Australian expeditioners on sub-Antarctic Macquarie Island Research Station conducted a high-ground evacuation drill after a series of earthquakes shook the island in March. Three earthquakes hit an area of the Southern Ocean some 500 kilometres south of Macquarie Island, the biggest a magnitude 6.8.

While the station is always at the ready for seismic activity, three earthquakes in eight days provided motivation for an extra drill. 

Station Leader Justine Thompson says while the impact area was a long way from the island, it was still felt by many of the expeditioners.

“You could definitely hear and feel in your feet a deep rumbling,” she said.

Geoscience Australia monitors seismic activity across the globe and the Australian Antarctic Program has monitoring equipment at several Antarctic research stations, including Macquarie Island.

The data recorded from the stations forms part of the global seismograph network that monitors earthquakes world-wide.

As well as seismic activity monitoring, Australia's 70-year presence on the island also includes long-term scientific monitoring of wildlife, climate data and radiation monitoring, to detect evidence of nuclear explosions. 

Macquarie Island formed by “two tectonic plates sliding together”

Australian Antarctic Division Ice Sheet and Sea Level Section Coordinator, Dr Ben Galton-Fenzi says the area where Macquarie Island is located is a particularly active seismic area, due to its location on the tectonic plate fault lines.

“The two plates on either side of Macquarie Island are sliding against each other,” Dr Galton-Fenzi said.

These plates can move against each other and cause earthquake activity close to Macquarie Island.

“When we have seismic activity, especially offshore, we can expect that there is a risk of tsunamis occurring. 

Earthquakes can trigger tsunami’s through violent movement in the seafloor or by triggering huge undersea landslides," Dr Galton-Fenzi said. 

Expeditioners practice tsunami evacuation drills

Expeditioners are trained on what to do in an earthquake and tsunami before they leave Australia.

The training covers what the different alarms sound like and the procedures around mustering and getting to safety.

“This training is reinforced on station through emergency response training,” Ms Thompson said.

“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.”

When the alarm went off, expeditioners had to evacuate up a steep path to what is known as the Ham Shack. 

It's one of two muster points on the island. The other, Wireless Hill, sits at around 100 metres elevation. 

While the recent run of earthquakes didn't require expeditioners to go to higher ground, the muster site is well-equipped to support an emergency evacuation, with clothing, shelter and food to accommodate up to 40 expeditioners for 10 days.