It is often said that screaming in the mountains can cause avalanches… but is it really like that? Actually no, it’s one fake news strengthened by many scenes from films, cartoons and comics. To understand something more, simply quote the study “Avalanche triggering by sound: myth and truth” published in 2009 by a team of Swiss researchers who deal with avalanches and their trigger mechanisms.
The first concept to clarify is that every sound produces apressure wavemeasured in pascal (Pa). Below is a table which summarizes some sources with their respective pressure wave values:
| Source | Pressure wave |
|---|---|
| Human scream | 2 Pa |
| Airliner | 2nd Pa |
| Sonic boom | 200 Pa |
| Explosive detonation | >1500 Pa |
As we can see the human scream is at the bottom of the ranking with an average of 2 pascals. Are there many? Are they few?
We consider that – as confirmed by the authors of the study – to ensure that there is a structural failure within an already compromised snow mass, a pressure wave of at least 200-500 pascals. If, however, conditions are more stable, this value will be proportionally higher.
From here we clearly see how the human voice is at least two orders of magnitude less than the minimum threshold necessary to give rise to an avalanche and, consequently, we can affirm that it is mainly a myth with no scientific basis. As also reported by the authors:
In periods of strong instability, when natural avalanches are often observed, a coincidence between shouting and release may occur, but it will not be possible to say that the release was caused by shouting.
