Listening To Volcanoes

Volcanoes are complicated, and we don’t have universally applicable ways to predict when they might erupt.  Measurements of seismicity, gas emissions and ground deformation are all useful in trying to figure out what volcanoes are up to.  However, it is unlikely that will ever have definitive prediction techniques.

That doesn’t mean that we are not getting better at predicting volcanic activity.  A new study by Stanford and Boise State University scientists has shown that monitoring inaudible low frequencies called infrasound by some kinds of volcanoes could improve the forecasting of significant eruptions.

The scientists analyzed the infrasound detected by monitoring stations on the slopes of the Villarrica volcano in southern Chile.  It is one of the most active volcanoes in the world.  The sounds come from the roiling of a lava lake inside a crater at the peak of the volcano.  The sounds change depending on the volcano’s activity.

The study showed how changes in these sounds signaled a sudden rise in the lake level along with rapid motions of the lava just ahead of a major eruption in 2015.   This was done after the fact but tracking infrasound in real time and integrating it with other data might enable authorities to alert nearly residents and tourists that an eruption is forthcoming.

Volcanologists think that changes in lava lake levels results from the injection of new magma through the volcanic plumbing, increasing the odds of a violent eruption.  So collecting infrasound data should prove beneficial in forecasting the behavior of so-called “open vent” volcanoes like Villarrica, where an exposed lake or channels of lava connect the volcano’s innards to the atmosphere.  Closed vent volcanoes, like Mount St. Helens in Washington state, unfortunately do not produce the same kind of infrasound.

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Stanford scientists eavesdrop on volcanic rumblings to forecast eruptions

Photo, posted November 22, 2016, courtesy of Travelers Travel Photobook via Flickr.

‘Listening to Volcanoes’ from Earth Wise is a production of WAMC Northeast Public Radio.