Iceland volcanic eruption a reminder of Australia's explosive past

Tourists have been flocking to the eruption at Fagradalsfjall mountain, 32km south-west of capital Reykjavik, ever since it re-erupted after eight months of inactivity on August 3, 2022.

Monash Univserity volcanologist Heather Handley explained the eruption is relatively safe for tourists to visit.

"No volcano is predictable. But with the current lava flows that are coming out, it's a safer viewing than it would be for, say, something like in Indonesia where you're more prone to explosive behaviour," Professor Handley said.

The Fagradalsfjall eruption is a fissure eruption, which is a long, thin volcanic vent through which lava erupts.

"Normally, this type of eruption in Iceland is a very runny lava, so it kind of flows out. It's not like these big explosive eruptions," Professor Handley said.

"But if the magma mixes with something like groundwater, imagine there's an aquifer or there's some surface water like a lake, and then magma mixes with that. Then sometimes you can get explosive eruptions."

Another volcano in Iceland called Eyjafjallajkull erupted under 200m of glacial ice in 2010, which caused meltwater to flow back into the erupting volcano and increase the eruption's explosive power.

The volcano's enormous ash plume disrupted air travel in western Europe, resulting in what at the time was the largest air-traffic shut-down since World War II.

Australia's most recent volcanic eruption took place at Mount Gambier in South Australia around 5000 years ago.

In Mount Gambier's case, magma interacted with ground water to create an eruption with a volcanic explosivity index of four, which is a similar size to Iceland's Eyjafjallajkull eruption in 2010.

Given the similarity, in 2017, Monash University researchers used the ash cloud from the Eyjafjallajokull volcano to estimate the impact of a similar sized eruption in Australia and the southwest Pacific.

The resulting map showed an ash cloud hanging over Sydney, Melbourne, Canberra, Brisbane and Adelaide and reaching as far as Auckland and Wellington in New Zealand.

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Other Pacific neighbours such as Fiji, Vanuatu, New Caledonia and the Solomon Islands were also impacted.

Professor Handley said we could still see another eruption in the future within the active volcanic region within which Mount Gambier is located, called the Newer Volcanics Province - but the exact timeframe is unknown.

"It could be in a short amount of time. It could be in thousands of years from now. We just don't know when. But we consider that Newer Volcanics Province for which Mount Gambier sits is still an active volcanic area," she said.

Geoscience Australia, the government's technical advisor, classifies the area as dormant rather than extinct.