## 2 Materials and Methods
### Data and Sensors  
The Upper Silesian Coal Basin, known as a seismically active mining area, is mainly characterized by two general types of events: mining-related and mining-tectonic seismicity [32]. Seismic events exclusively associated with mining have relatively low energy and occur near mine roadways. In contrast, tectonic-related events generally have higher energy and are generated in dislocation zones, often far from mine working sites. The focal mechanism of mining seismicity events is generally characterized by a relatively small shear component compared to the explosive and compressional components. The opposite situation was noticed in the case of the mining-tectonic seismicity, where the shear component reached 70% of the total seismic moment tensor solution, corresponding to the double-couple source mechanism. The seismic signals from the seismic data collected at both sites were characterized by peak motion values at the S-wave phase. They were, therefore, considered to be the effect of mining-tectonic seismicity. During the seismic observations, 60 events occurred at the IMI station site. The strongest of these, whose local magnitude reached ML 2.7, occurred on 24 June 2015. In the catalogue, the local magnitudes of the events range from 1.7 to 2.7 at distances ranging from 0.74 to 5.6 km (Table 1). All event sources were located in the SSW direction with respect to the seismological station. Relatively large events occurring at a short distance of only 1 km from the seismological station in Imielin result in a high resolution of the seismic signal (Figure 2a). Seventy events were noticed at the field of the PLA station. The strongest one occurred on 3 June 2016, and its magnitude reached ML 3.4. The catalogue contains events with local magnitudes ranging from 2.5 to 3.4 at a distance ranging from 5.7 to 20.4 km (Table 1). The event sources are located mainly in the NEE direction relative to the seismological station. The distance between the source and the station is higher than in the IMI station, but the seismic energy is also relatively higher. Therefore, the signal resolution is comparable to the second station (Figure 2b). Each analyzed event (Figure 1c,e) was registered by the EENTEC measuring set, composed of the seismic recorder DR-4000 linked to the GPS module, translational accelerometer EA-120, and rotational seismometer R-1. EA-120 is a triaxial force-balanced accelerometer with a scale range equal to \(\pm\)2 g and a dynamic range equal to 128 dB. R-1 is a well-known triaxial rotational seismometer, the resolution of which is equal to 1.2 \(\times\) 10\({}^{-7}\) [rad/s], with a dynamic range equal to 110 dB, frequency band ranging from 0.05 to 20 Hz, and amplitude clip at the level of 0.1 rad/s at 1 Hz [33]. In the case of the PLA station, the sensors were mounted in the basement at a concrete pedestal, while in the IMI station, the sensors were deployed in a thin vault at 1.20 m depth. The temperature in both places was stable and lower than 18 \({}^{\circ}\)C, which helped \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & & \multicolumn{2}{c}{**IMI STATION**} & \multicolumn{2}{c}{**PLA STATION**} \\ \cline{3-6}
**Energy [J]** & \(\mathbf{M_{L}}\) & **Number** & **Epicentral Distance** & **Number** & **Epicentral Distance** \\  & & **Number** & **for the Energy Range [km]** & & **Range [km]** \\ \hline \(1.0\times 10^{5}\)–\(5.0\times 10^{5}\) & 1.7–2.0 & 35 & 0.75–5.13 & 0 & - \\ \hline \(6.0\times 10^{5}\)–\(9.9\times 10^{5}\) & 2.1–2.3 & 13 & 0.65–1.42 & 0 & - \\ \hline \(1.0\times 10^{6}\)–\(5.0\times 10^{6}\) & 2.4–2.5 & 7 & 1.17–5.52 & 22 & 5.68–18.99 \\ \hline \(6.0\times 10^{6}\)–\(8.5\times 10^{6}\) & 2.6–2.7 & 5 & 1.34–4.20 & 28 & 5.63–18.32 \\ \hline \(1.3\times 10^{7}\)–\(2.4\times 10^{7}\) & 2.8–2.9 & - & - & 12 & 5.67–20.43 \\ \hline \(3.2\times 10^{7}\)–\(7.6\times 10^{7}\) & 3.0–3.2 & - & - & 5 & 5.91–12.38 \\ \hline \(1.2\times 10^{8}\)–\(2.8\times 10^{8}\) & 3.3–3.5 & - & - & 3 & 8.20–9.70 \\ \hline \hline \end{tabular}
\end{table}