Electromagnetic Radiation Phenomena before and after the 1995 Hyogo-ken Nanbu Earthquake.

Abstract

Before and after the 1995 Hyogo-ken Nanbu earthquake on January 17, three kinds of phenomena of electromagnetic radiations were recorded at Uji Station, Kyoto Prefecture, Japan. They were: 1) A series of increases in number of electromagnetic noises starting from 12 days before the main shock to 2 days after the main shock, 2) A clear increase of electromagnetic noises from 5 o'clock on January 17, and 3) A co-seismic change of electric field intensity in the VLF range observed at the time of arrival of seismic waves with large amplitude, then the area around Uji Station was strongly shaken. An investigation by questionnaire about the anomalous electromagnetic phenomena before and after the earthquake was also executed after the earthquake by mailing to amateur radio operators around the focal region, i.e. those in Takarazuka, Itami and Sumoto Cities. The daily variations of the numbers of anomalous electromagnetic phenomena reached a peak just before and just after the earthquake.