[S-EM15] Electric, magnetic and electromagnetic survey technologies and scientific achievements

[SEM15-11] Investigating Mid-Mantle Electrical Conductivity Beneath Taiwan Derived from C-response Function.

*Ding-Jiun Lin^1,2, Kiyoshi Baba¹, Ping-Yu Chang^1,2,3 (1.Earthquake Research Institute, The University of Tokyo, 2.Department of Earth Sciences, National Central University, Taiwan, 3.Earthquake Disaster & Risk Evaluation and Management Center, Taiwan)

Keywords:C-response, electrical conductivity, geomagnetic depth sounding, mantle

The electrical conductivity structure of the mid-mantle (300–900 km depth) beneath Taiwan was investigated for the first time using geomagnetic depth sounding (GDS). This study analyzed geomagnetic field data from seven observatories in Taiwan and three international observatories. GDS responses at each observatory were estimated over periods ranging from 1.3 to 42.7 days. Since the ocean effect significantly distorts the responses due to the stark contrast in electrical conductivity between highly resistive continental crust and highly conductive seawater and oceanic sediments, a three-dimensional conductivity model was applied to correct for these distortions. After applying the ocean-effect corrections, the responses were inverted to derive one-dimensional electrical conductivity-depth profiles for each site. The results indicate regional variations in conductivity, with the mid-mantle beneath eastern Taiwan appearing more conductive than that beneath northern Taiwan. Conductivity values range from 0.01 to 1.5 S/m in the north and 0.04 to 3.5 S/m in the east.