Positioning of seismic sources in multilayered horizontal or inclined media

In order to make full use of 3-D velocity structure of the rock mass in the mining area, based on the combined method of forward and inversion as an embryonic form, a new method for positioning of seismic sources in multilayered horizontal or inclined media is put forward. The wave front surface equation in multilayered horizontal media is derived. From the perspective of any field setup, based on the equation, the original time of earthquake is substituted into the nonlinear equations as an unknown quantity. The nonlinear equation set is established, of which the unknowns are equal to the number of nonlinear equations, thus a method for positioning of seismic sources based on forward of wave front is established. The time when the earthquake happens is obtained through inversion and corrected by curve fitting based on regular field setup in the positioning model combined with forward and inversion. The positioning model, based on forward of wave front, which deals with the time of earthquake as an unknown quantity in the nonlinear equations, is different. It obtains spatiotemporal parameters of seismic sources through nonlinear equations of four stations. The number of source parameters is reduced using the method of variable substitution, so the nonlinear system of the positioning model based on forward of wave front is simplified. The determination of iterative initial value is easier. The original geodetic coordinates of stations are rotated into those which are orthogonal or parallel to the interfaces between different media. The forward direction of wave front in the new coordinate system is parallel to the axis z. Thus the positioning model based on forward of wave front is extended to multilayered inclined media. The positioning model based on forward of wave front is an effective method to solve the problem of source positioning in multilayered inclined media. The calculated results of conditional numbers of 16 unknown parameters corresponding to 3 parameters of velocity structure under different conditions show that the conditional numbers of positioning model based on forward of wave front are all far less than 10, and the positioning model based on forward of wave front is in good state.