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Possible new trigger for volcanic eruptions discovered.

New findings published in the journal Earth and Planetary Science Letters will add to our understanding of how volcanoes function. The research will also be intertwined with satellite, seismological and ground deformation data which collectively show the movement of magma within a volcano. The data obtained from this new research will specifically help volcanologists understand what happens to magma when it ascends through an active volcano.

Scientists from the University of Newcastle in Australia, the University of Liverpool in the UK and Monash University in Melbourne have improved our understanding of how volcanoes erupt. According to the international team of researchers, understanding the triggers for volcanic eruptions will widen the scope of data interpretation and therefore allow volcanic eruptions to be better predicted.

This is no trivial matter as over 600 million people (about 10% of the global population) live near one form of active volcano or another. The hope is that after discovering the new triggering mechanism that forecasting will become more accurate, risk will be reduced and more time for preparation be gained. The economic impact of volcanic eruptions can be profound. In 2010 the Eyjafjallajokull volcano erupted and European air travel was severely disrupted. The travel plans of millions were ruined and the airline industry lost almost $2billion in turnover. However, nobody was killed or displaced and emergency humanitarian aid was not necessary.

Without doubt the job of a volcanologist is one of the most challenging and dangerous occupations in existence. To reduce the danger and concurrent logistical difficulties that are the lot of the modern volcanologist, detailed scale models were built in the labs of Monash University. These models reveal that as magma ascends through the fault lines (the sills and dykes) inside an active volcano the physics of lava movement changes.

Sills form as horizontal fault lines and when fluids travelling in a vertical fault line (a dyke) come into contact with sills profound pressure changes occur. Researchers at Monash University used a matrix of jelly and water to mimic the processes which occur in an active volcano. In essence when the fluid ascending in the model sills comes into contact with a dyke, there is a marked drop in pressure. The pressure drop forces the fluid to release bubbles of dissolved gas. It is the release of these gases that is the hypothesized and hitherto undiscovered trigger for some eruptions.

The process in analogous to shaking a sealed carbonated drink bottle (or can) and then opening the cap or seal. The rapid drop in pressure causes bubbles of carbon dioxide gas to form which adds to the volume of the fluid, producing foam which is expelled from the container.  Currently, eruption prediction is anything but an exact science, we simply do not understand enough about the geophysics inherent to the study of volcanoes.

This new strand of research will hopefully lead to improvements in our ability to predict both the occurrence and frequency of eruptions.

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