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Local Seismic Events in the Area of Poland Based on Data from the PASSEQ 2006-2008 Experiment

Polkowski M., Plesiewicz B., Wiszniowski J., Wilde-Piórko M.

Acta Geophysica

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2016

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Vol. 64, no. 6

2092--2113

EN

PASSEQ 2006-2008 (Passive Seismic Experiment in TESZ; WildePiórko et al. 2008) was the biggest passive seismic experiment carried out so far in the area of Central Europe (Poland, Germany, the Czech Republic and Lithuania). 196 seismic stations (including 49 broadband seismometers) worked simultaneously for over two years. During the experiment, multiple types of data recorders and seismometers were used, making the analysis more complex and time consuming. The dataset was unified and repaired to start the detection of local seismic events. Two different approaches for detection were applied for stations located in Poland. The first one used standard STA/LTA triggers (Carl Johnson’s STA/LTA algorithm) and grid search to classify and locate the events. The result was manually verified. The second approach used Real Time Recurrent Network (RTRN) detection (Wiszniowski et al. 2014). Both methods gave similar results, showing four previously unknown seismic events located in the Gulf of Gdańsk area, situated in the southern Baltic Sea. In this paper we discuss both detection methods with their pros and cons (accuracy, efficiency, manual work required, scalability). We also show details of all detected and previously unknown events in the discussed area.

2

Seismic event near Jarocin (Poland)

Lizurek G., Plesiewicz B., Wiejacz P., Wiszniowski J., Trojanowski J.

Acta Geophysica

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2013

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Vol. 61, no. 1

26--36

EN

The earthquake of magnitude ML= 3.8 (EMSC) took place on Fri- day, 6 January 2012, north-east of the town of Jarocin in Wielkopolska Region, Poland. The only historical information about past earthquakes in the region was found in the diary from 1824; apart of it, there was a seismic event noticed in the vicinity of Wielkopolska in 1606 (Pagaczewski 1982). The scope of this paper is to describe the 6 January 2012 event in view of instrumental seismology, macroseismic data analysis and known tectonics of the region, which should be useful in future seismic hazard analysis of Poland.

3

Seismic event of January 22, 2010 near Bełchatów, Poland

Wiejacz P., Rudziński Ł.

Acta Geophysica

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2010

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Vol. 58, no. 6

988-994

EN

The paper summarizes the findings about a seismic event on January 22, 2010, near Bełchatów, Poland, in terms of data, event location, magnitude and source parameters.

4

Podhale, Poland, earthquake of November 30, 2004

Wiejacz P., Dębski W.

Acta Geophysica

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2009

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Vol. 57, no. 2

346-366

EN

Earthquake of November 30, 2004, in Podhale region, southern Poland, was of unexpectedly big size in this area of weak seismicity. As Poland is considered a country of low seismicity, the earthquake has caused concern about seismic hazard in Poland, especially since it took place shortly after the even more unexpected Kaliningrad Region, Russia, earthquakes of September 21, 2004, that inflicted minor damage in northern Poland. The paper presents the findings on the Podhale earthquake which reached macroseismic intensity up to 7 and magnitude 4.7 (mb; ISC). The event was felt up to a distance of about 100 km and inflicted slight damage to buildings in its narrow epicentral area, thus evidencing its relatively shallow depth. The quake has been located near the village of Skrzypne, about 15 km west-southwest of the district capital Nowy Targ. The source mechanism has been found to be of dip slip normal fault type, although a problem remains of association of this mechanism with known tectonic dislocations in the region. The earthquake has been followed by a long series of aftershocks. Their distribution in time is also studied and the biggest aftershocks have been located.

5

Moment magnitude determination of local seismic events recorded at selected Polish seismic stations

Wiejacz P., Wiszniowski J.

Acta Geophysica

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2006

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Vol. 54, no. 1

15-32

EN

The paper presents the method of local magnitude determination used at Polish seismic stations to report events originating in one of the four regions of induced seismicity in Poland or its immediate vicinity. The method is based on recalculation of the seismic moment into magnitude, whereas the seismic moment is obtained from spectral analysis. The method has been introduced at Polish seismic stations in the late 1990s but as of yet had not been described in full because magnitude discrepancies have been found between the results of the individual stations. The authors have performed statistics of these differences, provide their explanation and calculate station corrections for each station and each event source region. The limitations of the method are also discussed. The method is found to be a good and reliable method of local magnitude determination provided the limitations are observed and station correction applied.

6

Time changes in dominant trends of epicentre migration for local seismicity from a mine

Kustowski B.

Acta Geophysica Polonica

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2000

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Vol. 48, nr 4

455-464

EN

Time variations of trends of epicentre migration for a local seismicity induced by mining operations at Wujek coal mine in Poland were studied. We investigated whether these variations are non-random and reflect time changes of the factors controlling seismic events generation. The trends of epicentre migration are described by the distribution of deflection, that is, the azimuth of straight line connecting epicenters of every two consecutive events in a seismic series. The probability density function of deflection, estimated by the nonparametric kernel method, indicates the multidirectionality of migration. Moreover, the dominant directions change systematically with time in a certain correlation with strong event occurrences.