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Australia ‘overdue’ for volcanic eruption? 21 September 2009

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Middle and Valley Lake Craters of Mount Gambier - illustration from 1862

Is Australia ‘overdue’ for a potentially hazardous and destructive volcanic eruption?

Australia is not a continent normally associated with active volcanism: the Global Volcanism Program currently lists a grand total of ‘1 Holocene volcano’, although that ‘volcano’ is the extensive Newer Volcanic Province in south-east Australia. The province stretches across 15000 sq km of the states of Victoria and South Australia, and consists of around 400 small shield volcanoes and explosive vents active from the Tertiary to the Holocene, with the most recent eruptions at Mount Gambier (PDF) dated to around 4,000-5,000 years ago.

As the example of the Newer Volcanic Province indicates, there is plenty of evidence of volcanic activity in Australia: Geoscience Australia notes that ‘Evidence for volcanism throughout geological time can be found in every [Australian] State and Territory, with extensive volcanism down the east coast during the past 60 million years’. The east coast volcanism is put down to the Australian continent moving from south to north over a hot spot, so that the youngest volcanism is found in the south. There was some volcanic activity in Queensland as recently as around 10,000 years ago. Lava flows from Toomba vent on Nulla volcano have been dated to 13,000 years ago. This eruption, along with others in recent Australian geological history in both north and south, was almost certainly witnessed by the human inhabitants of the area (PDF) and recorded in their mythology. The south-eastern Australian volcanoes are generally regarded as ‘dormant’, the northern volcanoes as ‘extinct’; but all these extinct/dormant/active labels are rather arbitrary.

The point of all this is that Australia does have a history of fairly recent volcanism. Does that mean there is a significant volcanic eruption risk that Australians should be worrying about? Prof Bernie Joyce of the University of Melbourne thinks so:

Emergency services should prepare for volcano eruptions, particularly in Victoria where one is overdue, a Melbourne geologist has warned. Associate Professor Bernie Joyce yesterday said there were about 400 volcanoes across Victoria, including some in the state’s western uplands that could erupt at any time, potentially devastating the land around them and claiming lives.

Prof Joyce warns that in north Queensland new volcanoes have erupted ‘perhaps every 2000 years in the past 40,000 years—and given there has not been a major eruption there for the past 5000 years, a significant eruption seems well overdue’. Australian emergency authorities need to be better prepared, he argues, taking a lead from the kind of emergency preparation, public education and information systems seen in New Zealand.

Some of Prof Joyce’s work on volcanic risks in south-eastern Australia and links to related resources can be found here, while a wider discussion of Australian volcano hazard issues is available from the remarkably comprehensive and informative website for the town of Romsey, Victoria.

[Illustration: ‘Mount Gambier, Middle and Valley Lake Craters’, from Julian Edmund Tenison Woods, Geological Observations in South Australia: Principally in the District South-East of Adelaide (London: Longman, Green, Longman, Roberts, & Green, 1862), facing page 230. Available via the Internet Archive.]

News
Volcano eruption ‘overdue’The Age, 21 September 2009
Australian eruption ‘overdue’ – Science Alert, 21 September 2009
Volcano warning: Australian eruption ‘overdue’ – ABC, 21 September 2009
Volcano: we’re 5000 years overdueThe Australian, 21 September 2009

The Volcanism Blog

Comments

1. Beano - 21 September 2009

There is a hotspot offshore south of the mainland between the southern states of Victoria and Tasmania. The Australian continent is drifting northeastwards at a rate of 7cms per year – 7 metres per century.

I would suggest that there would be more likely a damaging earthquake in Australia before more Volcanic activity.

One only needs to drive down the nearly 4000 kilometer long eastern Great Dividing Range to see the countless old volcanic remnants.

Also interesting to note is that a mean tide mark was marked on rock on the south coast of Tasmania in 1841. Allegedly the sea level has risen an average of 1mm a year since then however with the continent shift of 7cms per year any deviation is arbitrary.

The great western Victorian Volcanic plain is dotted with cones. very impressive when you know what you are looking at.

Some reports put the last activity at Mt Elephant or Mt Napier in theVictorian western field as little as 600 years BPE

2. Gijs - 22 September 2009

Pretty much the same thing is going on in the Eifel region in Germany. There hasn’t been an eruption in the area for 9.500 years, where quaternary volcanism started to occur around 970.000 ± 100.000 years BP.

The Eifel can be divided into three volcanic areas. The West Eifel (240 monogenetic volcanoes since ± 970.000 years ago), the Hocheifel (± 300 volcanoes mostly from between 46 million and 6 million years ago), and the East Eifel (± 100 mostly monogenetic volcanoes that formed between ± 500.000 and 11.000 years ago, including the famous Laacher See volcano). To the East and Northeast are other volcanic areas close to the Eifel, all of tertiary age.

– Map of the Eifel region: http://img508.imageshack.us/img508/7049/overzichtskaarteifelsie.png

Currently the Eifel region is relatively quiet. CO2 emissions are low, but in some places visible, like at the ‘cold water geysers’ of Wallenborn and Andernach, and the ‘mofetten’ at the eastern shore of the Laacher See. The uplift of the Rhenish Massif (on which the Eifel is located) is about 1 mm a year, and the area with the most significant seismic activity is located between 50 and 80 kilometres from the Eifel volcanoes, in a graben system that lies to the North (the Aachen and Düren region). Micro earthquakes occur a lot just Southeast of Laacher See, but they’re probably caused by ground water that’s being heated over an area where there is a higher degree of partial melting. No signs of rising magma have ever been recorded, nor anything else happened that indicated impending volcanism or related threats.

– ‘Cold water geyser’ in Wallenborn: http://www.geographie.ruhr-uni-bochum.de/ag/landscha/Wallende_Born.JPG
– ‘Mofetten’ at the Eastern shore of Laacher See: http://static.panoramio.com/photos/original/17279049.jpg
– Micro earthquakes Southeast of Laacher See: http://www.spiegel.de/img/0,1020,800872,00.jpg

The cause of all this is probably an anomaly, of which some think that it is a mantle plume. That it probably isn’t, doesn’t change the fact that the anomaly is still present underneath the Eifel, like it has been for hundreds of thousands of years, if not millions of years. This is one of the main arguments for geologists to think that the area is probably only dormant, and not extinct. That, and ofcourse the fact that volcanism took place there only 9.500 years ago. What’s also interesting to look at, is that there have been some ‘breaks’ in volcanic activity in the past, which lasted between 10.000 and 20.000 years on average.

To make the subject somewhat more popular, geologist Ulrich C. Schreiber wrote a book, called ‘Die Flucht der Ameisen’ (Escape of the Ants), discribing the events leading up to a fictive future eruption in the Eifel, the eruption itself, and the aftermath. Although it didn’t make the headlines everywhere in Europe, it did in Germany, and more people are now aware of what threats volcanism in the Eifel might pose in the future.

Sources:
– ‘Geologie der Eifel’, Wilhelm Meyer
– ‘Volcanism’, Hans-Ulrich Schmincke
http://www.mantleplumes.org/WebpagePDFs/Europe.pdf
http://www.geokalypse.shayol.de/


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