Kongsberg Maritime EA440 Sub-bottom Profiling

Kongsberg EA440 for sub-bottom profiling

Sub-bottom profiling is used to image the sediment layers below the sea bottom.

The EA sub-bottom is an inexpensive and portable solution well suited for imaging the top layers, e.g. for port or river surveys.

Low-frequency sound signals will penetrate the seabed and provide reflections from layers below the seabed. For EA440 a 15 kHz transducer is normally used, although for EA440 limited to a max of 300m water depths.

The signals penetration, and thus how deep into the seabed that sediment layers can be seen, is limited by source level and beamwidth. For EA440 max penetration of around 10-15m is expected, which makes this solution a well-suited solution for port surveys, river surveys, and for applications where only the top-level sediments are of interest.

Different bottom conditions (rock, sand, mud, etc.) will result in different bottom echoes in the EA440 echograms. The EA440 software allows for adjusting the bottom gain, and the presentation is changed depending on the bottom type. The sub-bottom data will be saved in the raw data files for further adjustments. The EA440 software also provides SEGY output of the raw data, which is the standardized exchange format for sub-bottom data that can be used by geologists for further interpretation and mapping of the sub-bottom conditions.