Underwater sound could help pinpoint ocean impacts

A hydrophone node is lowered into the water (Credit: CBTO via CC)

The method involves underwater microphones known as hydrophones. These can accurately measure acoustic gravity waves (AGWs) - naturally occurring sound waves that move through the deep ocean at the speed of sound. AGWs can measure tens of kilometres and travel vast distances, and are also generated when large objects hit the ocean surface, caused by the sudden change in pressure.  As well as potentially tracking the entry points of meteorites and falling satellites, the technique could be used to locate stricken aircraft such as the Malaysian Airlines Flight MH370.

The Cardiff team first tested the method in the lab, dropping spheres into a water tank from various heights and measuring the results with a hydrophone. It later used existing hydrophone data from off the coast of Western Australia to accurately calculate the time and location of recent earthquakes that had occurred in the Indian Ocean. The research appears in the journal Scientific Reports.