In 1997, while searching for underwater volcanic activity in the Southern Pacific, a team of scientists recorded something that can't be explained. They heard a strange, powerful, and deafening sound with ultra-low frequency.
What is 'The Bloop'?
The noise is one of the loudest sounds ever recorded under the sea. Not only is it loud, but the sound also had a unique characteristic that came to be known as 'The Bloop.' Underwater microphones called hydrophones positioned more than 3,000 miles (4,828 kilometers) apart captured numerous instances of this noise.
Experts from the Pacific Marine Environmental Laboratory (PMEL) of the National Oceanic and Atmospheric Administration (NOAA) were the first to record the Bloop. However, they found it hard to trace the origin of the sound since 95% of the ocean remains unexplored.
According to NOAA acoustics program manager Bob Dziak, it is unusual for a sound to be recorded on all of the sensors that have been deployed. If a ship or a whale produced sound in the ocean, it would not be big enough to be recorded across the Pacific.
Origin of the Strange Sound
The Bloop captured the imagination of people all around the world. There is a theory that this noise results from underwater erupting volcanoes, but such landforms may not be able to produce such a strange frequency.
Another theory suggests that this sound was the call of an aquatic dinosaur, a megalodon, or a huge, undiscovered marine mammal. These theories became more intriguing when NOAA reported that the sound was not man-made but possibly biological.
It has been argued that the patterns in the variations within the sound indicate an animal origin. Referring to similar sound-making capabilities of a blue whale, the largest known animal species, the Bloop would have to be emitted by an animal over 250 feet (76 meters) long.
Others also pointed out that not all animals make the same amount of noise for their size. For instance, the pistol shrimp can make sounds as loud as a jet engine, even if it measures only a few centimeters long. Considering this argument, the animalmakings the Bloop noise might be significantly smaller than generally estimated.
In 2012, the NOAA determined that the Bloop is consistent with the noises emitted through non-tectonic cryoseisms originating from glacial movements. These include icequakes generated by large icebergs scraping the ocean floor.
The sound source was located off the tip of South America and was detected several times by the Equatorial Pacific Ocean hydrophone system. It was developed as an autonomous array of underwater microphones that can be deployed in any oceanographic region for monitoring specific phenomena. This stand-alone system is also used primarily for monitoring ice noise, undersea seismicity, and marine mammal population and migration.
In 2014, it was proposed that the Bloop was the sound of the sea created when ice breaks off the Antarctic ice shelf. Finally, in 2023, it was confirmed that the Bloop is a sound made by glacier ice.
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