Earthquake mystery solved as nearby quarry puts its hand up

A regular-intensity and scheduled explosive blast at the Boral quarry in Dunnstown was responsible for yesterday’s earthquake alert, says both the company who fired the shot and Geoscience Australia.

Luis Garcia of Boral’s media representative Cannings Communications told The Courier that the Boral quarry conducted a regular monthly ‘shot’ (blast) to expose the basalt rock processed at the site. A shot took place yesterday at 12.04pm, which would most likely account for the reading.

Senior seismologist with Geoscience Australia Jonathon Bathgate concurred, saying the geological organisation confirmed the blast was responsible for the elevated reading.

The reading was taken at the Ballarat seismic monitoring station and several others in Victoria.

In an interview with The Courier, Mr Bathgate said Geoscience Australia had a series of around 100 seismic monitoring stations spread around quieter regions of Australia, and a smaller urban network established following the 1989 Newcastle earthquake.

Ballarat’s seismic station is part of the urban network.

A small disturbance such as yesterday’s is a line call for the organisation, said Mr Bathgate.

“It’s a difficult game to play,” he said. 

“This was a relatively small reading, so it was hard to locate. It can be hard to differentiate, so these readings are sent for an initial review. They are not necessarily right on top of a mine.”

Mr Bathgate said while the earthquake feed for Geoscience Australia adds data automatically, it is always reviewed by a seismologist.

“So that’s why the earthquake originally reported yesterday was removed,” Mr Bathgate said.

UPDATE: WEDNESDAY 9.30am

A spokesperson for Castlemaine Goldfields Pty Ltd, the company responsible for the Mt Clear gold mine management in Ballarat, says they were not blasting yesterday.

The spokesperson said the company had also been contacted by Geoscience Australia, and had confirmed blasting was due to recommence today.

“So you might get another reading sometime this afternoon, but definitely not yesterday,” the spokesperson said.

Both Walsh Quarries and Boral Quarries at Dunnstown conduct blasting in the course of their works.

Walsh Quarries also confirmed they were not working yesterday. Boral Quarries said they would investigate whether a shot took place yesterday at their site and inform The Courier.

MORE TO COME

UPDATE: 2.10pm 

A media spokesperson for Geoscience Australia has confirmed the movement felt this afternoon near Bungaree was not a earthquake, but a mine blast instead.

A seismologist went back through the data gathered at 12.06pm and revised the original finding of a magnitude 1.8 earthquake, saying it could have been a mine blast that created the reading, taking Ballarat’s mining industry into consideration. 

UPDATE: 1.30pm

An earthquake has been recorded just outside Ballarat this afternoon.

The quake hit Bungaree at 12.06pm, according to Geoscience Australia Earthquakes, registering at a magnitude of 1.8.

Notification of the earthquake was issued via the emergency alert app.

The Courier contacted the post office at Bungaree, which is 600 metres away from the epicenter of the earthquake. The post office’s manager Cynthia said no one in the business felt anything at 12.06pm.

It remains unclear if there is any damage at this point.

According to the Geoscience Australia Earthquakes website, “estimated damage and felt radius cannot be calculated for this earthquake because the magnitude is less than 3.0”.

THIS WAS POSTED BY THE SES YESTERDAY

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