PHS undertook a magnetometer survey to detect significant ferrous objects in a specified area, which may have potentially posed a hazard to dredge drag head operations.

The purpose of this type of survey is to highlight areas of caution for the upcoming capital dredging campaign. Where there are materials or objects that have a high magnetic permeability (such as objects that contain iron, nickel, or cobalt) the earth’s magnetic field distorts around the object by ‘amplifying’ or decreasing the earths ambient magnetic field. These distortions in the magnetic field or ‘magnetic anomalies’ generally result in smoothly varying and asymmetrical gradients such as the below examples shown. 

The first image is an example Magnetic Anomaly Reading, and the second image is a data sample demonstrating effect of passing Iron Ore Ship.