Earth Planets Space, Vol. 51 (No. 10), pp. 1145-1151, 1999
Geological Survey of Japan, 1-1-3 Higashi, Tsukuba, Ibaraki 305-8567, Japan
(Received November 7, 1998; Revised May 11, 1999; Accepted May 11, 1999)
Abstract: A two-dimensional inversion method was applied to the COPROD-2S2 dataset, which consists of apparent resistivity, phase, and magnetic transfer functions at 33 sites over 3.5 decade period band. The modeling procedure adjusts tradeoff between the data misfit, model roughness and static shift L2 norm. Two different models were made using strong and weak constrains on the shallower structure than the typical shortest skin depth (1.5 km). Stronger constraint on the shallow horizontal roughness lead to larger static shifts in TM mode and horizontally smoother structure. This shows tradeoff between the shallow resistivity roughness and static shift in TM mode. However, both models had consistent features in the deep resistivity structure and the static shift in TE mode. Both models showed consistent results on the background structures, which were estimated by the resistivity blocks outside the data area.