ON THE DILATANCY-MAGNETIC EFFECT
QI GUI-ZHONG(Institute of Geophysics, Academia Sinica)
Piezo-magnetic effect of rock medium is here considered as not the only physical cause of the variation of the geomagnetic field in connection with the occurrence of earthquakes. In this paper, it is believed that from the facts observed in the Xingtai (邢台) Earthquake region in China, the local magnetic variations supposed to be associated with some of the earthquakes can hardly be interpretated by the Piezo-maguetic idea. Therefore, a new idea which is termed as the "Dilatancy-magnetic Effect" has been proposed. It is suggested that due to micro-fracture and dilatancy and fluid diffusion processes taking place in the rock medium at the earthquake source, magnetic effects should be given rise.Preliminary calculations under simplified assumptions show that the space distribution on the basis of dilatancy-magnetic effect agrees rather well with the distribution of the magnetic variations actually observed. Some earthquake examples are illustrated.