Artículos de revistas
A discussion of bias in magnetotelluric responses
Fecha
2009-07Registro en:
Pomposiello, Maria Cristina; Booker, John; Favetto, Alicia Beatriz; A discussion of bias in magnetotelluric responses; Society of Exploration Geophysicists; Geophysics; 74; 4; 7-2009; 59-65
0016-8033
1942-2156
CONICET Digital
CONICET
Autor
Pomposiello, Maria Cristina
Booker, John
Favetto, Alicia Beatriz
Resumen
Magnetic-field noise biases magnitudes of magnetotelluric response functions such as resistivity, impedance, and the induction vector (tipper). This is particularly severe in the so-called dead band between about 1- and 10-s periods. The standard approach to remove these biases is to use a magnetic remote reference. In cases where this is unavailable or does not work because noise is correlated at the local and remote sites, it is possible to extract unbiased estimates using an inversion algorithm that predicts the magnitude from the phase. However, an important condition for this to be successful is that phase estimates are unbiased. Phase can be biased if parallel components of the electric and magnetic fields are correlated. This arises when the structure is 3D or when a 2D response is estimated in coordinates not parallel to strike. Improvements in electric field measurements make electric field references a viable option for estimating low-bias responses up to periods approaching 1000 s.