2 weeks Ago By Isaac Schultz
What do the Costco Guys and the Hunga Tonga-Hunga Ha’apai volcano have in common? They both bring the boom, as evinced by a recent study of the latter’s noise when it blew its top. The huge eruption roiled the Pacific Ocean in January 2022, generating shock waves through the air, tsunamis across the sea, and spewing a cloud of ash and debris 25 miles (40 kilometers) into the sky. The eruption destroyed the volcanic island, and according to a new study, the intensity of the remote event unnerved people from Alaska to New Zealand—and even Germany.
Within a week of the eruption, a research team distributed a 39-question survey to collect data on the audible characteristics of the eruption. They collected nearly 2,000 responses that reveal the eruption’s volume across New Zealand and how that sound was experienced by the affected population. The team, from GNE Science—a state-owned research institute— published its findings earlier this year in Communications Earth & Environment .
People around the world heard the eruption, but the study was concentrated on New Zealand—relatively close to the Tongan volcano. Respondents’ opinions on what the eruption sounded like ranged from an explosion (according to 37% of people) to a door slamming (9%). Overall, respondents classified the perceived loudness of the eruption as a light (60 decibels) to moderately loud (80 dB) sound.
For comparison, that’s roughly the scale between the sound of a running dishwasher to the bracing ring of an alarm clock. One-quarter of survey respondents said the sound was louder than 90 dB, equating to the volume of a lawnmower and louder. It wasn’t just an auditory experience for some.
“I had never heard/felt anything like them before—most unusual,” wrote one of the survey participants. “Noises my ears heard coupled with a bodily sensation as if I could ‘feel’ the sounds.” Of course, in some places the shock waves of the eruption were such that the sounds could be felt.
“The noises were so loud, our windows and front door shook with each boom,” wrote participant 305. About 5% of survey respondents (40 people) reported animals acting strange just before or after the explosion, indicating they, too, noticed that something intense had just happened. Dogs barked, cats hid, birds crowd, and sheep showed “noticeably unusual behavior”—though the study did not expand on what that meant.
Though the eruption happened nearly three years ago, researchers continue to learn new things about the event. Just last month a different team of scientists found something weird happened 15 minutes before the eruption: A rapidly moving shock wave, called a Rayleigh wave, discovered in data from seismometer stations in Fiji and Futuma, hundreds of miles from the Tongan volcano. “Collective observations of eruption sounds after the 1883 Krakatau eruption, the last eruption known to be heard at extremely long distances from the source (1000’s of kilometers), have similar characteristics to observations of the Hunga eruption sounds, captured ~140 years later,” the study authors wrote.
“Reliable arrival time window estimates, descriptions of rolling ‘boom’ sounds, comparison to guns, and information-seeking behavior emerge in both datasets.” “Although the survey data are uncertain in nature, captured in a context with many human variables and limited calibration or control, they still add value to our understanding of the impact of this event and long-range eruption acoustics,” the authors added. On a bit of a tangent, the survey responses also offer a reminder why commercial supersonic travel over land went the way of the dodo.
That said, NASA is working on an aircraft design that could mitigate the cracking sound into a mere “sonic thump.” This is almost certainly not the last we’ve heard about the Tonga eruption, which is a useful case study of one of the most intense phenomena our planet has to offer. Let’s put it this way: When the Costco Guys bring the boom, just know that the Hunga Tonga-Hunga Ha’apai volcano brings the BOOM.
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