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There’s a fascinating reason why Everest makes seriously terrifying sounds at night time, which had previously left scientists completely stumped.
Dave Hahn, an expedition leader who has completed 15 Everest summits, spoke about what it felt like hearing the bizarre noises in a recent Netflix documentary, Aftershock: Everest and the Nepal Earthquake.
In the three-part docuseries, which includes survivors’ first-hand accounts and actual footage from the deadly earthquake that hit Nepal in 2015, Hahn reflects on his experiences on Everest that fateful year.
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At one point, he explains how hard it can be to sleep at night - and not just because of the apprehension of climbing a huge mountain.
“It's tough to sleep,” he says.
“There’s all this anticipation and you can hear the glacier that you’re sleeping on - and that you’re going to climb through - you can hear it popping, you can hear ice and rock crashing down in various places around the valley.”
Indeed, the strange, eerie sounds come from the glacier itself, and it turns out there’s also a reason why it happens at night.
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Back in 2018, a study into the phenomenon was published in the journal Geophysical Research Letters, which explored how these booming noises became more intense when temperatures dropped at night.
Evgeny Podolskiy, a glaciologist at the Arctic Research Center in Hokkaido University, Japan - and lead author of the paper - said: "Local ice turns out to be very sensitive to this high rate of change.”
Podolskiy and his team had trekked through the Nepalese Himalayas the year before to test the seismic activity of the Trakarding-Trambau glaciers, travelling to a one about 5km above sea level, in full view of Mount Everest.
While he said the experience was ‘amazing’ as it was such a ‘magnificent’ area to work in, after dark the researchers became unnerved after hearing bizarre sounds coming from the glacier.
"We hear this loud boom," Podolskiy recalled.
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"We noticed that our glacier is bursting, or exploding with cracks at night."
While they couldn’t see what was happening, during the three weeks they spent listening to the noise, they began to wonder if there was a reason why they tended to hear it at night - suspecting the booming sounds may have had something to do with temperature changes.
After studying seismographic data, they discovered that there were abrupt nightly temperature drops due to the glacier's high altitude, which was what was causing the noises.
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