Source parameters of seismic events at Polkowice copper mine and certain problems related to their estimation

Source parameters of seismic events at Polkowice copper mine and certain problems related to their estimation

GEOLOGYEARTHQUAKES 968032 Okrwlaaie sejsmicznego w op8rcio 0 parrmetry mecbrnizmu ogdsk wstrzasow gorniczycb (Assessment of seismic hazard from the f...

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GEOLOGYEARTHQUAKES 968032 Okrwlaaie

sejsmicznego w op8rcio 0 parrmetry mecbrnizmu ogdsk wstrzasow gorniczycb (Assessment of seismic hazard from the focal mechanism parameters of mhing tremors) J. Dubinski & K. Stec, Publications - Institute of Geophysics, Polish Academy of Sciences, series M, M-19(281), 1995, pp zagrozmia

57-71. Seismic methods used in the Polish coal mining are limited to

determining the co-ordinates of seismic events and their energy. Studies have been undertaken to extend the set of interpretation parameters, to include the angles describing the spatial orientation Of the fault plane, as well as parameters describing the location of the principal stress axes. These parameters are determined with the help of an algorithm, using the first-motion data of P waves recorded on the seismogram. It is shown that the extended set of parameters describing the focal mechanism of seismic events implies a clear connection with the geological and tectonic conditions of mining operations and the resultant seismic hazard. (from English summary) 968033 Estimation of stresses for tbe mining-induced sequences of seismic events R. Teisseyre Jc P. Wiejacz, Publications - Institute of Geophysics, Polish Academy 19(281), 1995, pp 5-14.

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968034 Prognozoranie metodn analityczna wydatku energetycznego wstrzasow indukowanycb w gorotworze deformowanym eksplortacja wielopokladowa (Analytical prediction of energy release of seismic events induced in tbe rock mass deformed by multi-level extraction) J. Bialek, B. Drzezla & A. Jaworski, Publications - Institute of Geophysics, Polish Academy 19(281), 1995, pp 115-123.

and a rate of advance of excavation are studied. The studies reveal that changes of the advance rate do not have any influence on the b variations. (from English summary) 968036 Analysis of b-value in tbe frequency+nergy distributions K. Holub, Publications - Institute of Geophysics, Polish Academy of ‘Sciences, series M, M-19(281), 1995, pp 153-161. Using the database of the operational center of the local seismological network in the Ostrava-Karvina District and applying software adopted for statistical analyses, the frequency-energy distributions were investigated. It was found that individual relations defined by the formula log N = a - b log E display a specific character due to the parameter b which generally defines the ratio of weak and strong seismic events. In this sense, increasing seismic hazard in mining workings corresponds to the decreasing b-value in the frequency-energy distribution, valid for a given region under investigation. (from Author) 968037 Zastosowanie apriorycznej informecji typu dyrektywa (D) do loknlizacji kopalnianycb zjawisk sejsmicznycb (The application of a priori information of directive type (D) for the location of seismic events in mines) P. Kolodziejczyk & K. Wanat, Publications - Institute of Geophysics,

Develops the method introduced by Teisseyre and Wiejacz (1993), which gives stress estimation for sequences of seismic events with foci localized in a well confined region. The method is based on some inequality conditions including values of stress drop, seismic moment and energy (calculated independently). These conditions interrelate the stress values of the consecutive events. Discussion proves that the stress estimation can be quite accurate. Assuming a linear increase of stresses between the events (from the value after the stress drop to that just before the next event), we get a full diagram of stress pattern of the mining-induced sequence of events. Seismic efficiency can be estimated too. (Authors)

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The paper presents basic assumptions and up-to-date results of analytical studies on the prediction of total energy release and the number of tremors induced as a result of multi-level extraction. Relations for the calculation of deformation energy increase are given, making it possible, after the specification of parameters, to predict density distribution of tremor energy (in J/m2 and J/m3) ahead of the designed longwall. Examples of the prediction calculations for a given mining area are presented. (English summary) 968035 Zwiazek bazardu sejsmicznego z predkoscin postepu frontu gorniczego (Relations between tbe seismic hazard and the rate of advance of mining front) S. Lasocki, Publications - Institute of Geophysics, Polish Academy of Sciences, series M, M-19(281), 1995, pp 145-152. Seismicity induced by mining in a stope area follows the Gutenberg-Richter relation. Parameter b of the relation, which varies in time with changes of conditions of tremor generation, is related to seismic hazard in the area - the probability of strong event occurrence increases when the value of parameter b drops down. Correlations between the time dependent b value and other parameters of seismicity

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19(281), 1995, pp 141-144. In the new methods of solving the location problem, regularization methods of calculation algorithms are used in order to limit the errors of data and the influence of numerical disturbances. The introduction of a priori information, about a seismic event improves the stability of the location process. A solution applying a priori information of the probabilistic type is known in the literature. In this paper the application of a priori information of a directive type is described. The possibility of applying a numerical method of problem embedding in relation to traditional algorithms of locating mining events is pointed out. (English summary) 968638 Parametry ognisk wstrzasow gorniczycb w kopahi miedzi Polkowice oraz niektore problemy zwiazane z icb wyznaczaniem (Source parameters of seismic events at Polkowice copper mine and certain problems related to tbeir estimation) M. Krol, Publications - Institute of Geophysics, Polish Academy of Sciences, series M, M-19(281), 1995, pp 197-207. Data acquisition and processing system employed by the digital seismic network at Polkowice copper mine is presented. Data presentation and collection are also described. Certain problems related to the estimation of source parameters of recorded mining tremors are discussed. (English summary) 968039 Source mechanisms of seismic events indoced at Ziemowit coal mine: comparison with mining information P. Wiejacz, Publications - Institute of Geophysics, Polish Academy of Sciences, series M, M-19(281), 1995, pp 15-32. This work presents the results of seismic moment tensor calculations for mine tremors at Ziemowit coal mine. A total of 58 events were analyzed. Source mechanisms were calculated by amplitude inversion in time domain using first P wave onset amplitudes. The full, pure deviatoric and double-couple tensors have been calculated using L2 norm. The results were compared with the mining situation. This comparison has lead to reasoning that the vertical source locations given by the mine might be wrong. The results were then recalculated for the case of seismic sources at the mining level. Although the seismic activity seems connected to mining features, the mechanisms were not found to clearly correlate with their directions. (Author)