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Magnetometer/Gradiometer Surveys

Marine magnetometers are used to identify objects containing ferrous metals resting on or buried just below the surface of the seafloor. During a survey, the magnetometer records the total earth’s magnetic field along a trackline.  The data are analyzed to identify anomalies (deviations from the background field) that are caused by ferrous objects.

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Anomalies associated with such objects can be distinguished from other sources of magnetic disturbances which produce longer duration disturbances, such as local geological structures.  Although an individual anomaly represents only the location along a trackline in which the disturbance was measured, by comparing data along adjacent tracklines and correlating with other geophysical results (i.e. side scan sonar imagery, high-resolution subbottom profiles of the very shallow subsurface) it is possible to calculate estimates of the location of the ferrous object and provide more insight about the nature of the object.

Representative Projects

Coastal Monitoring Fig. 2

Coastal Monitoring: Offshore Bethany Beach, Delaware

In 1988 several pieces of artillery shells were discovered on Bethany Beach and Sea Colony Beach in Delaware. A recent beach replenishment project used sand recovered from a borrow area within the bounds of a historic anti-aircraft target range operated ...
Submarine Cable Fig. 2

Submarine Cable and Pipeline Routing: Massachusetts Bay

Ocean Surveys, Inc. initially performed a desktop study to compile geologic, oceanographic, sediment chemistry, and marine activity background information supporting the feasibility assessment of the project. This research was followed by a reconnaissance level marine geophysical survey along an alignment ...

Wind Farm Development: Atlantic Ocean, Offshore Rhode Island

From 2009 to 2017, OSI provided extensive survey and data analysis for the wind farm development offshore Rhode Island. These services were performed in support of all phases of the design, permitting, and construction of five wind turbines, inter-array, and ...