A Fast Evaluation of the Seismic Moment Tensor for Induced Seismicity

An original method is proposed for the evaluation of moment tensor components using time-domain calculations of low-frequency displacement amplitudes with the first-wave polarities attached. The technique is suitable for applications involving large amounts of data that require a fast response time, such as those encountered in the analysis of induced seismicity. Simulation tests indicate an excellent agreement with inversions based on the far more labor intense spectral processing. The overall results of waveform simulation analysis allow the conclusion that this inversion approach is reliable in retrieving the geometrical aspects of the seismic source. Inversions for the pure-shear mechanism and a general mechanism, including a tensile component, are shown to be robust for various wave-type solutions, under reduced array coverage, hypocentral mislocation, and the addition of Gaussian normally distributed noise. The influence of errors in first-arrival polarities and low-frequency displacement amplitudes are subsequently studied for a better understanding of the applicability limits.