In November 2014, scientists from the University of Bath revealed a sonar system called Acoustic Zoom, which is less disruptive to marine life but also improves the resolution of imaging beyond that of current methods.
The most common method currently used when undertaking geological surveys of the seabed is seismic imaging, which uses explosives or transponders to send sound waves through various layers of bedrock to discover its structure as the sound is reflected back to an array of sensors.
The problem is that methods like these are highly disruptive to marine life and the resolution of such imaging is extremely poor. Acoustic Zoom works on a different principle than conventional seismic imaging. Instead of reflecting sound energy back from the depths of the sea, Acoustic Zoom measures how energy is scattered as a beam of sound scans through an area before being picked up by a 16-spoke sensing array set on the ocean floor. The signal is then digitally processed and a much higher resolution image is built up.
As the system involves more sensors and transmitters, each pulse of sound can be lower energy. The array means scanning can be done in a less impactful but more efficient way. Moreover, the new images reveal details, such as fractures and fissures in strata, which were previously invisible with conventional seismic imaging.
The sound used by Acoustic Zoom is created by a form of “marine trombone” that operates at a much higher frequency, over a longer time, and at lower energies than conventional sonar methods. This lower energy and higher frequency reduces the impact on marine life. It allows researchers to gain a detailed understanding of geological features without drilling, and removes the need to use explosives to create sound waves for seismic images.
http://www.sciencedirect.com/science/article/pii/S1875510014002728 (Published Paper)