12 December 2006

A University of Queensland scientist has developed a computer model that could help provide more accurate predictions about volcanic eruptions.

Dr Alina Hale, from the University’s Earth Systems Science Computational Centre, has been investigating a type of repetitive earthquake known as a long-period (LP) event, which often precedes changes in volcanic activity.

While the source of these LP earthquakes was not previously understood, scientists now think that areas of instability in volcanic lava flow, called shear bands, might be the trigger.

However, Dr Hale said that until now, no scientist has been able to establish an accurate correlation between the presence of the shear bands and LP earthquakes.

“To date, no model has convincingly simulated shear bands to the depths at which LP seismicity occurs,” she said.

Dr Hale developed a computer model to address this deficiency, incorporating processes such as the formation of crystals and pressure-sensitivity in lava to make the correlation more precise.

Using data from the Soufrière Hills Volcano, which devastated the island of Montserrat in the West Indies in the late nineties, Dr Hale was able to show that shear bands can form at the depths required for LP seismicity.

“In addition to this, model results provide an explanation for observed pressure oscillations within the volcano as well as changes in the extrusion rate, due to the formation of shear bands,” she said.

Dr Hale said that these results bring scientists closer to being able to better predict eruptions across the world.

“Evidence of LP seismicity is not only observed at the Soufrière Hills Volcano but at numerous other volcanoes including Kilauea, Hawaii; Shishaldin Volcano, Alaska
and Galeras Volcano, Colombia,” she said.

“This has implications for forecasting volcanic eruptions because we now have a greater understanding of the source mechanism and the surrounding magma properties.

“Within any given year there are approximately 30 eruptions and there have been over 60,000 deaths due to volcanoes, so any advances in this field are significant.”

Dr Hale said the unique resources of the University’s Earth Systems Science Computational Centre enabled her to perform this research.

She was recently awarded an Australian Postdoctoral Research Fellowship from the Australian Research Council’s Discovery Grant Scheme to further this area of research in collaboration with scientists from UQ, the UK and Russia.

Media: Further information, contact Lucy Manderson, telephone 07 3365 2339 or Dr Alina Hale, telephone 07 3346 4110. Photos available.