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1

Comparison of the effects of anthropogenic seismic events and natural earthquakes on buried infrastructure network components

Rusek Janusz, Słowik Leszek, Tajduś Krzysztof

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2023

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Vol. 71, nr 6

art. no. e147347

EN

Mining tremors may have an impact on the safety risk of steel pipelines through their effects. It is therefore important to quantify the impact of a high-energy mining tremor in terms of strength. In addition, a comparison of the results obtained with the effect of a seismic tremor can illustrate the scale of such a hazard. Recently, this has been a very frequently raised issue in the area of surface protection against negative mining impacts and the protection of post-mining areas. Ensuring safe use is particularly important for gas transmission elements. This paper presents the results of a comparative analysis of the impact of mining tremors and seismic impacts on a specimen steel pipeline segment. The analyzed pipeline is located in the eastern part of Poland in the area of paraseismic impacts of the LGCD (Legnica-Glogow Copper District) mine. For this purpose, an analytical approach was used to assess the impact of seismic wave propagation on underground linear infrastructure facilities. Accelerogram records for the 02-06-2023 seismic tremor from Turkey and the mining tremor for 11-25-2020 were used. In the case of the design of underground pipelines, the cross-section of the element for which measures describing wall stress and the ovalization of the cross-section are determined is usually considered. In the situation of the influence of seismic wave propagation or so-called permanent ground deformation, the response of the pipeline in the longitudinal direction is analyzed. As a final result, longitudinal strains transferred to the pipeline as a consequence of the propagating seismic wave and mining tremor were determined. The absolute difference between the deformations in the ground and along the length of the pipeline was determined. This type of analysis has not been carried out before and provides new insights into the topic of paraseismic impacts on the scale of their interaction with natural earthquakes. Mining tremor data was obtained from the mine’s seismological department. The seismic tremor data, on the other hand, was downloaded via the publicly available ESM (Engineering Strong- Motion Database).

2

Qualitative relationship of seismic activity with vertical displacements of terrain after mine closure with the use of DInSAR technology

Sopata Paweł, Sokoła-Szewioła Violetta

Geoinformatica Polonica

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2022

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T. 21

83--93

EN

The liquidation process of mines is very complex and long. It relates to various hazards, including post-mining seismicity and deformations of ground surface. The above issues are the subject of the research project under which the monitoring of ground surface movements is carried out in the area of the closed coal mine “Kazimierz-Juliusz”, which is currently being flooded. The monitoring is carried out using the GNSS technique and satellite radar interferometry (InSAR). The project makes use of radar data from the Copernicus project, which is being implemented by the European Commission in cooperation with the European Space Agency (ESA). InSAR monitoring started in December 2020. Additionally, we analyzed the impact on ground surface of 5 rock tremors of the energy not exceeding 6.5E + 05 J (tremor magnitude Mw = 2.1), which were reported in the investigated area in 2018–2020. The article presents the results of qualitative analysis involving the relationship between seismic activity and vertical movements of ground surface. To investigate potential changes in altitude, DInSAR technology was applied. On the basis of interferometric images generated from radarograms in the periods before and after the tremor, in January 2019, it was found that vertical movements of ground surface were possible to occur. Altitude changes can be characterized with the values in the range of single millimeters, which are only slightly beyond the accuracy range of the InSAR method. The analysis of interferograms, comprising wider time databases, indicated that the impact of the tremor on the deformations of ground surface is incidental.

PL

Proces likwidacji kopalń jest bardzo złożony i długotrwały. Towarzyszą mu różne zagrożenia, wśród których można wymienić sejsmiczność pogórniczą oraz deformacje powierzchni terenu. Problematyka ta jest przedmiotem projektu badawczego, w ramach którego wykonywany jest monitoring ruchów powierzchni na terenie nieczynnej już kopalni „Kazimierz-Juliusz”, która jest obecnie zatapiania. Monitoring realizowany jest z wykorzystaniem techniki GNSS oraz satelitarnej interferometrii radarowej (InSAR). W projekcie wykorzystywane są dane radarowe z projektu Copernicus, który realizowany jest przez Komisję Europejską we współpracy z Europejską Agencją Kosmiczną (ESA – European Space Agence). Monitoring techniką InSAR rozpoczęto w grudniu 2020 roku. Dodatkowo przeanalizowano powierzchniowe skutki pięciu wstrząsów górotworu o energii nieprzekraczającej wartości 6,5E+05 J (magnituda wstrząsu Mw = 2,1), które zarejestrowano w rejonie badań w latach 2018–2020. W artykule przedstawiono wyniki analizy jakościowej związków aktywności sejsmicznej z ruchami pionowymi powierzchni terenu. W celu zbadania potencjalnych zmian wysokościowych wykorzystano technologię DInSAR. Na podstawie obrazów interferometrycznych wygenerowanych z radarogramów w okresach przed i po wstrząsie, w styczniu 2019 roku, stwierdzono możliwość wystąpienia pionowych ruchów powierzchni terenu. Zmiany wysokościowe scharakteryzować można wartościami w zakresie pojedynczych milimetrów, wykraczających tylko nieznacznie poza zakres dokładności metody InSAR. Analiza interferogramów, obejmujących szersze bazy czasowe, wskazała na incydentalny wpływ wstrząsu na deformacje powierzchni terenu.

3

Spatial analysis of b-value variability in Elazig city and the surrounding area (Eastern Turkey)

Polat Gulten

Acta Geophysica

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2022

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Vol. 70, no 1

15--25

EN

Frequency-magnitude distribution was investigated in Elazig city and the surrounding area (coordinates ranging from 38.1° N to 39° N for latitudes and 39° E to 40° E for longitude) to reveal the present-day crustal stress within the region. For this study, a complete set of 5603 earthquakes of Md≥1 from 1 January 2000 to 31 August 2020 were localized from the Bogazici University, Kandilli Observatory and Earthquake Research Institute, Regional Earthquake-Tsunami Monitoring Center (KOERI) catalogue. For the whole study region, spatial mapping of the frequency-magnitude distribution was thus produced. The frequency-magnitude distribution (b-value) for seismicity within the study area was not homogeneous. Outstanding variations in the b-value were detected with b ranging from b≈slightly more than 0.3–2. In this region, low b-values are mostly dominant in the region except for a few local areas. This study also shows that accumulated stresses are high particularly at the Pütürge segment in contrast to the fault drawn in the south, which represents the main thrust belt that runs through Hani-Lice and stretches to Çüngüş. As expected, stress accumulation in reverse faults is fairly higher. However, the sharing of the tension formed in the compression zone of the Arabian Plate and the Anatolian plate (i.e. stress partitioning in a sense), results in a low share in the reverse fault belt.

4

Gravity field changes during deep exploitation of the coal longwall and their relation to stress distribution and seismic activity

Kortas Łukasz

Journal of Sustainable Mining

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2021

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Vol. 20, iss. 4

228--239

EN

Mining operations cause volumetric deformations within the rock mass and changes in its density, to which the gravimetric method is sensitive. These changes are particularly well seen in periodic measurements of the local gravity field. The paper analyses the relationship between the movement of a longwall in a coal seam and the change in the distribution of the gravity field in time and space observed on the ground surface. Relative gravimetric measurements were carried out in six series between 2018 and 2020; before the start of coal extraction, with the progress of the longwall and after the cessation of mining. Collected data allowed differential maps of changes in gravity to be plotted. Differential anomalies between the subsequent measurement series, and the reference one were then analysed. The distribution and temporal variations of the anomalies suggest a relationship between changes in density distribution of the rock medium in the longwall overburden, and the change in the stress state in the rock mass caused by the passage of the longwall front. An attempt was made to relate the variability of the state of stresses in the longwall overburden to the intensity of seismic tremors with energy > 10-4 J accompanying longwall exploitation.

5

Vibration and seismicity monitoring in dam control process

Rudolf Tomas

Gospodarka Wodna

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2021

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Nr 11

19--24

EN

Hydraulic structures, dams and technological equipment are exposed to dynamic loads which are caused by natural seismicity and technical seismicity. Measurement of induced vibrations and dynamic motions of structures can be used to find out more facts. It is an effective way to find out if the structure has been exposed to undesired stress or warn in time of possible exceedance of safety limits. Based on the measurement we can also assess the condition of technological equipment. The measurement can be used to assess the realized design of a structure or also as a basis for the design of reconstruction and improvements of constructions. The paper presents practical examples of measurements, conclusions and measures derived from them.

PL

Budowle hydrotechniczne, zapory i urządzenia technologiczne narażone są na obciążenia dynamiczne wywołane sejsmicznością naturalną oraz sejsmicznością techniczną. Pomiary drgań indukowanych i dynamicznych ruchów konstrukcji może posłużyć do poszerzenia wiedzy o budowli. Jest to skuteczny sposób na sprawdzenie, czy konstrukcja została narażona na niepożądane naprężenia lub bieżące ostrzeżenia o możliwym przekroczeniu granic bezpieczeństwa. Na podstawie pomiarów możemy również ocenić stan urządzeń technologicznych. Pomiary mogą być wykorzystany do oceny realizowanego projektu budowli lub jako podstawa do projektowania przebudowy i usprawnień konstrukcji. W artykule przedstawiono praktyczne przykłady pomiarów, wnioski i kroki podjęte na ich podstawie.

6

Afghanistan earthquake 2015 aftershocks analysis for a better understanding of the seismicity behavior for future assessment

Khalil Umer, Aslam Bilal, Maqsoom Ahsen

Acta Geophysica

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2021

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Vol. 69, no. 4

1189--1197

EN

Afghanistan has been subjected to many disastrous earthquakes in the past as it is situated in a seismically vigorous region. The converging edge of the Arabian, Indian, and Eurasian plates accounts for the high seismicity of the region. An Mw 7.5 earthquake hit northern areas of Afghanistan along with Pakistan on the October 26, 2015, with its epicenter positioned in the Hindu Kush (HK) region of Afghanistan at 45 km southwest of Jarm. Resulting in 115 deaths and impairment to 7679 buildings, the earthquake was of an intermediate depth (210 km), which was instigated from reverse faulting. In the current investigation, we investigated the instrumental earthquake data acquired from the multiple data sources for the period of ugust 4, 2015 to March 27, 2016 and from the main earthquake catalog; the aftershocks were classifed by exploiting Reasenberg’s algorithm. Numerous histograms of time, the hour of the day, depth, and magnitude have been formulated for explaining the disparity of aftershocks. The foremost inconsistency happens within the 3 days after a mainshock of the HK 2015 earthquake, as disclosed by the outcomes. The Gutenberg-Richter law was exploited to analyze the size dissemination of aftershocks, and the observed value of b is 1.02+/−0.06. In and around the epicenter of the HK 2015 earthquake, for the depiction of the decay proportions of aftershock sequences, Omori-Utsu law was exercised. The “p value,” which is the decay component, is computed to be 1.46+/−0.08.

7

Sejsmo-grawitacyjne sygnatury wstrząsów górniczych w ciągłych zapisach siły ciężkości grawimetrów pływowych gPhoneX

Kortas Łukasz

Przegląd Górniczy

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2020

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T. 76, nr 3

37--44

PL

W artykule przedstawiono wyniki obserwacji zmian pola grawitacji ziemskiej rejestrowanych w czasie występowania wstrząsów górotworu wywołanych podziemną eksploatacją węgla na terenie Górnośląskiego Zagłębia Węglowego. Zmiany pola grawitacji rejestrowane są w sposób ciągły przez dwa grawimetry pływowe gPhoneX zainstalowane w dwóch, różnych pod względem sejsmiczności górniczej rejonach Zagłębia. Jeden z grawimetrów zainstalowano w południowej części GZW, w rejonie kopalni ROW w Rybniku. Na tym obszarze odbywa się intensywna eksploatacja pokładów węgla na głębokości około 1 km. Ogniska wstrząsów powodowanych eksploatacją znajdują się w odległościach epicentralnych od 0 do 3 km od miejsca instalacji stacji grawimetrycznej, tj. w bliskim polu falowym zdarzeń sejsmicznych. Drugi grawimetr rejestruje zmiany siły ciężkości w północnej części GZW, na terenie pogórniczym w Katowicach, gdzie eksploatacja została dawno zakończona. Zarejestrowane przez ten instrument antropogeniczne zdarzenia sejsmiczne pochodzą z odległości od kilku do kilkudziesięciu kilometrów - z obszaru odległych aktywnych kopalń węgla, a tym samym z pola dalekich zdarzeń sejsmicznych. Celem artykułu jest analiza zbioru danych sygnałów sejsmo-grawitacyjnych pochodzących od wstrząsów górniczych zarejestrowanych przez grawimetry w okresie blisko 14 miesięcy, od listopada 2018 r. do grudnia 2019 r. w aspekcie ich przydatności do badania ruchów górotworu wywołanych sejsmicznością towarzyszącą eksploatacji. Wykonywane za pomocą układu grawimetrów pływowych mogą istotnie wzbogacić informację sejsmologiczną uzyskiwaną z tradycyjnych górniczych sieci sejsmologicznych w przedziale bardzo niskich częstotliwości ruchów górotworu.

EN

The article presents the results of observations of changes in the Earth’s gravity field recorded during the occurrence of rock mass shocks caused by underground coal mining in the Upper Silesian Coal Basin. Changes in the gravitational field are recorded continuously by two gPhoneX tidal gravimeters installed in two regions of the USCB, different in terms of mining seismicity. One of the gravimeters was installed in the southern part of the USCB, near the ROW mine in Rybnik. Intensive exploitation of coal seams takes place in this area at a depth of about 1 km. The foci of mining tremors are located at distances from 0 to 3 km from the place of installation of the gravimetric station, i.e. in the near field of seismic events. The second gravimeter records changes in gravity in the northern part of the USCB, in the post-mining area in Katowice, where exploitation has ended. The anthropogenic seismic events recorded by this instrument come from a distance of several to several dozen kilometers - from the area of distant active coal mines, and thus from the distant field of seismic events. The purpose of the article is to analyze the set of seismo-gravity signals coming from mining tremors recorded by gravimeters over a period of almost 14 months, from November 2018 to December 2019 in the aspect of their usefulness for the study of mining induced rock mass movements. Due to their distinctness, observations conducted by tidal gravimeters system can significantly enrich seismological information obtained from traditional mining seismological in a very low frequency range of rock mass motions.

8

Seismicity analysis of selected faults in Makran Southern Pakistan

Khan Muhammad Jahangir, Ali Mubarik, Xu Min, Khan Mehrab

Acta Geophysica

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2020

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Vol. 68, no. 4

965--978

EN

This study was focused on evaluation of seismicity yield of key faults guarding the terrestrial Makran region (Balochistan and Iran) using updated datasets. The Makran onshore region is bounded by paramount strike-slip faults (Chaman fault, Ghazaband fault, Ornach-Nal fault and Minab fault). We have compiled the earthquake’s catalog and performed iterative processes for declustering of independent main shocks, estimation of magnitude completeness and b-values. The main shocks of disastrous earthquakes, e.g., Mw 7.7 Quetta (1935) and Mw 7.7 Awaran (2013), have epicenters along the Ghazaband fault and splay of Chaman fault, respectively. The earthquake source parameters such as moment magnitude, focal depth, focal mechanism, and epicenter location was utilized in mapping and seismicity evaluation of the faults. The focal mechanism solution was derived to determine the fault mechanics in generating the Mw>5.0 events along these faults. This study helped us to compare the seismological profles of each boundary fault and present the seismological information including the characteristics of events on/along fault, estimation of re-occurrence period, corresponding b-value, and hazard potential of the of the key faults. Since our study is based on recent dataset, i.e., inclusion of 2013 Mw 7.7 Awaran earthquake, the estimated results could help in better planning against the earthquake hazard in near-feld cities & coastal towns of southern Pakistan.

9

Koyna earthquakes: a review of the mechanisms of reservoir triggered seismicity and slip tendency analysis of subsurface faults

Das Dip, Mallik Jyotirmoy

Acta Geophysica

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2020

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Vol. 68, no. 4

1097--1112

EN

Koyna region in western India experienced more than 1,00,000 earthquakes of diferent magnitudes (M ~ 1.0–6.3) in the past fve decades. Earthquakes in this region are believed to be triggered by a change in fuid pressure due to the percolation of the reservoir (Koyna and Warna reservoir) water into the subsurface. A drilling program was set up by the Ministry of Earth Sciences, India and International Continental Scientifc Drilling Program (ICDP) to study the deep subsurface lithol ogy, structure, thermal attributes, etc. as the area is covered by~950 m of thick Deccan basalts. This paper reviews all the hypotheses proposed by earlier workers to explain the mechanism of reservoir trigger causing earthquakes and summarizes such theories to a simple generic model. Slip tendency analysis was further carried out based on the proposed model to explain the dependence of fault slip on fault geometry, rock mechanical properties, stress and fuid gradients. Finally, faults at various depths were characterized (favourably oriented, unfavourably oriented and severely misoriented) based on their potential to go into failure.

10

Earthquake source dynamics and kinematics of the Eastern Indian Shield and adjoining regions

Singh Rashmi, Khan Prosanta Kumar, Singh A. P.

Acta Geophysica

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2020

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Vol. 68, no. 2

337--355

EN

The Eastern Indian Shield (EIS) consists of two cratonic nuclei, namely Singhbhum craton and Chhotanagpur Granitic Gneissic terrain. This area contains several crisscross faults, lineaments, shear zones, numerous hot springs and three major rivers (e.g., Ganga, Brahmaputra and Damodar). The area is regionally covered by 7 seismic stations and jointly recorded 16 events from the study area, and less noisy waveforms of 4 events were used for focal mechanism analysis using the Cut and Paste method. The focal parameters of these 4 events were compiled with results of 8 events computed by diferent workers for the study area. To understand the detailed tectonics, focal mechanisms of 21 events for the Himalayan segment were taken from CMT Harvard catalog of duration 1976–2017. Spatial variations of operative stress felds for major tectonic domains were analyzed in the present study based on stress inversion of focal mechanism parameters. We observed strike-slip-dominated movements in the EIS, which changes partially into extension in the northeast part between the Ganga and Brahmaputra Rivers. Thrust-dominated movements evidenced by focal mechanisms and the pure compression in the western segment of the Himalaya in the north might be promoting shear movements in the EIS and adjoining regions. The pure strike-slip in the eastern segment of the Himalaya and its deeper level account for lateral shearing and eastward movements of diferent tectonic blocks. The normal faulting earthquakes in the northeast part might be indicating stretching in the basement because of convergence of Indian lithosphere beneath the Myanmar plate.

11

Comparative analysis of the empirical seismic vulnerability of typical structures in multiple intensity zones

Li S. Q., Yu T. L., Chen Y. S.

Archives of Civil Engineering

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2019

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Vol. 65, nr 3

167--183

EN

To study the difference in seismic vulnerability of multiple typical structures in multiple intensity zones, the seismic damage of 7099 buildings of Dujiangyan masonry structure (MS), reinforced concrete structure (RC) and bottom frame seismic wall masonry (BFM) in the 2008 Wenchuan earthquake in China is summarized and analysed. First, a statistical analysis of the data is carried out, the empirical seismic vulnerability matrix and model curves are established by considering the number of storeys, the age and the fortification factors.The vulnerability curves of the cumulative exceeding probability of the empirical seismic damage and the grade of the seismic damage in multiple intensity zones are shown. The mean damage index vulnerability matrix model is proposed and verified using the empirical seismic damage matrix of typical structures.

12

Statistical properties of complex network for seismicity using depth-incorporated influence radius

He Xuan, Wang Luyang, Zhu Hongbo, Liu Zheng

Acta Geophysica

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2019

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Vol. 67, no. 6

1515--1523

EN

In recent years, seismic time series has been used to construct complex network models in order to describe the seismic complexity. The effect of the factor focal depth has been elided in some of these models. In this paper, we aim to construct a new complex network model for seismicity by considering depth factor from the earthquake catalog and investigate the statistical properties of the network. Since the networks have been proved to be scale-free and small-world properties, the new network models should be studied whether the properties have changed. The results show that the new network model by considering depth factor is still scale-free and small-world. However, it is found that its average degree is smaller than the original network. The clustering coefficient increases at the year including mainshocks. The assortativity coefficient, which demonstrates preferential attachment of nodes, is positive and shows consistent pattern when main shocks occur.

13

Forecasting seismic activity rates in northwest Himalaya through multivariate autoregressive forecast of seismicity algorithm

Chingtham Prasanta, Tiwari Anurag, Yadav Arabind Kumar

Acta Geophysica

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2019

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Vol. 67, no. 2

465--476

EN

In this study, a model based on multivariate autoregressive forecast of seismicity (MARFS) algorithm is adopted to forecast seismic activity rates in northwest Himalaya, using the compiled homogenized moment magnitude (MW) based catalogue. For this purpose, each source zone delineated by Yadav et al. (Pure Appl Geophys 170:283–295, 2012) is divided into a spatial grid interval of 0.5° × 0.5° while the entire catalogue span (1975–2010) is segregated into six time periods/grids to estimate seismic activity rates spatially and temporally. These seismic activity rates which are estimated from spatial density map of hypocenters exhibit high values in Chaman Fault (Zone 1), Hindukush-Pamir region (Zone 3) and the mega thrust systems, i.e., Main Central Thrust, Main Boundary Thrust and Himalayan Frontal Thrust (Zone 4). Then, the seismic activity rates during 2011–2016 could be forecasted by extrapolating (through auto-regression procedure) those observed for previous time periods. The forecast seismic activity rates are estimated within the values of 0 and 7.57 with high values primarily observed in Hindukush-Pamir region of Zone 3 and the gently north-dipping thrust fault systems (Main Central Thrust, Main Boundary Thrust, Himalayan Frontal Thrust) of Zone 4. Finally, the associated area under the curve of receiver operating characteristics graph suggests the superiority of forecasting model with respect to random prediction, whereas results of the data-consistency test, i.e., N test of our model, exhibit consistency in between the observed and simulated likelihoods. Moreover, the hypothetical t test performed in between the spatial grids of forecast seismic activity rates and observed seismic activity rates confirms that the former is consistent with the latter.

14

Study on energy distributions of strong seismic events in the USCB

Bracławska A., Idziak A. F.

Contemporary Trends in Geoscience

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2017

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Vol. 6, iss. 1

41--56

EN

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.

15

Non-extensive statistical physics analysis of earthquake magnitude sequences in North Aegean Trough, Greece

Papadakis G., Vallianatos F.

Acta Geophysica

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2017

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Vol. 65, no. 3

555--563

EN

In a recent study, Papadakis et al. (Physica A 456: 135–144, 2016) investigate seismicity in Greece, using the non-extensive statistical physics formalism. Moreover, these authors examine the spatial distribution of the non-extensive parameter qM and show that for shallow seismicity, increase of qM coincides with strong events. However, their study also reveals low qM values along the North Aegean Trough, despite the presence of strong events during 1976–2009. Consequently, the present study further examines the temporal behaviour of parameters qM and A, to reveal their relation with the evolution of the earthquake sequence. Through temporal examination of these parameters, we aim to show that the seismogenic system of the North Aegean Trough presents high degree of interactions after strong earthquakes during the studied period. Our findings indicate that increase of qM signifies the existence of long-range correlations. If its value does not significantly decrease after a strong earthquake (i.e. M ≥ 5) then the studied area has not reached the state of equilibrium.

16

Earthquake hazard assessment in the zagros orogenic belt of Iran using a fuzzy rule-based model

Farahi Ghasre Aboonasr S., Zamani A., Razavipour F., Boostani R.

Acta Geophysica

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2017

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Vol. 65, no. 4

589--605

EN

Producing accurate seismic hazard map and predicting hazardous areas is necessary for risk mitigation strategies. In this paper, a fuzzy logic inference system is utilized to estimate the earthquake potential and seismic zoning of Zagros Orogenic Belt. In addition to the interpretability, fuzzy predictors can capture both nonlinearity and chaotic behavior of data, where the number of data is limited. In this paper, earthquake pattern in the Zagros has been assessed for the intervals of 10 and 50 years using fuzzy rule-based model. The Molchan statistical procedure has been used to show that our forecasting model is reliable. The earthquake hazard maps for this area reveal some remarkable features that cannot be observed on the conventional maps. Regarding our achievements, some areas in the southern (Bandar Abbas), southwestern (Bandar Kangan) and western (Kermanshah) parts of Iran display high earthquake severity even though they are geographically far apart.

17

A physics-based earthquake simulator and its application to seismic hazard assessment in Calabria (Southern Italy) region

Console R., Nardi A., Carluccio R., Murru M., Falcone G., Parsons T.

Acta Geophysica

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2017

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Vol. 65, no. 1

243--257

EN

The use of a newly developed earthquake simulator has allowed the production of catalogs lasting 100 kyr and containing more than 100,000 events of magnitudes ≥4.5. The model of the fault system upon which we applied the simulator code was obtained from the DISS 3.2.0 database, selecting all the faults that are recognized on the Calabria region, for a total of 22 fault segments. The application of our simulation algorithm provides typical features in time, space and magnitude behavior of the seismicity, which can be compared with those of the real observations. The results of the physics-based simulator algorithm were compared with those obtained by an alternative method using a slip-rate balanced technique. Finally, as an example of a possible use of synthetic catalogs, an attenuation law has been applied to all the events reported in the synthetic catalog for the production of maps showing the exceedance probability of given values of PGA on the territory under investigation.

18

Study of Site Effect at Seismic Station Located in Undermined Area of Karviná Region (Czech Republic)

Lednicka M., Kalab Z.

Acta Geophysica

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2016

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Vol. 64, no. 5

1715--1730

EN

The Karviná region is well known as an area with an intensive mining induced seismicity. The local geological pattern, especially subsurface sedimentary layers, belongs to one of the most important factors that influence the amplification of seismic effect on the surface. In order to investigate the amplification effect, there are used methods of spectral ratio that enable to analyse records of vibrations. In the present study, two methods, signed as SSR (standard spectral ratio) and HVSR (horizontal to vertical spectral ratio), were used for the site effect evaluation. The analysis was performed in the populated Doubrava locality where high seismic loading on the surface due to mining induced seismicity is documented.

19

Preliminary Results of Anthropogenic Seismicity Monitoring in the Region of Song Tranh 2 Reservoir, Central Vietnam

Wiszniowski J., Giang N. V., Plesiewicz B., Lizurek G., Van D. Q., Khoi L. Q., Lasocki S.

Acta Geophysica

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2015

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Vol. 63, no. 3

843--862

EN

Song Tranh 2 hydropower plant and the reservoir containing backed up water are located in the Quang Nam province (Central Vietnam). The region experiences unusual seismic activity related to the reservoir impoundment, with earthquakes of magnitude up to 4.7. In result of cooperation between the Institute of Geophysics, Vietnam Academy of Sciences and Technology and the Institute of Geophysics, Polish Academy of Sciences a seismic network has been built to facilitate seismic monitoring of the Song Tranh 2 area. The network, operating since August 2013, consists of 10 seismic stations. Here we show that the network is sufficient for advanced data processing. The first results of monitoring of the earthquake activity in Song Tranh 2 area in the period between 2012 and 2014, especially the completeness of catalogs, study and comparisons between water level and the seismic activity suggest direct connection between reservoir exploitation and anthropogenic seismicity.

20

Mining Induced Seismic Event on an Inactive Fault

Lizurek G., Rudziński Ł., Plesiewicz B.

Acta Geophysica

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2015

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Vol. 63, no. 1

176--200

EN

On 19 March 2013, a tremor shook the surface of Polkowice town where the Rudna Mine is located. This event, of ML = 4.2, was the third most powerful seismic event recorded in the Legnica Głogów Copper District (LGCD). Inhabitants of the area reported that the felt tremor was bigger and lasted longer than any other ones felt in the last couple of years. Analysis of spectral parameters of the records from in-mine seismic system and surface LUMINEOS network along with broadband station KSP record were carried out. The location of the event was close to the Rudna Główna Fault zone; the nodal planes orientations determined with two different approaches were almost parallel to the strike of the fault. The mechanism solutions were also obtained as Full Moment Tensor from P-wave amplitude pulses of underground records and waveform inversion of surface network seismograms. The results from the seismic analysis along with macroseismic survey and observed effects from the destroyed part of the mining panel indicate that the mechanism of the event was complex rupture initiated as thrust faulting on an inactive tectonic normal fault zone. The results confirm that the fault zones are the areas of higher risk, even in case of carefully taken mining operations