For the first time ever, the ominous rumble of volcanic thunder has been recorded. Produced my lightning within the ash clouds of a volcanic eruption, those who have had occasion to witness this phenomenon have described the sound as a thunder-like “boom” from the heavens.
It has been difficult for scientists to differentiate volcanic thunder from other sounds in the cacophony of a volcanic eruption, which includes the roar of hot gases, bubble blasts bursting, shock wave booms, and so on, Science Alert reports.
In December 2016, the Bogoslof volcano in the Aleutian Islands in Alaska started rumbling, and scientists at the US Geological Survey listened intently. They positioned microphones on a nearby island to capture the upheaval, which lasted for eight long months. The team then listened back to the recordings, and were able to isolate several cracking sounds, which are the signature of volcanic thunder.
The scientists published audio clips from the volcanic eruption, which was sped up to reveal the loud cracks and pops of volcanic thunder in the midst of the actual rumbles from the eruption.
Matt Haney, lead author on the study and a seismologist with the USGS and the Alaska Volcano Observatory, said in a news release,
If people had been observing the eruption in person, they would have heard this thunder.
Several of the Bogoslof volcanic eruption plumes spewed thousands of feet up in the sky, interfering with air travel.
Haney and his colleagues wrote that thunder signals took place at the same time as lightning signals from the eruption. In the future, thunder can be used as a proxy to study volcanic lightning, which happens in charged particles among the ash clouds.
Haney said, “I expect that going forward, other researchers are going to be excited and motivated to look in their data sets to see if they can pick up the thunder signal.”
The findings were published in Geophysical Research Letters.