Volcanologists have recorded thunder from a volcanic eruption for the first time.
Observers dating back to the ancient Romans have seen lightning in volcanic-ash clouds, but thunder has been much harder to detect — probably because it is masked by other sounds from the explosive eruptions.
Matthew Haney of the US Geological Survey Volcano Science Center in Anchorage, Alaska, and his colleagues used microphones to monitor the Bogoslof volcano in Alaska. Even though the detectors were 60 kilometres from the volcano, they were able to pick up thunder caused by two explosive eruptions in March and June 2017.
The thunder rumbled both audibly and at a frequency too low for the human ear to hear. Both frequencies were easiest to detect near the end of the events, when eruption noise was waning.
Scientists might be able to explore the dynamics of volcanic eruptions by monitoring thunder, the authors say.