Yellowknife (Oct 15/04) - A blast shook Yellowknife at 7:49 p.m. Tuesday, rattling houses on Latham Island and in the downtown core.

The explosion registered at 3.0 on the Richter scale, but it wasn't an earthquake.

Blasting like this May explosion had many people thinking Yellowknife was rocked with an earthquake Tuesday evening. NWT Rock Services used up to 15,000 kg of explosive to move 12,000 cubic metres of rock. - NNSL file photo

"Blasts look a little bit different than earthquakes because some of their energy is lost to the air," said Sylvia Hayek, a seismologist with Natural Resources Canada.

NWT Rock Services confirmed they were blasting on Highway 3, about 25 kilometres west of Yellowknife at approximately 7:50 p.m. on Oct. 12.

Trevor Heard, general manager of NWT Rock Services, said the blast moved about 12,000 cubic metres of rock using 10,000 to 15,000kg of ammonium nitrate.

He said that's not a large blast charge.

"It wasn't anything unusual that we were doing out there," he said.

NWT Rock Services is working on a government-sponsored re-alignment of Highway 3. Work on the latest phase began in May.

Heard said they were blasting in the evening because there had been some delays on the site that day.

NWT Rock Services has sent a letter to people who live along Highway 3, warning them that their houses could be damaged in the blasting.

That, together with the magnitude of Tuesday's blast, has residents worried.

"We thought a plane had crashed," said Timothy Caisse, who lives three km from the blast site. "If I lived a little closer to the highway, I'd have thought a tractor trailer ran into my house."

He said he's concerned about the effect on wildlife in the area, especially on moose.

"My cat ran crazy for about 10 minutes, wild-eyed," said Caisse. "We're not going to have anything to hunt this winter if they keep it up."

Contractor is liable

NWT Rock Services is liable for any damage to property along the highway. Heard said some residents may be asked to leave their homes for about a half-hour during blasting.

"There's no one who lives in the immediate area," said Heard. He wasn't sure why that blast was felt so far away.

"It could just be the rock conditions," he said.

"I don't think this one was any different from other blasts we've shot."

Seismologists are looking into the event. Hayek said they usually assume that small shakes are from the mines around Yellowknife. She said they pinpoint blasts in accordance with the international Nuclear Test Ban Treaty.

"We triangulate the exact location of blasts to confirm that they are not nuclear," said Hayek.