抄録
Aeromagnetic surveys were carried out over the Izu-Oshima Volcano, before and after the November 1986 eruption. The comparison between the pre- and post-eruption aeromagnetic data showed no significant change in the magnetic anomaly. The magnetic subsurface structure of the Izu-Oshima Volcano was investigated on the assumption that the volcano is magnetized in the present Earth’s field direction. The topography magnetization was determined from correlation between the original aeromagnetic data and the magnetic anomaly produced by uniformly magnetized terrain. The estimated topography magnetization was 7.0 A/m. The analysis for the regional trend in the residual magnetic anomaly after the terrain correction represented the existence of a large-scale dike in the NW-SE direction. The local anomalies in the residual map after the removals of terrain and dike effects correspond to the distribution of craters and lavas of the Izu-Oshima Volcano.
