Comparison of the impedance estimation methods by using long period magnetotelluric data measured in northwest anatolia

Magnetotelluric (MT) method is one of the main geophysical methods used to investigate the deep resistivity structure of the earth. Nowadays, with the new data acquisition systems developed in the MT method, the time-dependent changes of the electric and magnetic field can be measured in the period range of 0.0001 - 10.000 seconds covering audio, broadband and long period ranges. During MT data collection, the data can be transferred to the office in real time for data analysis. In the first stage of MT data interpretation; impedance estimation is performed in frequency domain by performing fast Fourier transform of the measured electric and magnetic fields in time domain. Errors in impedance estimation will cause large noise in the inversion of MT data and will result in models that do not represent the subsurface. The aim of this thesis is to compare the existing impedance estimation methods and the methods used in impedance estimation from MT data measured in the period range "0.0001 - 10.000 seconds" and to compare the advantages and disadvantages of these methods compared to each other. As a result of this thesis, it is proved that the pre-processing filters used in the data processing and manual elimination are very important for the generation of a quality MT time series dataset.