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A new-type source of power line harmonic radiation (PLHR) is described in this paper to point out its significance to the magnetospheric emissions. Characteristic electromagnetic fields were observed over the Kola Peninsula, northern Russia, during the flight of the balloon B15-2N in 1982. The source is characterized by (a) the fundamental frequency of 24.4 Hz, (b) the harmonic spectrum continuously extending up to VLF, and (c) the isolation from commercial power lines. These characteristics are different from the previously reported PLHR sources that could trigger the magnetospheric emissions. Based on the low impedance field and the amplitude variation along the balloon trajectory, the source can be modeled by a horizontal electric dipole or a horizontal magnetic dipole, and then the source distance is estimated within the induction area of a few hundred kilometers. The most probable source is an electric railroad or a single-phase power line, driven by an isolated power generator, and located on the Kola Peninsula. Estimating the radiation power through the ionosphere, it is shown that enough power to trigger magnetospheric emissions may be radiated into the magnetosphere from the source. Therefore, it is suggested that the source can be recognized as a new-type PLHR source possibly related to magnetospheric emissions.

At the time of the major volcanic eruptions on November 15 and 21, 1986 at Mt. Mihara, Izu-Ohshima Island, Tokyo territory, Japan, a detector from a multipoint direction-finding network to detect electromagnetic emissions was operating. Since October 20, 1986 impulsive noises at 82kHz were recorded, and these anomalous burst-like noise observations increased after November 3. At 10-16 JST (Japanese Standard Time, UT+9 hours) on November 14, several strong noise bursts were observed, and the first major eruption occurred at the main summit crater of this volcano at 16 JST on November 15. At 10-12 JST on November 21, noise bursts were observed and four hours later, 19 new craters erupted suddenly on the side slope of the mountain, both in and outside the caldera, simultaneously with the intrusion of dykes in the mountain body. These records are the first observations of electromagnetic emissions as precursors to volcanic eruptions ever recorded. The authors present this paper in the form of a short note for data presentation, because analysis of these data and comparison with other observations is still continuing.