title: Subterranean electrical structure of Kozu-shima volcanic island, Japan.
abstract: Following the electric current injection experiment carried out in 2009, a VLF-MT (Very Low Frequency Magnetotelluric) survey has been conducted in Kozu-shima Island to obtain further information on the subterranean electrical structure that might help understanding the results of our monitoring of geoelectric potentials. A number of VAN-type pre-seismic geoelectric potential anomalies were observed in 1997-2000, even showing a remarkable "Selectivity". However, similar pre-seismic anomalies were not observed during the Izu-Island volcano-seismic swarm 2000. All these observations would require extremely high degree of heterogeneity in the subterranean electrical structure of the volcanic island and its possible time changes. Several correlations between the results of this survey and the volcanic geology of the island and ground water distribution were found. Further investigation is needed for a complete explanation of the observed phenomena.
authors.affiliation: Earthquake Prediction Research Center, Tokai University, Shizuoka, Japan.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Orihara
authors.forename: Masashi
authors.initials: M
authors.lastname: Kamogawa
authors.forename: Akihiro
authors.initials: A
authors.lastname: Takeuchi
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Fukase
authors.forename: Toshiyasu
authors.initials: T
authors.lastname: Nagao
mesh_terms: D017097:Electric Impedance; D004560:Electricity; D005843:Geography; D007564:Japan; D018707:Volcanic Eruptions / Q000032:analysis*