Surface-NMR in Urban Area - A No Go?

Surface-Nuclear-Magnetic-Resonance (surface-NMR) has shown a continuous development towards a frequently used and established hydro-geophysical tool during the last decades. However, the measured signals are as low as few tens of nanovolts and therefore often contaminated by significant amounts of electromagnetic noise. Consequently, surface-NMR has been used on remote area with great success but is also known to be a technique that needs to be chosen with respect to low noise conditions. Several developments both on instrumentation and processing allow overcoming these strong restrictions on applying surface-NMR. Multi-channel devices use remote references to cancel harmonic noise. High sampling rates of the used analog-to-digital converter allow for advanced de-spiking schemes. Finally, the combination of formerly known figure-of-eight loop layouts with remote references provides access to areas close or even within the borders of settlements. We give several examples demonstrating these developments and highlighting the new capabilities of the technique.