13 April, 2010 (11:15 GMT), 5 Merrion Square, Dublin 2.

Speaker: Maxim Smirnov, University of Oulu, Finland.
Title: Magnetotelluric array data processing. EMMA project.

Abstract:

In magnetotelluric (MT) method reliable estimation of transfer functions is an important step towards the final interpretational model. Several important aspects of magnetotelluric data processing are considered. Application of robust estimators proved to be very efficient in improving the accuracy of MT transfer functions estimations. Multivariate analysis (Egbert 1987) opens another perspective to further facilitate data processing. It allows to fully explore the simultaneous nature of magnetotelluric array observations and provides some hints on source field structure, as well as noise behavior. Two electromagnetic arrays were measured in EMMA project to study conductivity structure of the Archaean lithosphere in the Fennoscandian Shield. The first array was operated during almost one year, while the second one was running only during the summer time. Twelve 5-components magnetotelluric instruments with fluxgate magnetometers recorded simultaneously time variations of Earth’s natural electromagnetic field at the sites separated by c. 30 km. The quality and duration of the first EMMA array provides an excellent possibility to test different approaches to data analysis. The results of EMMA array data processing are presented.