The NOAA, or National Oceanic and Atmospheric Administration, has been recording sounds near the seabed of the Pacific Ocean with advanced hydrophones since the early 1990’s. What initiated as a way to track Soviet Submarine activities has since morphed into an umbrella project for the monitoring and archiving of undersea seismic activity, as well as capturing noises created by nearby sea life. Since the program’s inception, a still-unidentified noise, dubbed “Upsweep,” has puzzled and captivated the minds of the organization and the public at large.
“Upsweep,” named after the cycle of upsweeping sounds that repeat with varying levels of frequency, was initially thought to originate from submarine activity between the regions from New Zealand to the western seaboard of South America. Researchers now suspect, however, that the noise instead emanates from intense and oscillating volcanic activity on the ocean floor below. While it’s precise location is located near suspected volcanic activity, the true source of the sound remains unsolved.
Interestingly enough, the sound’s output, volume, and frequency all experience seasonal change, heightening in the fall and spring periods, while quieting down considerably in the winter and summer. While its overall volume has declined since the 1990’s, it’s output and seasonal variance still remains and continues to be tracked on the NOAA’s hydrophone systems.
The oscillating noises themselves offer a sort of eerie comfort. If the source is indeed produced via a natural origin, such as a volcano, it serves as a reminder of the vast expanse of earth’s constantly evolving seafloor, being birthed, collapsed, and again renewed by the volcanism erupting from our planet’s molten mantle.