Sub-bottom profiling or imaging is an acoustic method used to image beneath a water body. This method relies on a technique that is similar to simple echosounders. A sound source emits a signal vertically downwards into the water and a receiver measures the return signal that has been reflected from the floor of the water body. Some of the acoustic signal will penetrate the sediment-water interface and be reflected when it encounters a boundary between two layers having different acoustical properties. The system uses this reflected energy to provide information on features beneath the sediment-water interface.
Sub-bottom profiling systems can be useful for characterizing subsurface structure without the need for more intrusive methods such as sediment cores and drilling.
Sub-bottom profiling collects high resolution, continuous reflection soundings. Through the use of different acoustical sources, different features can be explored. Low frequency boomers are used for deep penetration of lithologic units. High frequency pingers are for high resolution shallow surveys. The sub-bottom profiling method can be applied to almost any type of water body and, salt water environments, rivers, and lakes, have been successfully investigated with this technology. The depth of penetration can be as deep as 90 feet, but is dependant on the physical properties of the bottom materials.