Wyniki wyszukiwania - Biblioteka Nauki

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Studies of short and long memory in mining-induced seismic processes

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Węglarczyk S. , Lasocki S.

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tom Vol. 57, no. 3

696-715

EN

Memory of a stochastic process implies its predictability, understood as a possibility to gain information on the future above the random guess level. Here we search for memory in the mining-induced seismic process (MIS), that is, a process induced or triggered by mining operations. Long memory is investigated by means of the Hurst rescaled range analysis, and the autocorrelation function estimate is used to test for short memory. Both methods are complemented with result uncertainty analyses based on different resampling techniques. The analyzed data comprise event series from Rudna copper mine in Poland. The studies show that the interevent time and interevent distance processes have both long and short memory. MIS occurrences and locations are internally interrelated. Internal relations among the sizes of MIS events are apparently weaker than those of other two studied parameterizations and are limited to long term interactions.

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Relacja tłumienia wartości szczytowej przyspieszenia drgań gruntu z uwzględnieniem amplifikacji dla wybranych rejonów obszaru LGOM

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Olszewska D. , Lasocki S.

WUG : bezpieczeństwo pracy i ochrona środowiska w górnictwie

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2006

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tom nr 6

19-20

PL

W oparciu o dane sejsmometryczne z 14 stanowisk znajdujących się na terenie Legnicko-Głogowskiego Okręgu Miedziowego badano tłumienie wartości szczytowej drgań gruntu w zależności od odległości od źródła, energii źródłowej i lokalnego wzmocnienia. Na podstawie przyjętego modelu wyznaczono relacje tłumienia przyspieszenia drgań gruntu składowej poziomej z uwzględnieniem amplifikacji. Przyjęty model na podstawie rejestracji ze wszystkich stanowisk pozwala na wyznaczanie współczynników reprezentujących zależność od odległości epicentralnej i energii wstrząsu oraz wyznaczenie indywidualnych współczynników opisujących lokalne wzmocnienie na każdym ze stanowisk. Tak wyznaczone względne współczynniki wzmocnienia, w odniesieniu do warunków lokalnych na jednym ze stanowisk, zostały porównane ze współczynnikami amplifikacji wyznaczonymi na podstawie metody HVSR.

EN

The data from 14 seismometer station located on Legnica-Glogow Copper District is used to study the attenuation of ground peak acceleration due to epicentre distance, source energy and site effects. The attenuation relation is estimated using the model which implicate factor of amplification. This model give opportunity to estimated factor of epicenter distance and source for all data and also estimated the individual amplification factor of each station. Those amplification factor obtained using regression model are being compeer witch amplification factor based on HVSR method.

3

Bias, variance and computational properties of Kijko’s estimators of the upper limit of magnitude distribution, Mmax

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Lasocki S. , Urban P.

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tom Vol. 59, no. 4

657-658

EN

It is often assumed in probabilistic seismic hazard analysis that the magnitude distribution has an upper limit Mmax , which indicates a limitation on event size in specific seismogeneic conditions. Accurate estimation of Mmax from an earthquake catalog is a matter of utmost importance. We compare bias, dispersion and computational properties of four popular Mmax estimators, introduced by Kijko and others (e.g., Kijko and Sellevoll 1989, Kijko and Graham 1998, Kijko 2004) and we recommend the ones which can be the most fruitful in practical applications. We provide nomograms for evaluation of bias and standard deviation of the recommended estimators for combinations of sample sizes and distribution parameters. We suggest to use the bias nomograms to correct the Mmax estimates. The nomograms of standard deviation can be used to determine minimum sample size for a required accuracy of Mmax.

4

Seismicity of Czorsztyn Lake Region : A Case of Reservoir Triggered Seismic Process?

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Białoń W. , Zarzycka E. , Lasocki S.

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tom Vol. 63, no. 4

1080--1089

EN

Czorsztyn Lake is an artificial water reservoir backed up by the hydropower plant Niedzica earth dam on Dunajec River in south Poland. Its filling began in 1995 and ended in 1997. The reservoir of 234.5 million m3 capacity is shallow, between 20 to 50 m of water column, on average. Until 2011 the seismic activity in this region was sparse, some 1 event trimonthly. However, in November 2011 more than 60 events occurred. Such bursts of activity, separated by low activity periods, continue to appear. Since August 2013 the area is monitored by a local seismic network. The setup allows to accurately locate the epicenters and to determine source mechanisms for stronger events. The events are clustered and aligned along NE-SW direction and their mechanisms are very similar, indicating N-S strike slip faulting. This and the irregular pattern of activity suggest that this seismicity is triggered by the reservoir impoundment.