Upsweep

Common card · No. 485679

The Upsweep is a sound detected by the U.S. National Oceanic and Atmospheric Administration's (NOAA) equatorial autonomous hydrophone arrays. The sound was recorded in August 1991, using the Pacific Marine Environmental Laboratory's underwater sound surveillance system, SOSUS, and is loud enough to be detected throughout the entire Pacific Ocean. By 1996, early speculation that the sound originated from a biological source was dismissed. The sound consists of a long train of narrow-band upsweeping sounds that occur in intervals of several seconds each. Upsweep occurs and changes seasonally, and is therefore speculated by NOAA scientists to originate from areas of underwater volcanic activity.

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