San Diego’s Mysterious Underwater Sounds Baffle Scientists

In the enigmatic depths of the Pacific Ocean off the coast of San Diego, an auditory enigma has perplexed scientists for decades. Mysterious low-frequency sounds, known as “booms,” have been echoing through the waters, their origin and purpose shrouded in uncertainty.In the enigmatic depths of the Pacific Ocean off the coast of San Diego, an auditory enigma has perplexed scientists for decades. Mysterious low-frequency sounds, known as “booms,” have been echoing through the waters, their origin and purpose shrouded in uncertainty. In the 1960s, hydrophones deployed by the U.S. Navy captured the first recordings of these enigmatic sounds. The powerful booms ranged in frequency from 5 to 25 hertz and lasted for several seconds, resembling underwater explosions. However, investigations failed to identify any obvious sources for the phenomena. Over the years, numerous theories have emerged to explain the San Diego booms. Some scientists have suggested that they are caused by tectonic activity, as the Pacific Plate slides underneath the North American Plate. Others have proposed that they arise from underwater landslides or the movement of large marine mammals. However, none of these hypotheses has been conclusively proven. The location of the booms coincides with the San Diego Trough, a deep underwater canyon, but the exact mechanism that generates the sounds remains a mystery. In 2019, a team of researchers from the Scripps Institution of Oceanography launched a new study to investigate the booms. They deployed hydrophone arrays along the coast and set up acoustic receivers on nearby islands. Their findings, published in the journal “Geophysical Research Letters,” revealed that the booms occur in specific locations, suggesting a localized source. “The booms are not random events,” said lead author Robert Dziak. “They happen in very specific places and at predictable times, which suggests that they are generated by a specific process.” The researchers also found that the booms are associated with the presence of large sand waves on the seafloor. These waves, which can reach heights of over 100 feet, are constantly shifting due to tidal currents. “We think that the booms are caused by the movement of these sand waves,” Dziak said. “As the waves shift, they create friction with the surrounding water, which generates the low-frequency sounds.” While this hypothesis is still being tested, it offers a plausible explanation for the San Diego booms. The sand waves in the San Diego Trough are unique in their size and mobility, which could account for the unusual acoustics of the region. The mystery of the San Diego booms continues to captivate scientists and the public alike. The elusive nature of their origin adds to their allure, making them a testament to the vast and unexplored wonders that lie beneath the ocean’s surface.