Macquarie Island expeditioners feel ‘deep rumbling’ of three earthquakes

Expeditioners on Macquarie Island have made a steep trek to high-ground after feeling a “deep rumbling”. Details >>

Macquarie Island – view from Wireless Hill, one of the muster points for expeditioners. Picture: Barry Becker/Australian Antarctic Division

A series of earthquakes in the Southern Ocean has rumbled Macquarie Island, motivating expeditioners to make a steep trek to high-ground for a precautionary drill.

Three earthquakes, as big as 6.8 magnitude, hit an area of the Southern Ocean within eight days.

The epicentre was about 500km south of Macquarie Island – with the effects felt by expeditioners even at a great distance.

“You could definitely hear and feel in your feet a deep rumbling,” Station Leader Justine Thompson said.

The Australian Antarctic Program has monitoring equipment at Macquarie Island, while Geoscience Australia monitors seismic activity across the globe.

Three earthquakes in eight days in the Southern Ocean prompted an extra muster drill for our Macquarie Island expeditioners. Could you make it up the 40 metre hill to the muster point?

Find out more 👉 https://t.co/KrbcysuOCTpic.twitter.com/rKM6HFR3qH

— antarctica.gov.au (@AusAntarctic) April 1, 2024

The data collected forms part of the global seismograph network.

Because Macquarie Island is located on a tectonic plate fault line, the plates which move against each other cause active activity close to the island.

“Macquarie Island is actually made up of bed rock from the bottom of the ocean. There are two tectonic plates that have been pushed together and they have produced the island we see today,” Australian Antarctic Division glaciologist Dr Ben Galton-Fenzi said.

Australian Antarctic Division Macquarie Island Station Leader Justine Thompson. Picture: Paul Black/Australian Antarctic Division

“When we have seismic activity, especially offshore, we can expect that there is a risk of tsunamis occurring. Not every earthquake results in a tsunami, but most tsunamis are the result of an earthquake.

“Even just a small change in the tide at a location at Macquarie Island is important to note and understand.”

With the increased seismic activity, expeditioners decided it was the perfect time to practise a tsunamis evacuation drill.

Tsunami shelter on Wireless Hill, a muster point for expeditions on Macquarie Island. Picture: Nick Cartwright/Australian Antarctic Division

While they are trained in the event of an earthquake and tsunami before they leave Australia, the training onsite reinforced the emergency response training.

“Our most recent tsunami exercise included a refresher on the Standard Operating Procedures, followed by a drill where the tsunami alarm was activated and all expeditioners mustered to the designated area,” Ms Thompson said.

At the sound of the alarm, it was a step trek for expeditioners walking the path to the Ham Shack. The shack is one of two muster points on the island that accommodates up to 40 expeditioners with food, shelter and clothing for 10 days.