Volcanologists at the University of Liverpool have discovered that a process called frictional melting plays a role in determining how a volcano will erupt by dictating how fast magma can ascend to the surface, and how much resistance it faces en-route. (Agencies)
The process occurs in lava dome volcanoes when magma and rocks melt as they rub against each other due to intense heat. This creates a stop start movement in the magma as it makes its way towards the Earth's surface.
The magma sticks to the rock and stops moving until enough pressure builds up, prompting it to shift forward again, a process called stick-slip.
"Seismologists have long known that frictional melting takes place when large tectonic earthquakes occur. It is also thought that the stick-slip process that frictional melting generates is concurrent to 'seismic drumbeats' which are the regular, rhythmic small earthquakes which have been recently found to accompany large volcanic eruptions," said Dr Jackie Kendrick, who led the research.
"Using friction experiments we have shown that the extent of frictional melting depends on the composition of the rock and magma, which determines how fast or slow the magma travels to the surface during the eruption," said Kendrick.
Analysis of lava collected from Mount St Helens, US and the Soufriere Hills volcano in Montserrat showed remnants of pseudotachylyte, a cooled frictional melt.
Evidence showed that the process took place in the conduit, the channel which lava passes through on its way to erupt.
"The closer we get to understanding the way magma behaves, the closer we will get to the ultimate goal: predicting volcanic activity when unrest begins. Whilst we can reasonably predict when a volcanic eruption is about to happen, this new knowledge will help us to predict how the eruption will behave," Kendrick added.
The research was published in the journal Nature Geoscience.
Volcanologists at the University of Liverpool have discovered that a process called frictional melting plays a role in determining how a volcano will erupt by dictating how fast magma can ascend to the surface, and how much resistance it faces en-route.