C-responses estimation of geomagnetic depth sounding using regularization method and its application in Northeast China

Abstract

In this paper, we introduce a technique to obtain smoother C-responses in geomagnetic depth sounding. Instead of frequency by frequency, C-responses in entire frequency range are estimated simultaneously. In order to do so, after obtaining the spectrum of Hy and Hz, the equations relating C-response with Hy and Hz are combined for a batch frequency to form a linear equation set, from which, incorporating the requirement of smooth constraint on C-responses, we could define a regularized least-squared inversion problem. And to minimize influence of noise, data squared coherencies between Z and H signals are used to weight prediction error in order to suppress unreliable data. Synthetic data tests indicate that using the optimal regularization parameter determined by V-curve method other than L-curve method, regularization method could produce rather smooth C-responses from noise interfered signals. C-responses in Northeast China are thus obtained and then 1-D inversion is applied, from the obtained electrical and combining the Global and regional tomographic results, it is speculated that the stagnant plate in MTZ leads the high conductivity anomaly in Northeast China.