Posted by: The ocean update | March 22, 2016

Sounds of the deep : first recordings from the deepest point on Earth (Mariana Trench)

ChallengerDeepMarch 22nd, 2016. From moans of whales to the put-put-put of ships’ propellers, from the rumble of earthquakes to the roar of typhoons : scientists release first recordings from the deepest point on Earth.

Last July, an underwater microphone was lowered into the Challenger Deep, the deepest point in the Mariana Trench, the 2,550-km-long and 70-km-wide trough on the Pacific Ocean floor to the east of the Philippines, the deepest part of the world’s oceans. The scientists, from the US National Oceanic and Atmospheric Administration, Oregon State University and US Coast Guard, had expected a deep silence; instead, they heard a cacophony of sounds, both natural and created by humans.

The NOAA-funded project was intended to establish a baseline for ambient noise in the Pacific’s deepest part. Human-created noise has increased steadily in recent decades, and scientists in the future need data to determine how this might affect marine animals that use sound to communicate, navigate and feed — whales, dolphins and fish. The hydrophone stayed underwater for about 3 weeks; the next mission, in early 2017, will deploy it for longer, and also attach a deep-ocean camera.

The Site

Challenger Deep is at the southern tip of Mariana Trench, near Micronesia, close to the US island territory of Guam, the regional hub for US container shipping with China and Philippines.

Below are some of the strange sounds that came back, including whales calls, which are made by a mix of baleen and toothed (odontocete) whales :

Here’s what it sounds like when a boat passes 10.9 km (6.7 miles) over your head :

And here’s a magnitude 5 earthquake rumbling near Guam on 16 July 2015 :

This is a baleen whale’s calls right before and after the same quake :




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