The mutual inductance of any two coaxial circular coils and the distribution of the magnetic induction line from the system;

Discussion on the mutual inductance M_(12 )=M_(21);

The approximate analytic formula of the mutual inductance between two loops with the same axis and size and that of their interaction;

The directives concerning the protection of telecommunication lines against harmful effects from electricity lines specified by Comite Consultatif Internationale de Telegraphique et Telephonique (CCITT) give basic representation of mutual inductance coefficient which contains infinite integral.

This paper deduces the general result that the mutual inductance coefficient can be ne- glected when two infinitely long and straight solenoids in connected series from the theoreti- cal calculation and corrects the mistakes which appeared in some papers when the problem was discussed.

Direct proof for the coefficient of mutual inductance M_(21)=M_(12);

There is only one coefficient of mutual inductance about two round roads L_1 and L_2,i.

A simple and convenient method of direct proof for the coefficient of mutual inductance is given.

1) in Dayao, Yunnan in 2003 using cross-correlation coefficient method, after determining the high-resolution hypocentral locations of the earthquake sequences using the double-difference earthquake location algorithm.