The Mohr circle, most commonly met in the analysis of mechanical stress, is used to depict magnetotelluric impedance information, taking the real and quadrature parts of magnetotelluric tensors separately. The magnetotelluric concepts of two-dimensionality, three-dimensionality, skew and anisotropy are then all given quantitative expression on a diagram, as are various magnetotelluric invariant...

The results of application of multichannel Kalman filtering to reduction of uncorrelated noise in magnetotelluric recordings are discussed in this article. Magnetotelluric method of Earth structure recognition is shortly presented together with the its most popular measurement method called the remote reference method. The basic theory of nonstationar, discrete Kalman filter and its implementat...

The magnetotelluric method has improved significantly in recent years and is being used in hydrocarbon exploration in regions where seismic exploration is difficult. This includes areas where highvelocity carbonates and volcanic rocks are present in the near surface, overthrust belts, and in subsalt imaging. Magnetotelluric exploration was used in the Rocky Mountain Foothills in 2002 to determi...

The usual methodology used in magnetotelluric signal processing (MT) has been studied and applied to the case of audio-magnetotellourics (AMT). The results obtained have proved not to be good enough in order to obtain a good subsurface resistivity model. Therefore, some changes have been made to the methodology of signal processing so that it suits audio-magnetotellurics. These changes have app...

The method of Hybrid Adaptive Filtering (HAF) aims to recover the recorded electric field signals from anomalies of magnetotelluric origin induced mainly by magnetic storms. An adaptive filter incorporating neuro-fuzzy technology has been developed to remove any significant distortions from the equivalent magnetic field signal, as retrieved from the original electric field signal by reversing t...

S U M M A R Y Robust magnetotelluric response function estimators are now in standard use in electromagnetic induction research. Properly devised and applied, these have the ability to reduce the influence of unusual data (outliers) in the response (electric field) variables, but are often not sensitive to exceptional predictor (magnetic field) data, which are termed leverage points. A bounded ...

Conductivity models beneath the Nanga Parbat Haramosh Massif (NPHM) derived from magnetotelluric soundings reveal that there is no widespread, interconnected, conductive aqueous fluid to minimum depths of 40 km below sea level. Given the continuing tectonic denudation, young granitic and migmatitic bodies indicating partial melt at shallow crustal depths, and active seismicity, this result is s...

The telluric sounding (TS) method is introduced as a potential tool for monitoring hydraulic fracturing at depth. The advantage of this technique is that it requires only the measurement of electric fields, which are cheap and easy when compared with magnetotelluric measurements. Additionally, the transfer function between electric fields from two locations is essentially the identity matrix fo...