For periods ranging from hours to weeks before all explosive volcanic eruptions, the ground is shaken by tremors that have a remarkably consistent range of frequencies. Despite these tremors being observed by scientists all over the world, the underlying mechanism for their creation has never been explained.

In a paper published in Nature, the UBC scientists describe a model that is based on physical properties that most experts agree are common to all explosive volcanic systems, and applies to all shapes and sizes of volcanoes.

‘All volcanoes feature a viscous column of dense magma surrounded by a compressible and permeable sheath of magma, composed mostly of stretched gas bubbles,’ explained the study’s lead author, Mark Jellinek. ‘In our model, we show that as the centre “plug” of dense magma rises, it simply oscillates, or “wags”, against the cushion of gas bubbles, generating tremors at the observed frequencies.’

The scientists suggest that the new model may help experts to predict eruptions more accurately. ‘Because our model is so universal, it may have significant predictive power for the onset of eruptions that are dangerous to humans,’ Jellinek said.

April 2011