Multi-station superposition for magnetotelluric signal

Extending the observation time to increase the length of time series is the most effective but consuming way to improve the signal-to-noise ratio of magnetotelluric (MT) signal. Multi-station superposition technique at present proposed for magnetotelluric survey aims to attenuate random noises by multi-station synchronously observation at one site. The idea stems from seismic array stacking and is mathematically verified corresponding to a linear random noise model. The multi-station superposition can be done in time and frequency domains. A practical testing measurement was performed by setting three stations on vertexes of an equilateral triangle and a single station on centre of the triangle in desert area of the Tarim basin, western China. The results of the testing data demonstrate the effectiveness of the proposed scheme. The method has great potentials for long-period MT survey in dramatically reducing the observation time and suppressing the static shift caused by near-surface inhomogeneities.