Spatial Distributions of the Induced Seismicity in the Upper Silesian Coal Basin

The Upper Silesian Coal Basin is the region where the great seismic activity is observed. The most of seismic events have the energy not exceeding 107 J. Their localisation and character suggest the connections with generation of new discontinuities in rock mass, induced by mining activity. The tremors with higher energy are also registered but their frequency is much lower. In the time interval 1977— 1994 there were 3882 tremors with energy equal to 106 J or more occurring in the studied area, but only 395 of them have energy not less than 107J. The flow of regional tectonic processes on origination of the strongest seismic events is postulated by some authors investigating the induced seismicity of the USCB. The spatial distribution of tremor epicentres is not uniform in the USCB area. Despite of mining activity carried out in all this area tremor epicentres concentrate in four regions connected with different geological units. Inhomogenity of tremor spatial distribution suggests the fractal character of seismic phenomena. The temporal variability of tremor epicentre co-ordinates shows some kind of “strange attractors”. These facts could point that induced seismicity in the USCB is triggered by non-linear dynamical process, having the regional meaning and connected with recent tectonic activity

Unification of data from various seismic catalogues to study seismic activity in the Carpathians Mountain arc

The CarpathianMountains arc is the most seismically active area in Central Europe. Analysis of the seismicity of entire Carpathian arc requires data from each of the particular catalogues which have to be properly and uniformly entered, standardized and merged. For our study we first had to prepare a database of seismic events (ML 1.6) compiled from the data of earthquakes taken from individual national seismic networks as well as data from international seismic centers. However, a careful review of these catalogues has uncovered significant inconsistencies, particularly discrepancies in the description of the location, magnitude and completeness of seismic events. To address these inconsistencies, a newly created compound earthquake catalogue was compiled from the aforementioned seismic catalogues and included events that occurred in the Carpathian Mountains arc area between 1976 and 2017. This work is intended to point out some of the problems associated with collecting data from various seismic catalogues as well as the need for their very careful verification, in order to create a uniform set of seismic data across a large area spanning numerous countries. The results suggest that compiling a uniform and dependable earthquake catalogue is crucial for reliable seismic studies

The Changes of P-Wave Velocity of Rock Samples Over Time

The main aim of this study was to determine the variation of the P- wave velocity of carbonate rocks over time. Samples of carbonate rocks like dolomite and limestone were carried out from three quarries. The study was done in May and November 2015. To test equipment Pundit Lab+ was used, which measure the transmission time of ultrasonic wave. On the base on the transmission time P- wave seismic velocities were calculated. It allows to compare the results obtained for one time interval and to calculate, using the Student's t test, if differences of P- wave seismic velocity values are significant

Badanie rozkładu epicentrów silnych wstrząsów w Górnośląskim Zagłębiu Węglowym

Chociaż eksploatacja prowadzona jest na całym obszarze GZW, epicentra silnych wstrząsów grupują się w wydzielonych skupiskach. Skupiska te leżą w następujących subjednostkach strukturalnych GZW: — synklina Bytomia (niecka bytomska), — synklina Kazimierza (niecka kazimierzowska), — antyklina główna (siodło główne), — siodło główne — rejon Jaworzna, — synklina główna (niecka główna), — strefa fałdowa (Rybnicki Okręg Węglowy). Skupiska silnych wstrząsów oddzielone są od siebie obszarami asejsmicznymi, w których nie rejestruje się wstrząsów o takim zakresie energii, chociaż mogą tam występować niskoenergetyczne wstrząsy typowo eksploatacyjne, niewywołujące niszczących skutków ani w wyrobiskach górniczych, ani na powierzchni. Rozkład epicentrów silnych wstrząsów występujących w GZW nie zależy od skali, w której rozpatruje się ich lokalizację

Zjawiska sejsmiczne w Górnośląskim Zagłębiu Węglowym i ich charakterystyka

Opisane cechy zbioru silnych wstrząsów wskazują, że podział sejsmiczności GZW ze względu na kryterium energetyczne odpowiada podziałowi na zbiór wstrząsów, których przyczyną jest działalność górnicza i zbiór wstrząsów w powstaniu których mają udział procesy tektoniczne. Nie oznacza to, że żaden z silnych wstrząsów nie może mieć genezy eksploatacyjnej. Również w zbiorze słabych wstrząsów mogą występować zjawiska pochodzenia tektonicznego. Prawdopodobieństwa tych zjawisk wydają się jednak małe. Bezpośrednią przyczyną zjawisk sejsmicznych w GZW jest bez wątpienia naruszenie górotworu spowodowane działalnością górniczą. O ile jednak zbiór słabych wstrząsów można określić jako sejsmiczność indukowaną, to silne zjawiska sejsmiczne zależą od czynników tektonicznych, a eksploatacja górnicza jest dla nich swoistym "mechanizmem spustowym" wyzwalającym i stymulującym aktywność sejsmiczną. Model sejsmotektoniczny, którego głoównym założeniem jest istnienie aktywnej strefy rozłamowej w głębokim podłożu GZW przedstawił L. Teper (1998). Szczegółowe dane i wyniki badań rozkładów silnych wstrząsów w GZW oraz próby ich wyjaśnienia w oparciu o model sejsmotektoniczny znaleźć można w pracy A. Idziaka, L. Tepera i W.M. Zuberka (1999)

Zastosowanie nowoczesnych metod geofizycznych w monitoringu i inżynierii środowiska

"Skażenie środowiska naturalnego przejawia się zmianami własności fizykochemicznych składających się na nie elementów: gleby, skał i wody. Geofizyka, jako nauka badająca własności fizyczne geosfery, posługuje się szerokim wachlarzem metod badawczych, które mogą być stosowane w ochronie środowiska. Duża czułość i dokładność współczesnych przyrządów geofizycznych, możliwość zautomatyzowania pomiarów, rozwój metod interpretacji i prezentacji wyników badań sprawiają, że pomiary geofizyczne stanu środowiska stosowane są coraz powszechniej." (fragm.

Anizotropia prędkości fal sejsmicznych i jej związek z orientacją systemów spękań masywów skalnych

Fracturing is one of the fundamental characteristics of the Earth crust. It has a governing influence on many physical properties of the rock massifs. Due to the importance of fracturing, of great significance becomes the feasibility of determining crack parameters in massifs which are not directly accessible for geological observations. Joint exert a particularly marked influence on the elastic properties of the rocks and hence on the seismic wave velocities. The existence of this relation makes it possible to use of seismic methods for determining the crack density and the orientation of crack systems. In these studies the objective was to determine the relationship between crack anisotropy and seismic wave velocity anisotropy using of the most up to date interpretation method based on tensor calculus. The concept of crack tensor developed by Oda (1984, 1986) was modified so as to give it a specific physical sense. At the same time the constituent equation was also modified and in this way the values of elastic constants calculated from the crack distribution corresponded to values found by seismic methods. A detailed analysis was made of the two-dimensional crack tensors and velocity tensors in the transversely isotropic medium. Their characteristic features were shown on the model distributions of velocities and cracks. From the results of experimental tests carried out in carbonate massifs of varied ages lying in the eastern and north — eastern part of the Upper Silesian Coal Basin it was possible to verify the theoretical model developed, by establishing the relations between the components of crack tensors and velocity tensors in the massifs considered. A procedure was developed for determining joint distributions from seismic measurements. Obtained results can be utilized in tests of jointed rocks inaccessible for direct observations

Ground-motion prediction equation and site effect characterization for the central area of the Main Syncline, Upper Silesia Coal Basin, Poland

The aim of the study was to find the best model of ground-motion prediction equation (GMPE) forecasting peak ground acceleration (PGA) caused by induced seismicity. The maximum values of PGA on the surface are a major seismic threat for the infrastructure, especially in the highly urbanized areas, such is the Upper Silesian Metropolitan Area. The forecasting equations were estimated based on the values of PGA, epicenter distances and mining tremor energy registered by 14 surface seismometer stations located in the central area of the Main Syncline of the Upper Silesia Coal Basin. Data were collected within the period from January 2010 to December 2016, and the total number of seismic events used in the calculations was 15 541. The final model predicted the PGA values and amplification coefficients representing the characteristics of the site effects under seismometer stations

Uncertainty based multi-step seismic analysis for near-surface imaging

Near-surface seismic surveys are often designed for surface wave and seismic tomographic analysis. In recent years, seismic imaging methods have been more frequently used at this scale. Recognition of near-surface structures using a single method is insufficient because of the ambiguity of the inversion problem. As a solution, the authors propose a multi-step approach, where several different seismic methods are used in a particular order, to achieve an optimal model. A multi-method approach allows utilisation of awhole spectrum of recorded data, even the elements that are treated as background noise in other techniques. In classical processing approach, information about data uncertainty is often omitted or used in the simplest way for the single method only. This work presents an updated approach to uncertainty analysis by transferring estimated uncertainty between processing steps. By assuming that every consecutively applied method is more certain, the authors were able to obtain accurate velocity fields for seismic imaging, as the main information received from the previous steps. Based on information from multiple methods, a seismic stack in the depth domain was created as a final result, with an estimate of uncertainty

Study on energy distributions of strong seismic events in the USCB

The paper presents the statistical analysis of energy distribution of strong seismic shocks (energy E ≥ 105 J) occurred in the Upper Silesian Coal Basin which is one of the most seismically active mining areas in the world. In the USCB tremor epicenters do not occur uniformly throughout the whole basin but group in several regions belonging to different structural units and are separated by regions where strong shocks are not observed. The aim of the studies was to determine the modality of the energy distributions and to compare the modal types in regions of the USCB where the shocks epicenters cluster. An analysis was made for shocks with energies equal to or greater than 105 J recorded by Upper Silesian Regional Seismological Network operated by Central Mining Institute (CMI), which took place between 1987 – 2012. The analysis has proven the bimodality of seismic energy distribution in the three of five studied areas of the Upper Silesian Coal Basin. The Gumbel’s distribution II type best fit the experimental energy distribution for almost all studied tectonic units except the main syncline area, where the Gumbel’s distribution I type matched better the low-energy mode. This is due to too short time window, causing a shortage of the strongest shocks in seismic catalogue