Identification of seismic doublets occurred on Rudna mine, Poland

Seismic events with similar focal mechanisms and similarity of Green's functions exhibit common waveform shapes recorded on the same seismic station. The similarity of seismograms can also be observed in the case of man-induced seismicity on the continuous excavated area. In this work, we focused on strong and potential mining-induced seismic doublets, our study was using concepts of signal analysis, using an in-mine network with quite low dynamic range. Since in such case records for strong events are usually affected by clipping, signal analysis were performed with both raw signal cross-correlation (CC) and binary signal cross-correlation (BCC). We found that for events which fulfilled the established criteria, waveform similarities are significantly higher than for other possible doublets. Using BCC and CC approaches, we noticed crucial influences of double couple nodal planes' as well as P and T axis orientations on waveform similarities although the focal mechanisms were characterized by very high non-double couple components. Finally analysis confirmed that human activity represented by mining is able to produce strong (M > 3) repeating mining tremors.