title: Electric and magnetic phenomena observed before the volcano-seismic activity in 2000 in the Izu Island Region, Japan.
abstract: Significant anomalous changes in the ultra low frequency range (approximately 0.01 Hz) were observed in both geoelectric and geomagnetic fields before the major volcano-seismic activity in the Izu Island region, Japan. The spectral intensity of the geoelectric potential difference between some electrodes on Niijima Island and the third principal component of geomagnetic field variations at an array network in Izu Peninsula started to increase from a few months before the onset of the volcano-seismic activity, culminating immediately before nearby magnitude 6 class earthquakes. Appearance of similar changes in two different measurements conducted at two far apart sites seems to provide information supporting the reality of preseismic electromagnetic signals.
authors.affiliation: Riken International Frontier Research Group on Earthquakes, Earthquake Prediction Research Center, Tokai University, 3-20-1, Orido, Shimizu 424-8610, Japan. suyeda@st.rim.or.jp
authors.forename: S
authors.initials: S
authors.lastname: Uyeda
authors.forename: M
authors.initials: M
authors.lastname: Hayakawa
authors.forename: T
authors.initials: T
authors.lastname: Nagao
authors.forename: O
authors.initials: O
authors.lastname: Molchanov
authors.forename: K
authors.initials: K
authors.lastname: Hattori
authors.forename: Y
authors.initials: Y
authors.lastname: Orihara
authors.forename: K
authors.initials: K
authors.lastname: Gotoh
authors.forename: Y
authors.initials: Y
authors.lastname: Akinaga
authors.forename: H
authors.initials: H
authors.lastname: Tanaka
mesh_terms: D004560:Electricity; D004574:Electromagnetic Fields; D007564:Japan; D008280:Magnetics; D013997:Time Factors; D018707:Volcanic Eruptions