Automatic Determination of Full Moment Tensor Solutions from P-wave First Motion Amplitudes

Standard microseismic monitoring nowadays focuses on event locations, but information on detailed source parameters is rarely extracted. The estimation of full moment tensor solutions of microearthquakes may provide valuable information on presence and geometry of faults as well as stress fields and changes thereof. Therefore, we included a full moment tensor inversion using automatically picked P-wave first motion amplitudes in addition to the computations of source spectra and related source parameters. We tested the routine using synthetic polarities and synthetic waveforms computed in a complex 3-D velocity model. In a first application, we investigated mining-induced seismicity in the Pyhäsalmi ore mine, Finland. Approximately 50% of the events show strong non-double couple components. Known explosions could be retrieved, being used as quality control of the method.