1. "Bloop"
And if the evidence of a certain "groan" of the Earth does not seem so reliable, then low-frequency sound from the bowels of the ocean was recorded several times by the National Oceanic and Atmospheric Administration (NOAA) in the summer of 1997. The sound was called bloop (English "howl, roar"). The geographical coordinates of the sound are 50 degrees S. and 100 degrees W. (southwest of South America). The general nature of the sound made it possible to put forward the assumption that its source is a living being. Such a creation, however, is unknown to science. Based on the distance traveled by the sound, the creature should be simply gigantic. Much larger than the blue whale - the largest animal currently living on the planet. Another option: it can be clusters of large animals, for example, giant squids. The scientific community, however,due to the unprovability of these versions, they quickly abandoned them in favor of a more likely shaking of ice fields or icebergs scraping along the bottom.
Bloop sound spectrogram.
An interesting fact: the coordinates of the "bloop" are approximately 2000 km from the very place that the American science fiction writer Howard Lovecraft called the underwater abode of Cthulhu.
2. "Quaker"
Something similar is sometimes recorded by the echolocation installations of sea vessels. The first described cases date back to the 1970s. The peak of reports of low-frequency sound vibrations (many of which are similar to the croaking of a frog - hence the name) occurred in the 1975-1980s. But after 1990, no one heard the "Quaker". At least there is not a single officially reported case.
This is associated with the end of the Cold War between the USSR and the West, which led to the weakening of naval intelligence. But the Quaker was first "spotted" not by anyone, namely by the Soviet Navy, who suggested that the enemy had deployed a global direction finding system for sea vessels. As a result, the "axis of evil" allegedly even organized the "Quaker" program, which studied this problem until the 1980s. After that, it was allegedly folded and sent to the archives under the heading "Secret".
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Basilosaurus.
And again, one of the versions of the source of strange sounds was reduced to the existence of some huge animal, unknown, most likely, to science, or even extinct animals like basilosaurs (ancient giant whales that lived 45-36 million years ago). Other researchers, however, argued that the sounds are emitted by the same giant squid or some species of cetaceans, which are known to be excellent at using hydroacoustics.
3. Fifty-two hertz whale
Another "NGO". Rather, identified, but not caught. This is the name of a certain individual of an unknown species of whale, which has been regularly tracked in various parts of the ocean since the 1980s. The name of the whale comes from its extremely unusual singing at a frequency of 52 Hz - lower than the lowest note on a tuba. This is a much higher frequency than that of the blue whale (15–20 Hz) or the second largest animal on the planet, the fin whale, a close relative of the blue whale (20 Hz). None of the cetaceans recorded such singing, so the elusive animal was even called the loneliest whale in the world.
Analysis of the sound allows us to establish that the song seems to be unambiguously published by a whale, but who he is is a mystery to this day. Its routes are not related to the presence or movement of other whale species. The animal is found in the Pacific Ocean annually from August to December; it leaves the range of hydrophones in January-February. The whale swims north to the Aleutian Islands and the Kodiak Archipelago south to the California coast, covering 30 to 70 km per day. The recorded distance covered by the whale during the season ranged from 708 to 11,062 km (data for 2002-2003).
Scientists speculate that the whale may be a mutant or hybrid of a blue whale and another species, and indeed is the loneliest whale on the planet, as it literally exists in one instance.