Marine Services :: Marine Geophysical Investigations
Marine geophysical investigations use a wide range of sensors to remotely characterize the seafloor, lakebed, or river bottom, in addition to features on or below these surfaces. Assessing underwater geology and structures can provide a direct cost benefit to clients by providing situational context through a comprehensive depiction of a project site.
As part of our geophysical services, DEA provides sub-bottom profiling, seismic profiling, side scan sonar imaging, ground-penetrating radar, underwater acoustic scanning and imaging, marine magnetometer surveying, and tone-induction tracking of pipelines and cables. Our instruments can be deployed from a wide range of customized DEA-owned survey vessels, or vessels of opportunity.
Sub-bottom profiling surveys map underwater subsurface geology using a variety of acoustic sources. DEA has used frequencies as high as 24 kHz to precisely characterize finely layered materials, and frequencies as low as 500 Hz to obtain more than 200 feet of penetration through thick river sands.
Side scan sonar imaging surveys map underwater features, providing an acoustically generated image that can be used to characterize seafloor or riverbed features, identify obstructions projecting above the bottom that may impede or threaten navigation or construction, delineate bottom materials, or aid in search and recovery missions.
Magnetometer surveys measure the ambient magnetic field and can locate concentrated masses of ferrous material. These surveys are often used to locate ship anchors or buried pipelines, or to investigate proposed cable and pipeline routes for the presence of cultural features.
Integrated systems allow for efficient data collection by incorporating high-resolution side scan sonar, sub-bottom profiler, and marine magnetometer deployed from a single, 2,000-meter-rated towbody. DEA utilizes an Applied Acoustics Nexus II USBL (ultra-short base line) acoustic tracking system to provide accurate towfish location during deep-water operations.