
TY  - JOUR
A1  - Sedaghat, Bibirabea 
A1  - Schaa, Ralf 
A1  - Harris, Brett 
A1  - Pethick, Andrew 
A1  - Costall, Alex 
A1  - Duan, Jingming 
A1  - Jiang, Wenping 
T1  - Magnetotelluric, Basin Structure and Hydrodynamics; South West of Western Australia
JF  - ASEG Extended Abstracts
JO  - ASEG Extended Abstracts
Y1  - 2018
VL  - 2018
IS  - 1
SP  - 1
EP  - 5
KW  - 
UR  - https://doi.org/10.1071/ASEG2018ABP095 
N2  - A prominent TE and TM mode split is observed in magnetotelluric (MT) data below 0.5 Hz collected in the Perth Basin over the Harvey Ridge, Western Australia. We investigate the causes of mode splitting and consider implications on inversion of the MT data to subsurface electrical conductivity distribution. Twenty-five broad-band MT stations were acquired and remote reference processing was completed to arrive at a data set located midway between the Darling Fault and the Indian Ocean. We used forward modelling to test our strong suspicion that the Indian Ocean, Darling fault and architecture of the Granitic Basement were indeed the major contributors to mode splitting that we observed. Forward modelling of synthetic data was completed for comparison with the Harvey MT data. We were surprised at the match between synthetic and field data given the simplicity of the forward model and the considerable lateral distance between the MT soundings and the Indian Ocean or Darling fault. We were then able to make significant improvements to the MT inversion outcome by introducing a large scale geo-electrical architecture as the seed model for inversion. Our work demonstrates that large scale geo-electrical contrasts at considerable lateral distance from an MT transect, or the target zone need to be systematically introduced to the inversion if a quality outcome is to be achieved. 
ER  -

