Geometrics' Article on Magnetometer Arrays Featured in May Issue of Ocean News & Technology

Jul 03, 2014 | Posted in Blog, News

Multiple Magnetometer Sensor Arrays And Their Applications In Marine Environmental Surveys

A magnetometer is a device used to measure the magnetic field at a point in space. All magnetometers can be divided into two groups — vector magnetometers measure the magnetic field in terms of its components (fluxgate and SQUIDs are examples) while total field magnetometers such as Proton Precession, Overhauser and Optically Pumped Quantum magnetometers measure the scalar (directionless) value of the field. The total field magnetometers measure the amplitude of the magnetic field regardless of the magnetometer orientation. All magnetometers are passive devices that do not rely on energizing the nearby environment.

Manmade objects made of steel or iron alloys such as a ship’s hull, munitions and pipelines can distort the Earth’s field and are therefore detectable by sensitive magnetometers.

Marine Portable Magnetometers

Marine magnetometers are produced commercially by two companies, Marine Magnetics of Markham, Ontario, Canada and Geometrics of San Jose, Califonia, USA. The Marine Magnetics technology is based on a proton precession variant known as Overhauser, which has low power requirements, good absolute accuracy and a sample speed of 1 to 5 Hz. Geometrics produces an optically pumped Cesium Vapor magnetometer that has high sensitivity and high sample speed of 10 to 20 Hz. Marine magnetometers have digital RS-232 data output and provide other measurements such as depth and height above the seafloor.

Locating Unexploded Ordinance (UXO) and chemical munitions

Magnetometers are routinely used for UXO clearance surveying because explosive projectiles include a steel shell. One of the highest concentrations of UXO is in the coastal waters off the southern UK and Northwestern Europe. Here, WWII bombardment and post-conflict dumping of munitions left large areas of the seabed littered with hazardous material. The munitions include conventional explosives as well as chemical warfare agents...


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