Geophysical Survey

Side scan sonar


A side scan sonar build a graphical image of the sea floor, similarly to an aerial onshore photography.


A fish, transmitting and receiving a high frequency acoustic signal, towed behind a boat is combined with a recording device. This towed fish insonify the sea bed perpendicularly to the vessel route. The swath width of the surveyed sea floor depends on the chosen scale.

Implementation and data processing

The Side Scan Sonar fish is towed behind a vessel in order to cover the whole survey area.
An accurate vessel and fish positioning system is imperatively required (e.g. a DGPS and USBL).

Side scan sonar images are recorded, corrected from obliquity and merged to build a mosaic.
Interpretation of the data allows to draw a sea bed cartography.


Sea bed physiographic charting.
Géomorphological and sedimentological analysis of the site.
Sea grass charting.
Existing structures and obstructions location.