A search for the slow initial phase generated by seismic events at a copper mine in Poland
Observation of seismic events induced by mining activity at the Rudna copper mine allowed to identify the occurrence of the Slow Initial Phase on the seismograms. A total of 4384 seismograms from 137 seismic events were analyzed. The seismic moment of the strongest event was 3.36x10(14) N.m and that of the smallest was 2.66x10(11) N.m. the Slow Initial Phase was noted on 182 seismograms, visiblein order to remove the influence as a gradual and extremely slow increase of the signal amplitude directly before the P-wave first arrival. This increase could be related to the attenuation of the signal propagating from the source to the receiver. In order to remove the influence of inelastic signal attenuation on the path from the source to the receiver, of the recording equipment and of other factors on the initial part of the seismograms of the analyzed events, numerous simulationswere carried out, allowing for appropriate corrections to the duration time of the Slow Initial Phase. These corrections did not have any significant impact on the final results, which leads to the conclusion that the Slow Initial Phase originates in the seismic source and is not effect related to the propagation of the wave from the source to the station.
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