When volcanoes erupt, they often do so thunderously. But until recently, scientists have been unable to distinguish the sounds of an eruption from the sounds of volcanic thunder.

In addition to the loud roar of eruptions, lightning strikes that spring from volcanic plumes create loud claps of thunder.

Now, in new audio clips published in the Geophysical Research Letters, scientists are revealing the first recordings of the phenomenon.

The crackling sound was identified using microphones set up to detect eruptions coming from Bogoslof volcano in Alaska’s southwestern Aleutian Islands. Over an eight-month period, the microphones picked up a mixture of eruption booms and lightning cracks. Only by cross checking a map of volcanic lightning were they able to distinguish what on the