METHOD FOR LOCATING THE SPATIAL ORIGIN OF A SEISMIC EVENT OCCURRING IN A SUBTERRANEAN FORMATION

摘要

Method for locating the spatial origin of a seismic event within an underground formation The P and S wave arrival times are recorded by means of a triaxial sensor in the form of a seismic signal, on which the moment t P of the first arrival of the wave P and the period TP of this seismic signal. Then, the instant Ts of first arrival of the wave S is determined by defining a time window of analysis W, chosen so that the energy of the wave S is minimal within this window W. allows to correctly determine the direction of propagation of the P wave by means of an analysis of the polarization of the signal on the window W. The seismic signal is then projected into a new reference defined by the direction of propagation of the P wave. and two other perpendicular axes Np and B. It is thus possible to detect the instant ts of first arrival of the wave S in a plane defined by the axes Np and B. Finally, we locate the spatial origin of the seismic event to from the direction of propagation of the P wave and the arrival times of the P and S waves. Application in particular to the seismic monitoring of underground deposits.