tMag - A New Towed Gradient Magnetometer Array for Near Surface Geophysicst

We have developed a new towed magnetic gradiometer array for environmental, engineering, and archaeological applications. With 16 sets of vector magnetometers plus accelerometers on a low-noise platform we can construct an estimate of the full magnetic gradient tensor. A high sample rate and suspension system allows for rapid collection of data—up to 70 hectares a day at full sensor coverage, while careful design of the platform has removed the majority of noise sources from proximity to the sensors. The application of vector magnetic gradiometry allows for advanced processing techniques such as calculation of tensor invariants, principal component analyses, wavelet decomposition, and more. In this abstract, we describe the design of the gradient array and introduce an initial processing workflow. We also discuss system noise characteristics and show an example from a clay tile drain mapping application demonstrating the efficacy of the system for accurate detection of low-signal sources.