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A Study on the Luminous Phenomena Accompanied with Earthquake (Part 1)
Luminous phenomena accompanied with earthquakes occurred often at Matsushiro during 1965-1967. The author collected thirty-four examples and after several researches some of them might be unrelated phenomena, such as sheet lightning, meteor, twilight and zodiacal light, which are misconceived to be related. Excepting these cases, at least eighteen examples are considered to have real connection to earthquakes. He could not feel that the event of luminescence over a mountain area for several ten seconds in a clear and calm winter night was one of the physically known phenomena.
Generally the luminescences are as follows:
(i) The central luminous body is a semi-sphere with a diameter from several ten to several hundred meters contacting with the earth surface. The body is white. The reflection on a cloud in the vicinity is coloured, however.
(ii) The luminescence follows an earthquake. But its duration is several ten seconds.
(iii) Places in which the luminescence occur are restricted in the several areas, which are not the epicenter of the related earthquake. Those places are mountain summit composed of quartz-diorite with fault.
(iv) Spherics follows the luminescence generally. And it occurs frequently at the time of the pass of a cold-front.
(v) Magnetometer show no variation at the time of luminous phenomena. T. Terada described thirty-five years ago that the phenomena might occur in the stratosphere, but the reports from Matsushiro show that the phenomena occurred on low atmosphere contacting with the earth and together with some increase of air-eartn current. The author thinks that the luminescence is essentially au atmospheric electrical phenomenon, however the mechanism of the trigger action given by an earthquake is unknown at present time.
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