Model to help predict volcanic eruptions

February 24th, 2011 - 6:38 pm ICT by ANI  

London, Feb 24 (ANI): A model developed by the researchers at Yale University and the University of British Columbia may help forecast deadly volcanic eruptions.

No matter their size or shape, explosive volcanoes produce tremors at similar frequencies for minutes, days or weeks before they erupt.

Now, researchers have described a model that explains this strange phenomenon.

Prior to most explosive eruptions, the erupting volcanoes shoot hot ash up to 40 km high, shake slightly but measurably, and the shaking becomes more dramatic during the eruption itself - a primary precursor used by vulcanologists for forecasting an eruption.

“Tremor is very mysterious, most notably because it shakes at pretty much the same frequency in almost every explosive volcano, whether it’s in Alaska, the Caribbean, New Zealand, or Central America,” said Yale geology professor and co-author David Bercovici.

“That it’s so universal is very weird because volcanoes are so different in size and character. It would be like blowing on five different musical wind instruments and having them all sound the same,” he added.

For minutes to weeks before eruptions, tremors in nearly all volcanoes stay in a narrow band of frequencies from about 0.5 to 2 Hz.

Just before and during the eruption, the frequency climbs to a higher pitch, and the range spreads out between 0.5 and 7 Hz.

Bercovici and his colleague Mark Jellinek at UBC suggested that these similarities can be explained by ‘magma wagging’, or the rattling that occurs from the interaction of rising magma and the foamy jacket of gas that surrounds it.

The factors that control this rattling or wagging vary little between volcanoes, which explains why the same tremors occur in very different volcanoes, they said.

“This model will provide a much-needed framework for understanding the physics of tremors, and this can only help with the prediction and forecasting of destructive eruptions,” said Bercovici.

The study has been published in Nature. (ANI)

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