Home
Profile
Nautical Vessels
Core Sampling
Geophysics
Our staff
Primary Projects
Informations
Contacts
Links






Home » Geophysics
Geophysics
 
Preparatory activities for core sampling consist of a series of surveys to explore morpho-bathymetric and stratigraphic characteristics of the sea bottom, as well as the search and identification of possible explosive devices in the areas of involvement.

The activities conducted in this area are divided into:

BATHYMETRIC SURVEYS.


For precise bathymetric findings, GeoPolaris uses multibeam high-resolution sonar with probes to measure of the speed of sound in the water: the multibeam system simultaneously measures the sea bottom at a large number of points, mapping a broad tract of the sea bed. The accuracy of measurement is better than 1% of the depth of the water.
The system for navigation and the acquisition and processing of data allow real time qualitative control and later creation in the processing phase. The positioning system, including a gyrocompass and a motor sensor, allows correct geographic referencing of the data acquired.
GeoPolaris uses models such as the RESON SeaBat 8125 or the SEA SWATH Plus.

Three-dimensional images of a former pier, obtained from multibeam Reson SeaBat8125, integrated with positioning system GPS-RTK Leica SR 530 and fibre-optic motor sensor/gyrocompass Ixsea OCTANS 3000

Three-dimensional images of a jetty, obtained from multibeam R2 Sonic 2024, integrated with positioning system GPS-RTK Leica 1200 and fibre-optic motor sensor/gyrocompass Ixsea OCTANS 3000

Up

GEOMORPHOLOGICAL SURVEYS


The side scan sonar is the most suitable instrument to obtain the morphological characteristic of the sea bottom: for precise morphological findings, GeoPolaris uses high-resolution digital side scan sonar.
The side scan sonar provides a highly-detailed “acoustic image” of the sea bottom: the system is comprised of two transducers mounted laterally on an instrument pulled into the sea, served by a pulley and a signal wire: the nearness of the instrument to the sea bottom is reflected in its high stability and a reduced level of environmental noise.
The instrument is connected with a computer on which software is installed for acquisition and digital processing of the data. In the recovery phase, the software allows creation of a complete mosaic of the area surveyed.
To obtain a high degree of precision in positioning, the acquisition software is interfaced with the navigation system.
GeoPolaris uses models such as the KLEIN3000, the BENTHOS SIS1500 or the Edgetech 272 td.

Mosaic image of a former pier obtained from the data of the Edgetech 272 td side scan sonar, integrated with positioning system GPS-RTK Leica SR 530.

Up

SEISMO-STRATIGRAPHIC SURVEYS
The acoustic profile of the sea bottom allows exploration of stratifications of deep sediment, essential for the purposes of determining characteristics of the areas of the geological and geotechnical survey: the seismo-stratigraphic findings produce a continual description of the substrata of the sea bottom, allowing extension of the results of a localized geological sample to broader areas.
For precision seismo-stratigraphic findings, GeoPolaris uses a high-resolution Sub Bottom Profiler: the system allows stratigraphic surveys with penetration into sediments up to 40 metres (on clay or silt sea bottom) with accuracy on the order of centimetres.

The new generation of Sub Bottom Profiler with CHIRP or PARAMETRIC technology guarantees high resolution, using digital analysis and the improvement of the signal/sound relationship with specific digital filters. The instrument is connected to a computer on which the software is installed for the acquisition and digital processing of the data. To obtain a high degree of precision in positioning, the acquisition software is interfaced with the navigation system.
GeoPolaris uses models such as the
Innomar SES 2000 (10Mb PDF file) or the BENTHOS CHIRP II.

Image of the layers of sea bottom obtained from the data sub bottom profiler
Benthos CHIRP II: 1) sea bottom; 2) multiple reflections.

Up

MAGNETOMETRIC SURVEYS

The magnetometric survey allows discovery of the presence of iron masses as well as the search and identification of possible explosive devices in the areas of involvement.

The system is comprised of an on-board unit interfaced with the positioning system, used for the acquisition and the recording of the data, and a marine sensor that displays the data. The instrument continuously measures the intensity of the magnetic field, composed by the sum of the magnetic ground field and local anomalies. This latter, based on its form, can be connected to the presence of a magnetic body lying on the sea bottom or buried at variable depths.

GeoPolaris uses the Cesio Geometrics G882 magnetometer or the SeaSPY magnetometer with Overhauser effect.

Three-dimensional representation of the magnetic field within a former pier, obtained with the Cesio Geometrics G882 magnetometer: the “depressions” represent magnetic anomalies due to the presence of metallic masses.

Up

 
 
 


Copyright © 2004/2010 GeoPolaris s.r.l.