Jessica Klinkenberg
Northern News Services
Published Friday, September 7, 2007

YELLOWKNIFE - The loud boom and brief rumbling across Yellowknife on Monday was caused by blasting at a nearby rock quarry.

Blasting at the RTL quarry on Monday caused the shaking that occurred in Yellowknife late Monday afternoon. This picture is of roadside blasting on the Ingraham Trail in 2004. - NNSL file photo

Roger Mann, owner of Break-Away Drilling and Blasting, said the blast at the RTL rock quarry near the city dump was no different than previous work done by his company.

"I just blasted a quarry, same as I did with the other quarries," Mann said.

He said he was blasting for gravel for the roads.

"The wind direction was (towards) the city. We don't like to blast when it goes in that direction.".

However, because there was no cloud cover and winds were low he determined the conditioning safe.

The NWT Workers Compensation Board looked into the incident and found that the company did nothing wrong, according to Dave Grundy, manager of communications and information with WCB.

However, unlike Mann, Grundy said there was cloud cover that day and those clouds could have played a part in the intensity of the blast.

"The cloud cover stops the shock wave from escaping, that's why the shock wave will carry so far," Grundy explained.

Although he said the blasting company followed all the proper procedures under the Mine Health and Safety Act, the WCB will still send a mine inspector to the site in an effort to determine what could have magnified the effect.

John Cassidy, a seismologist with Earthquakes Canada, said he did see some activity in Yellowknife on Sept. 3.

"There does seem to be a little spike a couple seconds before 4:30," said Cassidy.

Rick Miller, operations manager with NWT Rock Services said that they've been receiving calls inquiring about the rumbling, though he said they weren't blasting at that time.

He said he was in his home on the other side of town when it happened.

"To hear it that far away is exceptional," he said.

In October 2004 a similar blast was heard from 30 kilometres outside of Yellowknife as work was being done on the yet-incomplete Highway 3.

According to Yellowknifer's reports from that time, the explosion registered 3.0 on the Richter Scale in the NWT capital.

Grundy said he's lived in Yellowknife for decades and he remembers the blast in 2004 and others before that.

"I've lived here for 30 years, and when Giant and Con mine were going flat-out the city shook a lot," he said.