Queensland earthquake: Aftershocks will be felt for ‘weeks’

The location of an earthquake that struck off Bowen early on Friday morning. Photo: Geioscience AustraliaThe aftershocks from Thursday’s earthquake off the Queensland coast will be felt for “weeks”, a seismologist says, after a smaller earthquake hit near Airlie Beach on Friday.
Nanjing Night Net

Thursday’s magnitude 5.8 earthquake was recorded about 70 kilometres off the coast, north-east of Bowen, caused six aftershocks, including a magnitude 4, in the following hours.

Three schools and Cairns airport were shut down temporarily, while several buildings in Townsville’s CBD were evacuated.

On Friday, residents and tourists at Airlie Beach woke to a magnitude three earthquake that occurred nearby at 7.37am.

Geoscience Australia senior seismologist Jonathan Bathgate said the aftershocks would continue for weeks.

“We would expect the aftershock sequence from yesterday to continue for a while, a few weeks at least, but apart from that we really can’t predict if there is going to be another sequence somewhere along the coast,” he said.

Mr Bathgate said the aftershocks were the result of fault lines readjusting back to equilibrium.

“You get the main shock that is a really big movement of the faults and the period after that is the fault readjusting itself back to equilibrium state,” he said.

“If you move something really quickly and then let it go it takes a bit of time to reach an equilibrium state so these are all just small adjustments to get it into a point where the fault will start again to build up some stress on that fault and lock together until it goes again some time in future.”

Earthquakes occur in Queensland due to the Australian plate moving northward, about seven centimetres a year, and colliding with the Pacific plate.

This causes stress to build up, which is released by earthquakes that Mr Bathgate said could not be predicted.

“It is something we don’t know, we can’t predict where it is going to occur or when so at the moment it is just a matter of monitoring the area,” he said.

“We are sending out some extra monitoring equipment over the next week to deploy on some of the islands and along the coast line to get a better idea of where the activity is occurring and get a better idea of what is causing it.”

Mr Bathgate said the region near Bowen had been quite active over the last 18 months.

“In terms of what we have recorded, it has been active over the last 18 months, the area does have a history of activity, but it has not been as frequent as it has,” he said.

“We know the area gets earthquakes but they are generally not that common.”

The Bowen area was also hit in 2011 with a magnitude 5.3 earthquake that was significantly closer to the coast than yesterday’s incident.

Queensland’s largest recorded earthquake was a magnitude 6 in 1918 that originated near Lady Elliott Island and was felt from Mackay to Grafton.

The state’s second largest was Thursday’s earthquake, followed closely by a 5.4 magnitude earthquake in 2015 that was recorded east of Fraser Island.

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