It sounds like a joke: what did the volcano say just before it blew its top?
As it turns out, it didn't actually say anything, but instead screamed like a banshee.
University of Washington scientist Alicia Hotovec-Ellis, a doctoral student in Earth and Space Sciences, recorded audio of Alaska's Redoubt Volcano during a 2009 eruption.
She wanted to know what happens moments before a volcano erupts.
As it turns out, a number of small earthquakes, ranging in magnitude from about 0.5 to 1.5. As the pressure builds, the quakes get smaller and happen in such rapid succession that they blend into a continuous harmonic tremor.
"After the frequency glides up to a ridiculously high frequency, it pauses and then it explodes," she explained.
And it sounds like a really intense drum circle...at first.
So what's the point of all of this? Possibly a precursor to creating devices that warn people of a pending eruption, thus saving lives.
Or just take notice when all the animals scurry away.