On the connection between the critical value of the "vertical" electrical anisotropy and earthquake prediction |
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Authors: | VM Luboshits |
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Institution: | Institute of Physics of the Earth, Academy of Sciences USSR, Bolshaya Grouzinskaya 10, Moscow 123810, USSR |
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Abstract: | Summary. It is shown that at any orientation of a dipole of direct current at the surface of a uniform anisotropic halfspace there exists a unique critical value ηcr of the "vertical" electric anisotropy η. For η > ηcr not all field lines are closed, and three straight field lines pass through the centre of the dipole. Also there exists a unique value ηeq > ηcr, where equatorial η is equal to zero. If η > ηeq then equatorial ρapp is negative since the electric vector is turned more than through 90° at the equator of dipole, and it is shown that ηcr= 1.79, ηeq= 1.93 if the axis of dipole is directed symmetrically with respect to the axes of anisotropy. Routine observations of variations of ρapp with the aim of earthquake prediction should be carried out taking into account the possibility of great fluctuations on η far from the epicentre of an earthquake. |
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