I'm going to visit Mount Gambier in a couple of weeks, which reminds me of an article I wrote years ago about the possibility of a volcanic eruption there.

Mount Gambier is in a volcanic region and the famous Blue Lake (pictured) is in a volcanic crater. There aren’t giant peaks, like Mt St Helens and elsewhere, just unimposing spikes to the obvious craters of Gambier and Shank.

We tend to think of the volcanoes as being extinct, while scientists tell us they are simply dormant and could erupt again at any time. The last eruption was about 4500 years ago.

Geologist Bernie Joyce attracted headlines in 2009 when he said authorities should consider the prospect of an eruption when planning for emergencies.

Joyce warned the consequences of even a small eruption coming into contact with groundwater could include hot, wet ash falls, dangerous gases and ash blown into the air, damage to animals and the environment, and pollution in water systems.

"It's far western Victoria, starting somewhere about Colac, through Camperdown, Warrnambool, across to the border and then in south-eastern South Australia, the area around Mount Gambier and Mount Shank, both of which are quite young volcanoes," he said.

"Then in Queensland there is a range of areas starting inland from Townsville where there has been some recent activity and it stretches all the way up to Cooktown.

"One area of particular interest is the Atherton Tableland where there are crater lakes very like Mount Gambier."

Eruption overdue

Associate Professor Joyce says for the past 40,000 years, new volcanoes in such areas have erupted about every 2,000 years, which means the next one could be near.

"Given that Mount Gambier, our youngest known one, erupted 5,000 years ago, we could be considered as overdue," he said.

He says while many eruptions are small and short-lived, some have the potential to blanket the country for up to 10 kilometres in ash, like the steam-driven explosion of South Australia's Mount Gambier.

He says other eruptions, like Victoria's Mount Elephant thousands of years ago, produced slow lava flows similar to the ones in Hawaii that are tourist attractions.

"The Mount Elephant type often produce lava flows and these can spread out for long distances running down valleys, destroying roads and railway bridges, destroying power lines and damming the water systems," he said.

Response plan

Associate Professor Joyce says lava flows would also increase the risk of grass and forest fires in western Victoria.

He says emergency management organisations should start looking towards response plans for volcanic eruptions.

"They are almost overnight things so when it happens you would need to have some information ready," he said.

"You would need to have some scenarios in mind. You would need to know who to contact and perhaps even to contact people from overseas who have been working on these sort of things. You need to get the experts in."

"People have, in other countries, tried to divert lava flows by cooling them with water, by building walls to make them go in another direction, by breaking the sides of the lava flows with explosives to try and get them to come out, therefore not continue down the valley where they are heading.

"These are the techniques we would to get from overseas and not ones that we have readily available in Australia."

Associate Professor Joyce says Australia could take its lead from New Zealand, which has similar volcano types, and which devotes a website, publicity and education to community risk information.

Reassuringly, his colleague Wally Johnson suggested there would be plenty of warning, most likely through rising water temperatures.

“We know that volcanoes do provide a fair bit of warning. In most cases this would be months or even years. You might get a volcano way out in Western Victoria where you might not notice the warning signs, but in most cases you’ll get advance warning from geological phenomena,” he said.

I came across a report by John O’Sullivan that quotes geology researcher Timothy Casey.

Casey disputes claims that man-made emissions of carbon dioxide have been causing ocean acidification.

After shaking off my instant aversion to any argument about the science of climate change, I read further that Casey’s study looked at examples such as the Blue Lake, which he says is acidifying due to volcanogenic CO2 input.

Casey claims this shows that Mount Gambier is not quite as dormant as we may have been led to believe.

“In fact, the lack of aquarium acidification is well known in the industry that supplies the pumps which aerate the water,” he writes.

“Unexpectedly, there is no demand for for any filtering equipment to remove the carbon dioxide from air pumped into aquarium water. If it is really true that the oceans are acidifying at the present time, then given that isolated water reservoirs and aquariums are not acidifying, the source cannot be common to both.

“This would exclude atmospheric carbon dioxide as a potential source of oceanic acidification.”

O’Sullivan comments: “If this fact was repeated worldwide, then it would dispel concerns that human-emitted greenhouse gases were the cause of rising levels of sea acidity. The real culprit seems to have been nature all along.”

I’m not sure about the scientific significance of these claims, but as a resident of Mount Gambier at the time, I was concerned in the short term about the acidification of the water and in the longer term about the risk of a volcanic eruption.

It’s true that authorities never seriously address these issues.