A Two-Dimensional Conductivity Model across Central Japan

摘要: Horizontal profiles of geomagnetic transfer function were obtained at the periods 15, 30, 60 and 120 minutes by analysing 3-component variation data 21 sites in central part Japan 7 on Philippine Sea floor. A two-dimensional conductivity model was constructed, use finite element method, to represent spatial period dependence these functions.Characteristics observed functions Pacific coast continental shelf well explained introducing a highly conductive layer beneath plate depth about 30km addition large contrast between land seawater. In order account for anomalous phase northern half sites, lower crust required this region. This crustal conductor also reduction effect sea coast, existence free water considered as its likely cause. Our result did not require upper mantle Sea, least 200km away from explain data, which may suggest that motion is possible cause asthenosphere partial melting.