Volcanoes can sing too, it turns out, and the harmonies created by eruption-related earthquakes give key insights into the inner workings of eruption cycles.

Volcanoes can emit their own version of music as magma is pushed up through the cracks in the Earth, but it's the flurry of earthquakes that can precede an eruption that has one group of scientists interested. These small earthquakes range in magnitude from 0.5 to 1.5 and increase in frequency before the eruption, creating a harmonious blend of tremors.

By looking at the Alaskan volcano Redoubt's March 2009 eruptions, researchers were able to form a theory as to why the frequency of earthquakes increases, then pauses, just before the volcano erupts.

"Because there's less time between each earthquake, there's not enough time to build up enough pressure for a bigger one," said Alicia Hotovec-Ellis, a doctoral student at the University of Washington. "After the frequency glides up to a ridiculously high frequency, it pauses and then it explodes."

"We think the pause is when even the earthquakes can't keep up anymore and the two sides of the fault slide smoothly against each other," Hotovec-Ellis explained.

These earthquakes emit sounds that can sound like musical instruments - only their frequencies are often too low to hear. Redoubt, however, surprised the scientists.

"The frequency of this tremor is unusually high for a volcano, and it's not easily explained by many of the accepted theories," Hotovec-Ellis stated.

Interested parties can listen to a one-minute condensed recording of one hour of 1,600 small earthquakes that preceded the first Redbout eruption here.

The full published study can be found in the Journal of Volcanology and Geothermal Research.