Scientists Record Sounds In The Mariana Trench | Ocean’s Deepest Point Is Noisy!
The Mariana Trench is known for being the deepest place on Earth. But recently, scientists discovered something surprising—it’s far from quiet. Using a special device called a hydrophone, researchers from Oregon State University and the National Oceanic and Atmospheric Administration (NOAA) captured the sounds in the trench’s deepest spot, known as Challenger Deep. What they found was an unexpected variety of noises, from natural events like earthquakes and whale calls to human-made sounds like passing ships.
The goal of their research was to understand the baseline noise levels in the ocean. Especially focusing on how human activity might be affecting marine life. But as they began analyzing the recordings, they realized that even at nearly 36,000 feet below the surface, the ocean is filled with sound. Let’s have a closer look.
Deep Down In The Mariana Trench
The Mariana Trench is located near Micronesia and is a subduction zone, where tectonic plates collide. This collision creates significant seismic activity, making it one of the most geologically active areas on Earth. The trench itself is the deepest canyon on the planet. To give you an idea of just how deep it is, if Mount Everest were placed inside the trench, its peak would still be over a mile underwater.
“This should be one of the quietest places in the world, but it was a lot noisier than we expected. There really is almost constant sound from natural and man-made sources.”
Oregon-based oceanographer Robert Dziak, who led the project for the National Oceanic and Atmospheric Administration (NOAA).
Few expeditions have ventured to these depths. One of the most famous was filmmaker James Cameron’s solo dive in 2012. He spent two hours at the bottom of Challenger Deep in a custom-built submarine. Reaching these depths is a massive challenge due to the extreme pressure and cold temperatures. This study marked one of the first times scientists successfully recorded sound at such depths.
The hydrophone used for this project was specially designed. It can withstand the immense pressure—up to 16,000 pounds per square inch. It was encased in titanium nearly an inch thick. The researchers knew that even the slightest flaw in design would cause the device to be crushed. Oregon State University engineers Haru Matsumoto and Chris Meinig, from NOAA’s Pacific Marine Environmental Laboratory, were the brains behind this impressive piece of equipment.
“It’s not an easy thing to do to get an instrument package to the seafloor, recover it from that depth and have it survive. We had never put a hydrophone deeper than a mile or so below the surface.”
Oregon State University engineer Haru Matsumoto and Chris Meinig, of NOAA’s Pacific Marine Environmental Laboratory in Seattle
Scientists Record Sounds In The Mariana Trench
Whale Calls at Unimaginable Depths
The hydrophone picked up something unexpected—whale calls. Normally, whales don’t dive deeper than about a mile. However, their vocalizations traveled all the way to the bottom of the trench. A baleen whale’s call, sounding like a foghorn, echoed through the depths. Another recording captured the deep-pitched sounds of a toothed whale or dolphin. It sounded like a “muffled thunder.” The scientists were surprised by the level of conversation happening between these marine mammals. It is far deeper than anyone had anticipated.
Earthquake Activity Recorded
Since the Mariana Trench is located in a seismically active area, the hydrophone frequently recorded earthquakes. The sounds of these quakes build up in intensity, much like an approaching train. This natural rumbling is a regular occurrence in the trench due to the movement of tectonic plates.
Typhoons Overhead
One of the most powerful recordings came from a Category 4 typhoon that passed over the trench. The storm raged nearly 200 miles north of the trench’s location. However, the hydrophone clearly captured the roar of high winds and big waves crashing on the surface. The energy from the storm was so intense that it made the entire basin noisy.
Ship Traffic
Despite the trench’s remote location, the hydrophone picked up the sounds of ships passing near the island of Guam. It is on a major transoceanic route. The sound of propellers from ships 6.7 miles away was clearly recorded. The rhythmic, high-pitched noise from these vessels was almost constant. This shows just how much human activity affects even the deepest parts of the ocean.
The Tech Behind the Discovery
Creating a hydrophone capable of withstanding the extreme conditions in Challenger Deep was no small feat. The 20-inch-long device was carefully crafted from titanium to handle the crushing pressure of the deep ocean. They had to lower it to the seafloor over a six-hour period to avoid damaging it with rapid pressure changes.
Once on the seafloor, the hydrophone stayed in place for 23 days, recording continuously. It was anchored about 20 feet above the soft ocean bottom to ensure that it captured the full range of sounds. After the recording period, scientists sent an acoustic signal to trigger a release mechanism, allowing the hydrophone to float back to the surface.
The U.S. Coast Guard cutter Sequoia, based in Guam, assisted the researchers with the deployment and retrieval of the hydrophone. The entire process highlighted just how difficult it is to conduct research at such extreme depths.
Noise Pollution Even in the Deepest Oceans
Global Noise Pollution
One of the most significant takeaways from this research is that man-made noise reaches even the most remote corners of the ocean. Ship traffic, in particular, seems to affect the noise levels in the trench, despite its incredible depth. This finding is part of a broader effort to map global ocean noise and understand how it affects marine life.
Effects on Marine Life
The impact of all this noise on marine life, particularly deep-sea creatures, is still not fully understood. Marine mammals like whales are known to be sensitive to sound, so the constant barrage of human-made noise could potentially disrupt their communication and behavior. More research is needed to understand how creatures that live in the trench, many of which are adapted to the dark and quiet, are coping with this intrusion of sound.
Conclusion
The Mariana Trench, especially Challenger Deep, is not the quiet, isolated place scientists once thought. Instead, it’s filled with sounds from whales, earthquakes, typhoons, and even passing ships. The discovery highlights the surprising reach of man-made noise and its potential effects on marine life. This research shows just how much we still have to learn about the deep ocean. Continued exploration and monitoring are crucial not only for satisfying our curiosity about these mysterious environments but also for protecting them from the growing threat of noise pollution.
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