It'll be a couple of weeks before the final results are available."

The event may end up in the Guiness Book of Records.

In Yellowknife, seismic sensors at the observatory can pick up vibrations from around the world which are equivalent to 1,000 tons of dynamite. The fact the British Isles rest on a different tectonic plate system from Canada's Precambrian shield is one reason it's hard to detect when Britons jump, Jensen said.