Submarine cable route investigation
Main purpose of the submarine cable route survey is to select the most suitable cable laying route. This survey starts from the collection of data on natural condition and human work condition to select the survey route. Field work is consisting of the land site survey, inshore survey by small boat and offshore survey by large vessel, and the survey flows as the data acquisition of geophysical survey and magnetic survey, data analysis, selection of field recommended route, sampling and other necessary survey.
DTS (desk Top Study)
DTS is the study to select the suitable survey route and to obtain the necessary data for cable construction. Collection data consist of natural condition such as bathy, geology, oceanography and meteorology, and human work condition such as fishing activity, shipping activity, military activity, existing cables, etc. These data are analyzed to select the survey route, and the field survey starts.
Land Site Survey
Landing point and others are determined by S-GPS or VRS-GPS, and the topography around landing site is measured by K-GPS, total station, level, etc.
Topography at coastal area is measured by diver cross section leveling. Diver survey along the route is carried out for the photography of video and camera, clarification of seabed material and sediment thickness and existing cable search by magnetometer.
Generally, the inshore survey by small boat and the offshore survey by large vessel are carried out in parallel. The survey contents are as follows:
- Bathymetric survey by multi-beam echo sounder
- Seabed feature survey (Side scanning) by side scan sonar
- Geological survey by sub-bottom profiler
- Seabed sampling by gravity corer and grab sampler
Others such as current survey and magnetic survey are performed as necessary.
Acquisition data are analyzed on board day by day to supply the chart such as bathymetric chart, seabed feature chart and geological chart for the selection of most suitable route and daily meeting.