A magnetotelluric profile across Central Java']Java, Indonesia

Along a N30 degrees E striking profile in central Java, Indonesia we recorded broadband magnetotelluric data at 8 sites in the period range 0.01s - 10000s. A preliminary analysis of apparent resistivity, phase and magnetic transfer function data favours a one-dimensional interpretation of most sites for the upper 3-5 km of the crust and a two- or three- dimensional structure for the lower crust. Several conductive features can be distinguished: (i) a strong "ocean effect" at the southern most site, (ii) a zone of very high conductivity in the central part df the profile, and (iii) a conductor in the north that cannot be caused by the shallow Java sea. We discuss tentatively causes for these anomalies. The conductor in the central part of the profile is probably connected with volcanic or geothermal activity, while the anomaly in the north could be an expression of processes associated with an active fault zone.