Earthquake aftershock event ‘longer than expected’
THE WHITSUNDAYS might be moving and shaking from a series of earthquakes, but experts say it is nothing to worry about.
A 2.9 magnitude earthquake was recorded about 50kms off the coast of Airlie Beach on February 14, sending lovers head over heels for Valentine’s Day – that is, if anyone felt it.
On the Geoscience Australia ‘felt tracker’ map, the tremor didn’t reach further than a few kilometres off the coast of Hook Island.
The earthquake was the second recorded this year, with over 80 tremors felt since an August 18, 2016 5.8 magnitude earthquake.
Geoscience senior seismologist Phil Cummins said the aftershocks were due to the initial 2016 earthquake, however the adjustment event was running ‘longer than expected’.
“Since the August 2016 earthquake there were 60 earthquakes above magnitude 2 in 2016, ten in 2017, five in 2018, three in 2019 and then 2020 has had two, so they are falling quite rapidly,” he said.
“When the main shock happens, it stresses the field around it and the aftershocks are the response as it adjusts.
“They seem to be flattening out and coming to a tail, although this aftershock event seems to be continuing for while than we would normally expect – and we’re not sure why that is.”
Mr Cummins said the proximity of this year’s two earthquakes was not a sign a larger earthquake would occur, although ‘you can never say with certainty’.
“You can never 100 per cent say something won’t happen and a large earthquake wouldn’t occur,” he said.
“Although there’s nothing I can see to say this isn’t normal activity after a large earthquake event.”
He said although earthquakes in Australia were rare, they were not unheard of, saying similar sized earthquakes had occurred over the last century in northern and central Queensland.
“There was a 5.9 recorded about 100kms off the coast of Gladstone in 1918, and there was a 5.8 recorded in Charters Towers in 1917,” Mr Cummins said.
“So they are around the region, we just don’t see a lot of them like areas such as Indonesia would.”