Listening to volcanoes

What is it about?

Active volcanoes produce intense infrasound, or low-frequency sounds below 20 Hz, which may be recorded with specialized microphones many kilometers from a volcanic crater. An objective of volcano infrasound research is to infer volcano source processes, such as explosions, and the modulating influences of topographic effects and atmospheric transmission. This study reports on a novel type of signal recorded at Cotopaxi Volcano (in Ecuador) where the infrasound possesses a remarkably low frequency and reverberates for many tens of seconds. We attribute the form of these infrasound events to the geometry of Cotopaxi’s crater, which is a deep, steep-walled cylinder about 300-m deep and with a diameter of approximately 125 m and acts like a gigantic pipe resonator.

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