%0 Journal Article
%@ 0033-4553
%A Białoń, Wojciech
%A Lizurek, Grzegorz
%A Dec, Jerzy
%A Cichostępski, Kamil
%A Pietsch, Kaja
%A Institute of Geophysics Polish Academy of SciencesWarsawPoland,
%A Institute of Geophysics Polish Academy of SciencesWarsawPoland,
%A Faculty of Geology, Geophysics and Environmental ProtectionAGH University of Science and TechnologyKrakówPoland,
%A Faculty of Geology, Geophysics and Environmental ProtectionAGH University of Science and TechnologyKrakówPoland,
%A Faculty of Geology, Geophysics and Environmental ProtectionAGH University of Science and TechnologyKrakówPoland,
%D 2019
%F epos:2225
%I Springer Verlag
%J Pure and Applied Geophysics
%K Moment tensor inversion triggered seismicity anthropogenic seismicity probabilistic Bayesian relocation
%T Relocation of Seismic Events and Validation of Moment Tensor Inversion for SENTINELS Local Seismic Network
%U https://episodesplatform.eu/eprints/2225/
%X Seismic activity of Podhale (Poland) and Spiš (Slovakia) regions has been recognized for years. The first information about tremors from this area comes from the XVIII century. Four earthquakes, with intensity over VI in the MSK scale, were reported in 1643, 1724, 1840 and 1901. Since 1960’s an instrumental measurements have been conducted. However, until 2011 no stronger tremors have been recorded in the area of artificial water reservoir Czorsztyn lake located in extremely complex geotechnical condition, between border zone of Inner and Outer Carpathians separated by Pieniny Klippen Belt. Before Czorsztyn 2D seismic survey, knowledge of tectonic boundaries and velocities was very limited. The seismic survey confirmed assumptions of a flower type faults system and provided the first 3D velocity model for this area. After a series of earthquakes, in 2013 a SENTINELS network started its operation and since that time it recorded almost 200 events. The focal mechanisms were calculated for around 20 of them. Both location and moment tensor are crucial in the investigation of the origins of seismogenic process related to industrial operations. Therefore the relocation of the events and validation of the moment tensor solutions for the SENTINELS network were conducted with the use of a 3D velocity model. The validation of mechanisms was conducted with the use of the synthetic tests based on the 1D velocity model derived from the 3D velocity model, taking into account its lateral velocity anisotropy. It was based on the synthetic amplitudes generated with the assumed normal and strike-slip faulting type, similar to the obtained solutions. The validation proved that focal mechanisms are reliable even in a sparse focal coverage and noise not exceeding 40% of the P-wave amplitude. Most of the events are normal or strike-slip with nodal planes striking NW–SE or NNE-SSW. The latter ones are in agreement with the orientation of the main discontinuities in this area.

%0 Journal Article
%@ 1895-6572
%A Cielesta, Szymon
%A Orlecka-Sikora, Beata
%A Staszek, Monika
%A Urban, Pawel
%A Olszewska, Dorota
%A Ruigrok, Elmer
%A Toon, Sam
%A Picozzi, Matteo
%A Kwiatek, Grzegorz
%A Cesca, Simone
%A Lopez-Comino, Jose Angel
%A Isherwood, Catherine
%A Montcoudiol, Nelly
%A Jarosławski, Janusz
%A Institute of Geophysics Polish Academy of SciencesWarsawPoland,
%A Institute of Geophysics Polish Academy of SciencesWarsawPoland,
%A Institute of Geophysics Polish Academy of SciencesWarsawPoland,
%A Institute of Geophysics Polish Academy of SciencesWarsawPoland,
%A Institute of Geophysics Polish Academy of SciencesWarsawPoland,
%A KNMI - Royal Netherlands Meteorological InstituteDe BiltThe Netherlands,
%A Keele UniversityKeeleUK,
%A Università degli Studi di Napoli Federico II NaplesItaly, AMRA S.c. a r.l.NaplesItaly,
%A Helmholtz-Zentrum Potsdam Deutsches GeoForschungs Zentrum GFZPotsdamGermany,
%A Helmholtz-Zentrum Potsdam Deutsches GeoForschungs Zentrum GFZPotsdamGermany,
%A Helmholtz-Zentrum Potsdam Deutsches GeoForschungs Zentrum GFZPotsdamGermany,
%A RSKW Ltd.StirlingUK,
%A University of GlasgowGlasgowUK,
%A Institute of Geophysics Polish Academy of SciencesWarsawPoland,
%D 2019
%F epos:2206
%I Versita, Warsaw and Springer-Verlag Berlin Heidelberg
%J Acta Geophysica
%K SHEER Smart database Multidisciplinary data Integration TCS platform
%N 1
%P 291-297
%T SHEER “smart” database: technical note
%U https://episodesplatform.eu/eprints/2206/
%V 67
%X The SHEER database brings together a large amount of data of various types: interdisciplinary site data from seven independent episodes, research data and those for the project results dissemination process. This concerns mainly shale gas exploitation test sites, processing procedures, results of data interpretation and recommendations. The smart SHEER database harmonizes data from different fields (geophysical, geochemical, geological, technological, etc.), creates and provides access to an advanced database of case studies of environmental impact indicators associated with shale gas exploitation and exploration, which previously did not exist. A unique component of the SHEER database comes from the monitoring activity performed during the project in one active shale gas exploration and exploitation site at Wysin, Poland, which started from the pre-operational phase. The SHEER database is capable of the adoption of new data such as results of other Work Packages and has developed an over-arching structure for higher-level integration.

%0 Journal Article
%@ 23003960
%A Czarny, Rafał
%A Pilecki, Zenon
%A Drzewińska, Dorota
%A The Mineral and Energy Economy Research Institute of the Polish Academy of Sciences,,
%A The Mineral and Energy Economy Research Institute of the Polish Academy of Sciences,,
%A AGH University of Science and Technology,,
%D 2018
%F epos:2145
%I Elsevier
%J Journal of Sustainable Mining
%T The application of seismic interferometry for estimating a 1D S-wave velocity model with the use of mining induced seismicity
%U https://episodesplatform.eu/eprints/2145/
%X The main objective of this paper is to present the usefulness of the seismic interferometry method to determine the S-wave velocity model of the rock mass affected by exploitation in the KGHM Rudna copper ore mine. The research aim was achieved on the basis of seismic data, acquired from seismograms, of 10 strong seismic events of magnitude greater than 2.6. They were recorded by a pair of seismometers deployed on mining terrain. In the first stage, the Rayleigh wave between seismometers was estimated. Then, the group velocity dispersion curves of fundamental and first higher modes were identified. Finally, inversion of the dispersion curves to a 1D S-wave velocity model up to 500 m in depth was obtained. The velocity model was determined for the part of the rock mass partially affected by mining. The results confirm similar rock mass structure and velocities of the subsurface layers as those obtained by the archival 3D model. In both models, a high degree of correlation in the boundary location between the overburden of the Cenozoic formations and the bedrock of the Triassic formations was observed. The applied methodology can be used to estimate the S-wave velocity model in other mining regions characterized by strong seismicity.

%0 Journal Article
%@ 2296-6463
%A Garcia, Alexander
%A Faenza, Licia
%A Morelli, Andrea
%A Antoncecchi, Ilaria
%A Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Bologna, Italy,
%A Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Nazionale Terremoti, Bologna, Italyv,
%A Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Bologna, Italy,
%A Ministero dello Sviluppo Economico, Direzione Generale per le Infrastrutture e la Sicurezza dei Sistemi Energetici e Geominerari (DGISSEG), Rome, Italy,Ricerca sul Sistema Energetico S.p.A (RSE), Milano, Italy,
%D 2021
%F epos:2318
%I Frontiers Media
%J Frontiers in Earth Science
%T Can Hydrocarbon Extraction From the Crust Enhance or Inhibit Seismicity in Tectonically Active Regions? A Statistical Study in Italy
%U https://episodesplatform.eu/eprints/2318/
%V 9
%X A number of oil- and gas-producing leases have been operating in Italy in the last decades, many of which are located in the surroundings of tectonically active regions. Identifying human-induced seismicity in areas with high levels of natural seismicity is a difficult task for which virtually any result can be a source of controversy. We implemented a large-scale analysis aiming at tracking significant departures of background seismicity from a stationary behavior around active oil and gas development leases in Italy. We analyzed seismicity rates before and after hydrocarbon peak production in six oil-producing and 43 gas-producing leases, and evaluate the significance of possible seismicity rate changes. In a considerable number of cases seismicity rate results stationary. None of the observed cases of seismicity rate increase after the peak production is statistically significant (at a s.l. = 0.05). Conversely, considering cases of seismicity rate decrease after peak production, our results suggest that the seismicity rate reduction is statistically significant (s.l. = 0.05) around one oil-producing lease (Val d’Agri, Basilicata) and around a cluster of gas-producing leases in Sicily. Our results put in evidence correlated changes between the rates of shallow seismicity and hydrocarbon production in these areas, which are then identified as hotspots requiring more detailed research; assessing actual causal relationships between these processes will require further physically-based modelling. If a physical causative link between these processes exists, then the observed seismicity rate reduction could either be due to increased seismicity during the progressive increase in production before reaching its maximum, or to an actual seismicity rate reduction after that peak. Considering that there is evidence of seismicity occurring before the start of hydrocarbon production, which contrasts with the evident reduction of events observed after the peak production, we think it likely that the seismicity inhibition is a plausible hypothesis. Using a simple model we also calculate Coulomb stress changes in planes optimally oriented for failure, and we show that under some conditions the inhibition of seismicity is feasible in at least one of these cases. We conclude that more efforts to study the mechanisms and the possible consequences of anthropogenically-driven seismicity inhibition are required.

%0 Journal Article
%@ 0956-540X
%A Garcia-Aristizabal, Alexander
%A Istituto Nazionale di Geofisica e Vulcanologia,
%D 2018
%F epos:2124
%I Oxford University Press
%J Geophysical Journal International
%K Probabilistic forecasting; Induced seismicity; Statistical Seismology
%N 1
%P 471-493
%T Modelling fluid-induced seismicity rates associated with fluid injections: examples related to fracture stimulations in geothermal areas
%U https://episodesplatform.eu/eprints/2124/
%V 215
%X In this paper, we present a model for describing relationships between fluid-induced seismic-  ity and operational parameters of fluid injections. Considering seismic sequences occurring  during sustained fluid injections, we present a novel covariate approach in which a probability  distribution is defined as a basic template function for modelling the interevent times (i.e.  the time intervals between consecutive events), and the possible dependencies on operational  parameters are modelled writing the parameters of the probabilistic model in terms of deter-  ministic functions of explanatory covariates that are selected from the operational data. The  implemented model is tested using data from two cases of reservoir stimulations in geother-  mal systems (The Geysers, US and Cooper Basin, Australia). We have found that a template  exponential distribution of interevent times, with a linear function relating the logarithm of  the distribution’s  μ  parameter and the logarithm of the injection rate, is the model that better  describes the observations in all the analysed cases. This result suggests that the  μ  parameter  and the injection rate have a power-law relationship. The value of the power-law exponent,  α  1  ,  is an indicator of the relative change in the seismicity rate associated with a relative change  in the injection rate, and it results particularly important for understanding the behaviour of  seismicity at high injection rates.  α  1  =−  1 indicates the special case of a linear relationship  between seismicity rate and injection rate (which usually is the model assumed in the litera-  ture); conversely,  α  1  >  −  1(  α  1  <  −  1) indicates that the relative change in the seismicity rate  associated with a relative change in the injection rate is lower (higher) than the relative change  expected by assuming a linear relationship between these two parameters. Regarding the cases  analysed in this paper, the exponent of the power law varies between  −  1.04 and  −  0.78 in The  Geysers, and between  −  1.22 and  −  0.73 in Cooper Basin. While no clear temporal trends are  observable in the  α  1  values obtained for The Geysers, in Cooper Basin  α  1  increased as the  stimulation tests proceeded (from an initial value of  α  1  =−  1.22 calculated for the first fracture  initiation test to  α  1  =−  0.73 associated with the third fracture initiation test). This behaviour  can be a consequence of the so-called Kaiser effect indicating that, to trigger events, the pore  pressure during new injections must exceed the values already reached in previous injection  operations. Finally, we also studied the gradual decline of seismicity rates in the post-injection  phases in Cooper Basin using the modified Omori law. We explored this data set for looking,  in particular, if there exists a pattern between the parameters controlling the post-injection  seismicity decay rate and the characteristics of the precedent fluid injection.

%0 Journal Article
%@ 1895-6572
%A Garcia-Aristizabal, Alexander
%A Kocot, Joanna
%A Russo, Raffaella
%A Gasparini, Paolo
%A Istituto Nazionale di Geofisica e Vulcanologia Sezione di Bologna Bologna Italy, Center for the Analysis and Monitoring of Environmental Risks (AMRA)Naples Italy,
%A Academic Computer Centre Cyfronet AGH University of Science and TechnologyKrakówPoland,
%A Center for the Analysis and Monitoring of Environmental Risks (AMRA)NaplesItaly,
%A Center for the Analysis and Monitoring of Environmental Risks (AMRA)NaplesItaly,
%D 2019
%F epos:2210
%I Versita, Warsaw and Springer-Verlag Berlin Heidelberg
%J Acta Geophysica
%K Multi-hazard risk assessment Anthropogenic hazards Bow-tie approach Monte Carlo simulations
%N 1
%P 385-410
%T A probabilistic tool for multi-hazard risk analysis using a bow-tie approach: application to environmental risk assessments for geo-resource development projects
%U https://episodesplatform.eu/eprints/2210/
%V 67
%X In this paper, we present a methodology and a computational tool for performing environmental risk assessments for geo-resource development projects. The main scope is to implement a quantitative model for performing highly specialised multi-hazard risk assessments in which risk pathway scenarios are structured using a bow-tie approach, which implies the integrated analysis of fault trees and event trees. Such a model needs to be defined in the interface between a natural/built/social environment and a geo-resource development activity perturbing it. The methodology presented in this paper is suitable for performing dynamic environmental risk assessments using state-of-the-art knowledge and is characterised by: (1) the bow-tie structure coupled with a wide range of probabilistic models flexible enough to consider different typologies of phenomena; (2) the Bayesian implementation for data assimilation; (3) the handling and propagation of modelling uncertainties; and (4) the possibility of integrating data derived form integrated assessment modelling. Beyond the stochastic models usually considered for reliability analyses, we discuss the integration of physical reliability models particularly relevant for considering the effects of external hazards and/or the interactions between industrial activities and the response of the environment in which such activities are performed. The performance of the proposed methodology is illustrated using a case study focused on the assessment of groundwater pollution scenarios associated with the management of flowback fluids after hydraulically fracturing a geologic formation. The results of the multi-hazard risk assessment are summarised using a risk matrix in which the quantitative assessments (likelihood and consequences) of the different risk pathway scenarios considered in the analysis can be compared. Finally, we introduce an open-access, web-based, service called MERGER, which constitutes a functional tool able to quantitatively evaluate risk scenarios using a bow-tie approach.

%0 Journal Article
%A Grasso, Jean-Robert
%A ISterre, Observatoire de Grenoble, Université de Grenoble Alpes,  France,
%D 2017
%F epos:2044
%I EPOS
%J The EPOS Newsletter
%N 4
%T "Sismo-Dance" Workshop-Performance
%U https://episodesplatform.eu/eprints/2044/
%V 4

%0 Journal Article
%@ 0037-1106
%A Grasso, Jean-Robert
%A Karimov, A.
%A Amorese, Daniel
%A Sue, C.
%A Voisin, C.
%A Université de Grenoble‐Alpes, ISTerre,,
%A Université de Grenoble‐Alpes, ISTerre,,
%A Observatoire Volcanologique et Sismologique de Guadeloupe, Institut de Physique du Globe de Paris, Department of Biology and Earth Sciences, Université de Caen‐Normandie,
%A UBFC/CNRS‐UMR Chrono‐environnement, 16 route de Gray,,
%A Université de Grenoble‐Alpes, ISTerre,,
%D 2018
%F epos:2154
%I Seismological Society of America
%J Bulletin of the Seismological Society of America
%N 5B
%P 2967-2982
%T Patterns of Reservoir‐Triggered Seismicity in a Low‐Seismicity Region of France
%U https://episodesplatform.eu/eprints/2154/
%V 108
%X We analyzed the impact of the 26 largest impounded reservoirs on reservoir‐triggered seismicity (RTS) patterns in the low‐seismicity region of continental France. We treat reservoir‐triggered earthquakes as tectonic earthquakes and apply similar concepts in our analysis. Generally, the spatial extent of an aftershock zone is controlled by the mainshock rupture length. In a similar manner, we use reservoir length as an equivalent length to the rupture length to assess the spatial extent of reservoir‐triggering earthquakes and one to three reservoir lengths as a proxy for the near‐field distance where the stress change induced by reservoir impoundment may trigger seismicity. Accordingly, we define the  1Lr  distance as the near‐field reservoir effect on seismicity and the  10Lr  distance as the far field, null effect of reservoir stress change on background seismicity. We find that (1) about a quarter of the reservoirs trigger  Mmax=2.5–4.7  within the  1Lr  distance in a 15 yr space time window, and (2) as tested against a randomized series, superposed epoch analysis demonstrates a robust increase in the average seismicity rate within 2 yrs for the  1–3Lr  distance from reservoirs. The reservoirs that trigger in the (⁠ 1Lr ⁠) near‐field distance are significantly larger than the nontriggering ones. While considering the distance of triggering of earthquakes from the reservoir, it is more appropriate to consider the normalized distance (the distance normalized by the reservoir length) to identify earthquake triggering reservoirs at a  1Lr  distance. While considering reservoir dimensions, the reservoir length appears to be a more important parameter than the reservoir depth, as the length is proportional to the area of significant stress change. Our results suggest that the RTS mimics the aftershock sequence of a slow reservoir‐impoundment loading, with a corresponding  M∗reservoir=M(Lr)  mainshock magnitude. Further, when considering mainshock–aftershock interactions, our analysis and observations support that the  Mmax  for RTS for a given reservoir remains, on average, smaller than the reservoir magnitude equivalent.

%0 Journal Article
%@ 1895-6572
%A Gunning, Andrew
%A Lasocki, Stanislaw
%A Capuano, Paolo
%A RSKW LtdStirlingUK,
%A Institute of GeophysicsPolish Academy of SciencesWarsawPoland,
%A Dipartimento di Fisica, E. R. CaianielloUniversità degli Studi di SalernoFiscianoItaly,
%D 2019
%F epos:2204
%J Acta Geophysica
%K Shale Long-term monitoring Risk SHEER Hydraulic fracturing
%N 1
%P 279-290
%T Assessing environmental footprints induced by geo-energy exploitation: the shale gas case
%U https://episodesplatform.eu/eprints/2204/
%V 67
%X This Special Issue describes the main outcomes from the SHEER (SHale gas Exploration and Exploitation induced Risks) project, a 3 year EC Horizon 2020 funded investigation into environmental risk associated with shale oil and gas development within the European Union. A key feature of the programme of work has been the independent monitoring of a shale gas well at Wysin, Poland, through a network of seismic, groundwater and air quality measurement arrays and shallow borehole sensors both in advance of and subsequent to hydraulic fracturing operations. In conjunction with the environmental monitoring programme, a multi-hazard risk assessment technique has been applied to shale gas operations to identify and assess the likelihood of occurrence of incidents and their potential impacts on the surrounding environment. Given the limited development of shale oil and gas in Europe experience out-with the European Union, particularly in the USA and Canada, has been integrated into the project. A further element of the research has been the dissemination of results through academic publications, a large number of presentations to conferences and at SHEER events in Italy, Poland and the UK. This introductory paper provides a brief synopsis of the research and development that has been carried out, with a primary focus on the best practice recommendations, policy guidelines and key learning that have been developed during the course of the project. Policy guidelines include issues of relevance to regulators and government in providing effective regulatory oversight of shale gas operations within the European Union. Recommendations for best practice are primarily related to the monitoring and evaluation of environmental risk in the development of shale gas within the European Union.

%0 Journal Article
%@ 2072-4292
%A Ilieva, Maya
%A Rudzinski, Lukasz
%A Pawłuszek-Filipiak, Kamila
%A Lizurek, Grzegorz
%A Kudłacik, Iwona
%A Tondaś, Damian
%A Olszewska, Dorota
%A Institute of Geodesy and Geoinformatics, Wrocław University of Environmental Life and Sciences, 50-357 Wrocław, Poland,
%A Institute of Geophysics, Polish Academy of Sciences, 01-452 Warszawa, Poland,
%A Institute of Geodesy and Geoinformatics, Wrocław University of Environmental Life and Sciences, 50-357 Wrocław, Poland,
%A Institute of Geophysics, Polish Academy of Sciences, 01-452 Warszawa, Poland,
%A Institute of Geodesy and Geoinformatics, Wrocław University of Environmental Life and Sciences, 50-357 Wrocław, Poland,
%A Institute of Geodesy and Geoinformatics, Wrocław University of Environmental Life and Sciences, 50-357 Wrocław, Poland,
%A Institute of Geophysics, Polish Academy of Sciences, 01-452 Warszawa, Poland,
%D 2020
%F epos:2263
%I MDPI
%J Remote Sensing
%N 10
%P 1570
%T Combined Study of a Significant Mine Collapse Based on Seismological and Geodetic Data—29 January 2019, Rudna Mine, Poland
%U https://episodesplatform.eu/eprints/2263/
%V 12
%X On 29 January 2019, the collapse of a mine roof resulted in a significant surface deformation and generated a tremor with a magnitude of 4.6 in Rudna Mine, Poland. This study combines the seismological and geodetic monitoring of the event. Data from local and regional seismological networks were used to estimate the mechanism of the source and the ground motion caused by the earthquake. Global Navigation Satellite System data, collected at 10 Hz, and processed as a long-term time-series of daily coordinates solutions and short-term high-frequency oscillations, are in good agreement with the seismological outputs, having detected several more tremors. The range and dynamics of the deformed surface area were monitored using satellite radar techniques for slow and fast motion detection. The radar data revealed that a 2-km2 area was affected in the six days after the collapse and that there was an increase in the post-event rate of subsidence.

%0 Journal Article
%@ 0956-540X
%A Kokowski, Jakub
%A Rudziński, Łukasz
%A Department of Seismology, Institute of Geophysics PAS,
%A Department of Seismology, Institute of Geophysics PAS,
%D 2023
%F epos:2425
%J Geophysical Journal International
%K Spatial analysis, Computational seismology, Earthquake monitoring and test-ban treaty verification, Induced seismicity
%N 2
%P 839-851
%T Estimation of location errors for local seismic network in an area with intense and weak seismicity
%U https://episodesplatform.eu/eprints/2425/
%V 234
%X We have modified a method for estimation of location errors distribution for local seismic networks in area with intense shallow seismicity. We have used the variance-covariance matrices in a regular grid of points. The traveltime residuals variance is calculated as a function of source–receiver distance, while the new idea is to estimate the detection range of seismic stations on the basis of the probability of detection plots. In consequence, the method enables the evaluation of the applied velocity models during the analysis of traveltime residuals, as well as evaluation of the usefulness of individual stations with the use of probability plots. Ultimately, it provides assessment of the station configuration by analysing the distribution of location errors. The data needed for the analysis are a seismic catalogue containing earthquakes locations together with traveltime residuals and the velocity model, as well as stations metadata. The method is tested on using the real data which come from the LUMINEOS local seismic network, the network used for induced seismicity monitoring in the Legnica–Głogow Copper District in Poland.

%0 Journal Article
%@ 1365-1609
%A Kozlowska, Maria
%A Orlecka-Sikora, Beata
%A Rudzinski, Lukasz
%A Cielesta, Szymon
%A Mutke, Grzegorz
%A Institute of Geophysics, Polish Academy of Sciences, Warszawa, Poland,
%A Institute of Geophysics, Polish Academy of Sciences, Warszawa, Poland,
%A Institute of Geophysics, Polish Academy of Sciences, Warszawa, Poland,
%A Institute of Geophysics, Polish Academy of Sciences, Warszawa, Poland,
%A Central Mining Institute, Katowice, Poland,
%D 2016
%F epos:1799
%I Elsevier Science
%J International Journal of Rock Mechanics and Mining Sciences
%K Mining induced seismicity; Coulomb stress transfer; Tectonic stress
%P 5-15
%T Atypical evolution of seismicity patterns resulting from the coupled natural, human-induced and coseismic stresses in a longwall coal mining environment
%U https://episodesplatform.eu/eprints/1799/
%V 86
%X A very unusual time-space distribution of seismicity accompanying coal exploitation has been observed in a Polish mine. The earthquakes did not follow the depth of mining but exhibited changing depths from far below to close to the mined seam. One of the deep events which occurred at close epicentral distance to the active mining front was ML3.7 event. This paper presents the study of possible coupling of natural, human-induced and coseismic stresses in a longwall coal mining environment. The full moment tensor solution showed that the strong earthquake occurred on an almost vertical plane consistent with approximate strike of local tectonic structure. The signal correlation analysis revealed some highly correlated pairs within both deep and shallow event groups. To evaluate inducing factor of ongoing and past exploitation, geomechanical modelling of its influence on strain and stress at the target depth has been performed. The results exhibited a changing vertical stress regime, which might have promoted failure on preexisting, almost vertical planes of weakness. The earthquakes' rate variation in time showed no increase in activity right after the occurrence of ML3.7 event. The P-S-wave spectra corner frequency ratio had an average of 1.0, suggesting slow rupture. However, the Coulomb stress change analysis showed that the magnitude of stress changes due to coseismic slip of ML3.7 event at the hypocentral depth is of the same order as the stress changes caused by mining. Thus, the distribution of seismicity at this level could have been driven by both exploitation and coseismic stresses. Moreover, the seismicity which occurred within first few weeks after ML3.7 event, followed positive stress changes. All the obtained results let us prove that the ML3.7 event was a tectonic earthquake triggered by ongoing exploitation and that the distribution of following seismicity was affected by coupled natural, exploitation-induced and coseismic stresses.

%0 Journal Article
%@ 0956-540X
%A Kozłowska, Maria
%A Jamroz, Mateusz
%A Olszewska, Dorota
%A Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland,
%A Central Mining Institute, Katowice, Poland,
%A Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland,
%D 2021
%F epos:2316
%I Oxford University Press
%J Geophysical Journal International
%K Earthquake ground motions, Earthquake hazards, Induced seismicity
%N 2
%P 1258-1270
%T On the aftershock productivity in mining-induced seismicity—insight into seismicity of Rudna copper ore mine, Poland
%U https://episodesplatform.eu/eprints/2316/
%V 225
%X Mining-induced seismic events can be followed by aftershocks that increase the risk associated with the exploitation. The understanding of the aftershock generation process in induced seismicity may improve post-earthquake safety procedures applied in mines. Rudna copper ore mine in southwestern Poland commonly experiences intense and strong seismic activity accompanying the room-and-pillar exploitation of copper ore. Some strong (magnitude >2) mining events are followed by numerous aftershocks and some are not followed by any. In this study, we seek to find whether there is any geological, technological or seismological cause of this diversity. We study 46 strong mining events and focus on their aftershock productivity. We analyse the geological and mining setting of the studied events, their signal similarity, stress drops and the ground motion effect using data from three different seismic networks. Our results show that seismic events producing large aftershock sequences may share similar focal mechanisms and have larger ground effects than events with no aftershocks. The results also indicate the potential differences in stress drops. This interesting observation may help to better evaluate the aftershock hazard in mines. It also indicates the need for a more detailed analysis of the focal mechanisms of strong events and their relationship to the exploitation technique.

%0 Journal Article
%@ 0263-2241
%A Kudłacik, Iwona
%A Kapłon, Jan
%A Lizurek, Grzegorz
%A Crespi, Mattia
%A Kurpiński, Grzegorz
%A Institute of Geodesy and Geoinformatics, Wrocław University of Environmental and Life Sciences,,
%A Institute of Geodesy and Geoinformatics, Wrocław University of Environmental and Life Sciences,,
%A Institute of Geophysics, Polish Academy of Sciences,,
%A Geodesy and Geomatics Division, DICEA-Sapienza University of Rome,,
%A KGHM CUPRUM Sp. z.o.o. – Research and Development Centre,
%D 2020
%F epos:2284
%I Elsevier Science
%J Measurement
%K high-rate GNSS, GNSS-seismology, mining tremor
%P 108396
%T High-rate GPS positioning for tracing anthropogenic seismic activity: the 29 January 2019 mining tremor in Legnica- Głogów Copper District, Poland
%U https://episodesplatform.eu/eprints/2284/
%V 168
%X High-rate GNSS observations are usually studied in relation to earthquake analysis and structural monitoring. Most of the previous research on short-term dynamic deformations has been limited to natural earthquakes with magnitudes exceeding 5 and amplitudes equal to several dozen centimetres. High-frequency position monitoring via GNSS stations is particularly important in mining areas due to the need to monitor mining damages. On 29 January 2019 (12:53:44 UTC), an M3.7 event occurred in the area of Legnica-Głogów Copper District.    This study presents GPS-derived displacement analysis in relation to seismological data. Station position time series were determined by double differencing and Precise Point Positioning. The peak ground displacement was 2–14 millimetres. The correlation coefficients between GPS and seismological displacement time series reached 0.92. A statistical evaluation of GPS displacement time series was carried out to detect an event using only GPS observations.

%0 Journal Article
%@ 0094-8276
%A Lasocki, Stanislaw
%A Orlecka-Sikora, Beata
%A Institute of Geophysics Polish Academy of SciencesWarsawPoland,
%A Institute of Geophysics Polish Academy of SciencesWarsawPoland,
%D 2020
%F epos:2246
%I American Geophysical Union
%J Geophysical Research Letters
%T High injection rates counteract formation of far-reaching fluid migration pathways at The Geysers geothermal field
%U https://episodesplatform.eu/eprints/2246/
%X Deep underground water injections induce seismicity. When the seismic fractures coalesce into far-reaching pathways for fluid migration, the migrating fluid may reach pre-existing faults, and by decreasing fault strength, can trigger major seismic events. We assume that the potential for building such pathways depends on closeness of hypocenters, similarity of fracture planes orientations, and closeness of radii taking off from the injection point, on which events locate. We define this potential as the average distance between seismic events in the space of parameters quantifying the above conditions. We show that in the studied case from The Geysers geothermal field, this potential is highly correlated with injection rate. When the overall level of injection rate is high, the higher the injection rate, the more the potential for building far-reaching pathways for fluid migration is reduced.

%0 Journal Article
%A Lasocki, Stanislaw
%A Orlecka-Sikora, Beata
%D 2016
%F epos:2041
%I EPOS
%J The EPOS Newsletter
%N 03
%P 1-5
%T Integrated approach to geophysical hazards induced by exploration and exploitation of georesources - to facilitate the way of attaining excellence
%U https://episodesplatform.eu/eprints/2041/
%V 01
%X The increased need for energy and minerals requires a variety of complex industrial processes to be performed under more and more difficult environmental conditions. The problem of hazards induced by exploration and exploitation of georesources focuses growing interest by science, industry, public administration, NGO-s and general public. This is especially true in the densely populated Europe, where such technological activities take place close to inhabited and other protected areas. Anthropogenic seismicity, i.e. the undesired dynamic rockmass response to georesources exploitation, is one of the examples of unwanted by-products of technological occupation of humans. It becomes a real problem in areas previously known as aseismic and in association with quite diverse technological processes. The induced earthquakes accompany underground and open-pit mining, both conventional as well as unconventional hydrocarbon exploitation, impoundment of surface reservoirs of liquids, geothermal energy production, underground fluid and gas storage and many other technological processes that perturb the boundary conditions in the affected rockmass. The socio-economic impact of the induced seismicity is very significant. Induced earthquakes can cause material loss, injuries and even fatalities. ...

%0 Journal Article
%@ 0956-540X
%A Leptokaropoulos, Konstantinos Michail
%A Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland,
%D 2020
%F epos:2261
%I Oxford University Press
%J Geophysical Journal International
%K Hydrothermal systems; Probability distributions; Induced seismicity; Statistical  seismology
%N 2
%P 893-906
%T Magnitude distribution complexity and variation at The Geysers geothermal field
%U https://episodesplatform.eu/eprints/2261/
%V 222
%X Earthquake magnitude (size) distribution is a major component required for seismic hazard  assessment and therefore, the accurate determination of its functional shape and variation  is a task of utmost importance. Although often considered as stationary, the magnitude distribution at particular sites may significantly vary over time and space. In this study, the  well-known Gutenberg–Richter (GR) law, which is widely assumed to describe earthquake  magnitude distribution, is tested for a case study of seismicity induced by fluid injection at  The Geysers (CA, USA) geothermal field. Statistical tests are developed and applied in order  to characterize the magnitude distribution of a high quality catalogue comprising seismicity  directly associated with two injection wells, at the north western part of The Geysers. The  events size distribution variation is investigated with respect to spatial, temporal, fluid injection  and magnitude cut-off criteria. A thorough spatio-temporal analysis is performed for defining  seismicity Clusters demonstrating characteristic magnitude distributions which significantly  differ from the ones of the nearby Clusters. The magnitude distributions of the entire seismic  population as well as of the individual Clusters are tested for their complexity in terms of  exponentiality, multimodal and multibump structure. Then, the Clusters identified are further  processed and their characteristics are determined in connection to injection rate fluctuations.  The results of the analysis clearly indicate that the entire magnitude distribution is definitely  complex and non-exponential, whereas subsequent periods demonstrating significantly diverse  magnitude distributions are identified. The regional seismicity population is divided into three  major families, for one of which exponentiality of magnitude distribution is clearly rejected,  whereas for the other two the GR law b-value is directly proportional to fluid injection. In  addition, the b-values of these Families seem to be significantly magnitude dependent, a fact  that is of major importance for seismic hazard assessment implementations. To conclude, it  is strongly suggested that magnitude exponentiality must be tested before proceeding to any  b-value calculations, particularly in anthropogenic seismicity cases where complex and time  changeable processes take place.

%0 Journal Article
%@ 0956-540X
%A Leptokaropoulos, Konstantinos Michail
%A Adamaki, Aggeliki K.
%A Roberts, John
%A Gkarlaouni, Charikleia
%A Paradisopoulou, P M
%A Seismology and Physics of the Earth's Interior, Institute of Geophysics, Polish Academy of Sciences, Ks. Janusza 64, 01–452 Warsaw, Poland,
%A Department of Earth Sciences, Uppsala University, Villavagen 16, 752 36 Uppsala, Sweden,
%A Department of Earth Sciences, Uppsala University, Villavagen 16, 752 36 Uppsala, Sweden,
%A Department of Geophysics, School of Geology, Aristotle University of Thessaloniki, GR54124 Thessaloniki, Greece,
%A Department of Geophysics, School of Geology, Aristotle University of Thessaloniki, GR54124 Thessaloniki, Greece,
%D 2018
%F epos:2057
%I Oxford University Press
%J Geophysical Journal International
%K Numerical approximations and analysis, Statistical methods, Statistical seismology
%N 2
%P 940-951
%T Impact of magnitude uncertainties on seismic catalogue properties
%U https://episodesplatform.eu/eprints/2057/
%V 213
%X Catalogue based studies are of central importance in seismological research, to investigate the temporal, spatial and size distribution of earthquakes in specified study areas. Methods for estimating the fundamental catalogue parameters like the Gutenberg-Richter (G-R) b-value and the completeness magnitude (Mc) are well established and routinely applied. However, the magnitudes reported in seismicity catalogues contain measurement uncertainties which may significantly distort the estimation of the derived parameters. In this study, we use numerical simulations of synthetic data sets to assess the reliability of different methods for determining b-value and Mc, assuming the G-R law validity. After contaminating the synthetic catalogues with Gaussian noise (with selected standard deviations), the analysis is performed for numerous data sets of different sample size (N). The noise introduced to the data generally leads to a systematic overestimation of magnitudes close to and above Mc. This fact causes an increase of the average number of events above Mc, which in turn leads to an apparent decrease of the b-value. This may result to a significant overestimation of seismicity rate even well above the actual completeness level. The b-value can in general be reliably estimated even for relatively small data sets (N < 1000) when only magnitudes higher than the actual completeness level are used. Nevertheless, a correction of the total number of events belonging in each magnitude class (i.e. 0.1 unit) should be considered, to deal with the magnitude uncertainty effect. Because magnitude uncertainties (here with the form of Gaussian noise) are inevitable in all instrumental catalogues, this finding is fundamental for seismicity rate and seismic hazard assessment analyses. Also important is that for some data analyses significant bias cannot necessarily be avoided by choosing a high Mc value for analysis. In such cases there may be a risk of severe miscalculation of seismicity rate regardless the selected magnitude threshold, unless possible bias is properly assessed.

%0 Journal Article
%@ 1895-6572
%A Leptokaropoulos, Konstantinos Michail
%A Cielesta, Szymon
%A Staszek, Monika
%A Olszewska, Dorota
%A Lizurek, Grzegorz
%A Kocot, Joanna
%A Lasocki, Stanislaw
%A Orlecka-Sikora, Beata
%A Sterzel, Mariusz
%A Szepieniec, Tomasz
%A Instytut Geofizyki Polskiej Akademii Nauk, Warsaw, Poland,
%A Instytut Geofizyki Polskiej Akademii Nauk, Warsaw, Poland,
%A Instytut Geofizyki Polskiej Akademii Nauk, Warsaw, Poland,
%A Instytut Geofizyki Polskiej Akademii Nauk, Warsaw, Poland,
%A Instytut Geofizyki Polskiej Akademii Nauk, Warsaw, Poland,
%A Akademickie Centrum Komputerowe (ACK)-CyfronetKrakówPoland,
%A Instytut Geofizyki Polskiej Akademii Nauk, Warsaw, Poland,
%A Instytut Geofizyki Polskiej Akademii Nauk, Warsaw, Poland,
%A Akademickie Centrum Komputerowe (ACK)-CyfronetKrakówPoland,
%D 2019
%F epos:2143
%I Springer Verlag
%J Acta Geophysica
%K IS-EPOS platform Anthropogenic, seismicity, E-platform EPOS, Multidisciplinary data
%N 1
%P 299-310
%T IS-EPOS: a platform for anthropogenic seismicity research
%U https://episodesplatform.eu/eprints/2143/
%V 67
%X Research in the field of anthropogenic seismicity (AS) requires not only seismicity data but also data regarding the progress of the technological/production activities which is the origin of the induced or triggered seismic events. Such data are typically restricted and proprietary, and therefore, usually not available for independent researchers who wish to develop, perform and verify scientific research. The induced seismicity-European plate observing system (IS-EPOS) web portal offers to its user’s access to data, applications and documents in order to facilitate AS research. IS-EPOS web portal has been designed to serve as one of the main pillars of the Thematic Core Service—-Anthropogenic Hazards belonging to pan-European multidisciplinary research infrastructure created within the EPOS program. IS-EPOS platform is open for research community and general public according to its rules of access. The platform is operating since January 2016 and is now integrated in the EPOS Integrated Core Services. IS-EPOS e-platform promotes new opportunities to study and comprehend the dynamic and complex solid earth system by integrating the use of multidisciplinary data, data products, analysis models and online applications. The integration of existing and new national and transnational Research Infrastructures increases the access and use of multidisciplinary data recorded by the solid earth observing systems, acquired in laboratory experiments and/or produced by computational simulations. In this paper, we describe the structure and the main innovative characteristics implemented in IS-EPOS. The platform is open to accommodate data integrated within other research projects, and it is continuously being updated with improvements in existing features and implementations of new ones. An appendix at the end of the article provides a summary of acronyms and abbreviations in order to make the reader familiar with the terms used throughout the manuscript.

%0 Journal Article
%@ 0895-0695
%A Leptokaropoulos, Konstantinos Michail
%A Lasocki, Stanislaw
%A Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland,
%A Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland,
%D 2020
%F epos:2259
%I Seismological Society of America
%J Seismological Research Letters
%T SHAPE: A MATLAB Software Package for Time-Dependent Seismic Hazard Analysis
%U https://episodesplatform.eu/eprints/2259/
%X Many seismic processes, in particular, those induced by technological activities for exploitation of georesources, are time dependent. The changes in time of the seismicity cause that the related seismic hazard changes in time as well. We present here the Seismic HAzard Parameters Evaluation (SHAPE) tool, which enables an assessment of the temporal changes of the mean return period (MRP) of a seismic event of a given magnitude and the exceedance probability (EP) of a given magnitude within a predefined time period. SHAPE is an open‐source software package, written in MATLAB (see Data and Resources), based on the online probabilistic seismic hazard analysis applications available on IS‐EPOS platform of thematic core service anthropogenic hazards of European Plate Observing System (EPOS). SHAPE is developed in two standalone versions allowing the user to select a variety of options and parameters to determine the values of EP and MRP, assuming different magnitude distribution models. The first software version (SHAPE_ver1) provides interactive parameter selection and data filtering through a graphical user interface environment, whereas the second wrapper‐script‐based version (SHAPE_ver2) allows fast implementation and fine‐tuning of parameters. The program is particularly useful for anthropogenic seismicity cases, to monitor the changes of seismic response to technological operations, and to control the effectiveness of the undertaken hazard mitigation measures. As an example, two applications of SHAPE in case studies from the northwestern part of The Geysers geothermal field, California, and Song Tranh 2 surface water reservoir, Vietnam, are demonstrated.

%0 Journal Article
%@ 1895-6572
%A Leptokaropoulos, Konstantinos Michail
%A Staszek, Monika
%A Institute of GeophysicsPolish Academy of SciencesWarsawPoland,
%A Institute of GeophysicsPolish Academy of SciencesWarsawPoland,
%D 2019
%F epos:2208
%I Versita, Warsaw and Springer-Verlag Berlin Heidelberg
%J Acta Geophysica
%K Injection-induced seismicity Magnitude distribution Geothermal fields Statistical seismology
%N 1
%P 327-339
%T Temporal response of magnitude distribution to fluid injection rates in The Geysers geothermal field
%U https://episodesplatform.eu/eprints/2208/
%V 67
%X The influence of fluid injection rates on the magnitude distribution of the seismicity which occurred in the NW part of The Geysers geothermal site is studied here. A direct comparison between injection rate changes and b value response is attempted after appropriate selection of data subsets. Due to the relatively small sample (1121 events, corresponding to an average rate of ~ 0.45 events/day), we also aggregated seismic activity into two families corresponding to increasing and decreasing injection rates, respectively. The b values were calculated as a function of time lag related to the injection activity. In agreement with previous studies, we found a statistically significant direct relation between b values and injection rate changes, which occurred at a zero or very short time lag (from 0 to ~ 15 days). However, the b value changes are related to the slope (i.e., the second derivative of injection volume), instead of the absolute values of injection rates. The increasing injection rates correspond to b = 1.18 ± 0.06, whereas the decreasing injection rates correspond to b = 1.10 ± 0.05. The corresponding values estimated by the repeated medians technique are b = 1.97 ± 0.20 and b = 1.50 ± 0.13. Both differences are significant at 0.05 level.

%0 Journal Article
%@ 1895-6572
%A Leptokaropoulos, Konstantinos Michail
%A Staszek, Monika
%A Cielesta, Szymon
%A Urban, Pawel
%A Olszewska, Dorota
%A Lizurek, Grzegorz
%A Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland,
%D 2017
%F epos:1864
%I Springer Verlag
%J Acta Geophysica
%K Induced seismicity, Magnitude distribution,  Bobrek mine, Time-dependent hazard assessment
%T Time-dependent seismic hazard in Bobrek coal mine, Poland,  assuming different magnitude distribution estimations
%U https://episodesplatform.eu/eprints/1864/
%X The purpose of this study is to evaluate seismic  hazard parameters in connection with the evolution of  mining operations and seismic activity. The time-dependent  hazard parameters to be estimated are activity rate,  Gutenberg–Richter b-value, mean return period and  exceedance probability of a prescribed magnitude for  selected time windows related with the advance of the  mining front. Four magnitude distribution estimation  methods are applied and the results obtained from each one  are compared with each other. Those approaches are  maximum likelihood using the unbounded and upper  bounded Gutenberg–Richter law and the non-parametric  unbounded and non-parametric upper-bounded kernel  estimation of magnitude distribution. The method is  applied for seismicity occurred in the longwall mining of  panel 3 in coal seam 503 in Bobrek colliery in Upper  Silesia Coal Basin, Poland, during 2009–2010. Applications  are performed in the recently established Web-Platform  for Anthropogenic Seismicity Research, available at  https://tcs.ah-epos.eu/.

%0 Journal Article
%@ 0956-540X
%A Leptokaropoulos, Konstantinos Michail
%A Staszek, Monika
%A Lasocki, Stanislaw
%A Martinez-Garzon, Patricia
%A Kwiatek, Grzegorz
%A Institute of Geophysics, Polish Academy of Sciences,
%A Institute of Geophysics, Polish Academy of Sciences,
%A Institute of Geophysics, Polish Academy of Sciences,
%A Helmholtz-Centre Potsdam, GFZ German Research Centre for Geosciences,
%A Helmholtz-Centre Potsdam, GFZ German Research Centre for Geosciences,
%D 2017
%F epos:2029
%I Oxford University Press
%J Geophysical Journal International
%N 2
%P 1157-1166
%T Evolution of seismicity in relation to fluid injection in the North-Western part of The Geysers geothermal field
%U https://episodesplatform.eu/eprints/2029/
%V 212
%X The Geysers geothermal field located in California, USA, is the largest geothermal site in the world, operating since the 1960s. We here investigate and quantify the correlation between temporal seismicity evolution and variation of the injection data by examination of time-series through specified statistical tools (binomial test to investigate significant rate changes, cross correlation between seismic and injection data, b-value variation analysis). To do so, we utilize seismicity and operational data associated with two injection wells (Prati-9 and Prati-29) which cover a time period of approximately 7 yr (from November 2007 to August 2014). The seismicity is found to be significantly positively correlated with the injection rate. The maximum correlation occurs with a seismic response delay of ∼2 weeks, following injection operations. Those results are very stable even after considering hypocentral uncertainties, by applying a vertical shift of the events foci up to 300 m. Our analysis indicates also time variations of b-value, which exhibits significant positive correlation with injection rates.

%0 Journal Article
%@ 0033-4553
%A Lizurek, Grzegorz
%A Institute of Geophysics, Polish Academy of SciencesWarsawPoland,
%D 2017
%F epos:1881
%I Springer Verlag
%J Pure and Applied Geophysics
%K Anthropogenic seismicity, moment tensor, focal mechanism, induced seismicity, intraplate seismicity
%N 1
%P 197-212
%T Full Moment Tensor Inversion as a Practical Tool in Case of Discrimination of Tectonic and Anthropogenic Seismicity in Poland
%U https://episodesplatform.eu/eprints/1881/
%V 174
%X Tectonic seismicity in Poland is sparse. The biggest event was located near Myślenice in 17th century of magnitude 5.6. On the other hand, the anthropogenic seismicity is one of the highest in Europe related, for example, to underground mining in Upper Silesian Coal Basin (USCB) and Legnica Głogów Copper District (LGCD), open pit mining in “Bełchatów” brown coal mine and reservoir impoundment of Czorsztyn artificial lake. The level of seismic activity in these areas varies from tens to thousands of events per year. Focal mechanism and full moment tensor (MT) decomposition allow for deeper understanding of the seismogenic process leading to tectonic, induced, and triggered seismic events. The non-DC components of moment tensors are considered as an indicator of the induced seismicity. In this work, the MT inversion and decomposition is proved to be a robust tool for unveiling collapse-type events as well as the other induced events in Polish underground mining areas. The robustness and limitations of the presented method is exemplified by synthetic tests and by analyzing weak tectonic earthquakes. The spurious non-DC components of full MT solutions due to the noise and poor focal coverage are discussed. The results of the MT inversions of the human-related and tectonic earthquakes from Poland indicate this method as a useful part of the tectonic and anthropogenic seismicity discrimination workflow.

%0 Journal Article
%@ 0040-1951
%A Lizurek, Grzegorz
%A Leptokaropoulos, Konstantinos
%A Wiszniowski, Jan
%A Van. Giang, Nguyen
%A Nowaczyńska, Izabela
%A Plesiewicz, Beata
%A Van, Dinh Quoc
%A Tymińska, Anna
%A Institute of Geophysics, Polish Academy of Sciences (IG PAS), Poland,
%A Ocean and Earth Science, University of Southampton, UK,
%A Institute of Geophysics, Polish Academy of Sciences (IG PAS), Poland,
%A Institute of Geophysics, Vietnamese Academy of Science and Technology (IGP VAST),,Viet Nam,
%A Institute of Geophysics, Polish Academy of Sciences (IG PAS), Poland,
%A Institute of Geophysics, Polish Academy of Sciences (IG PAS), Poland,
%A Institute of Geophysics, Vietnamese Academy of Science and Technology (IGP VAST),,Viet Nam,
%A Institute of Geophysics, Polish Academy of Sciences (IG PAS), Poland,
%D 2021
%F epos:2321
%I Elsevier
%J Tectonophysics
%K Reservoir-triggered seismicityFocal mechanismStress inversionAnthropogenic seismicityProbabilistic seismic hazard
%P 229121
%T Seasonal trends and relation to water level of reservoir-triggered seismicity in Song Tranh 2 reservoir, Vietnam
%U https://episodesplatform.eu/eprints/2321/
%V 820
%X Reservoir-triggered seismicity (RTS) has the potential to generate disastrous seismic events of M6 and bigger. Song Tranh 2 (STR2) is an artificial water reservoir located in Central Vietnam. High seismic activity has been observed in this area since the reservoir was first filled in 2011. The relation between water level and seismic activity in the Song Tranh area is complex, and previous studies have led to the conclusion that ongoing STR2 seismic activity is an example of the delayed response type of RTS. However, the first phase of the activity observed after impoundment has been deemed a rapid response type. There were three stages of the reservoir filling periods: first, a period of initial impoundment, hereinafter referred to as pre-gap period (from 05/01/2011 to 10/06/2012), then a gap period (from 10/06/2012 to 31/08/2013) where reservoir impoundment stopped and water was drained to minimum exploitation level, and finally, a third post-gap period (from 31/08/2013 to 19/06/2017). In this work, we prove that the gap in the filling of reservoir results to a 2-fold rise of seismicity rate. The re-filling of the reservoir results to a drop of activity rate, roughly equal to the pre-gap period, accompanied by a significant increase of b-value. As a consequence, after the gap, the exceedance probability is significantly lower in comparison to pre-gap and gap periods. We also proved that the seismicity recorded between 2013 and 2016 manifested seasonal trends related to water level changes during wet and dry seasons. The response of activity and its delay with respect to water level changes suggest that the main triggering factor is pore pressure change due to the significant water level changes observed. The findings indicate that water load and related pore pressure changes considerably influence seismic activity and stress orientation in this area.

%0 Journal Article
%@ 1383-4649
%A Lizurek, Grzegorz
%A Wiszniowski, Jan
%A Giang, Nguyen Van
%A Van, Dinh Quoc
%A Dung, Le Van
%A Tung, V. D.
%A Plesiewicz, Beata
%A Institute of Geophysics Polish Academy of SciencesWarszawaPoland,
%A Institute of Geophysics Polish Academy of SciencesWarszawaPoland,
%A Binh Duong UniversityThu Dau MotVietnam, Institute of GeophysicsHanoiVietnam,
%A Institute of GeophysicsHanoiVietnam,
%A Institute of GeophysicsHanoiVietnam,
%A Institute of Geological SciencesHanoiVietnam,
%A Institute of Geophysics Polish Academy of SciencesWarszawaPoland,
%D 2019
%F epos:2245
%I Springer Verlag
%J Journal of Seismology
%K Reservoir-triggered seismicity, Moment tensor, Seismic monitoring, Background seismicity
%T Background seismicity and seismic monitoring in the Lai Chau reservoir area
%U https://episodesplatform.eu/eprints/2245/
%X Reservoir-triggered seismic activity depends not only on the technical characteristics of the future reservoir (filling volume, the height of water column) but also on the seismo-tectonics and the natural seismic processes occurring in the area before construction of an artificial reservoir. Passive seismic monitoring was realised near Lai Chau (Vietnam) before the impoundment started. It allowed exploration of the natural seismicity in the area of the future dam. Locations of seismic events several months prior to the reservoir impoundment were observed with ten stations installed in the reservoir vicinity. Events were mainly located near the dam along the Da river headwaters fault. However, only four stations were available for the entire period before the impoundment. Despite the network limitations, completeness of seismic catalogue and b value were determined and may be used as a baseline for analysis of the seismicity in this area after impoundment. The magnitude completeness level is significantly smaller than in the broader seismogenic zones covering an area of the dam. The b value differs from the results obtained for regional seismicity of Northeastern Vietnam. The capability of the local network for moment tensor inversion was estimated with the use of synthetic data tests. Test results provided the requirements for the station number according to azimuthal coverage of the network to obtain the reliable full moment tensor (MT) solution. Preliminary analysis of the seismic activity after Lai Chau reservoir impoundment indicates some changes in activity related to the impoundment and reservoir exploitation.

%0 Journal Article
%@ 0037-1106
%A Lizurek, Grzegorz
%A Wiszniowski, Jan
%A Van Giang, Nguyen
%A Plesiewicz, Beata
%A Van, Dinh Quoc
%A Institute of Geophysics, Polish Academy of Sciences (IG PAS),
%A Institute of Geophysics, Polish Academy of Sciences (IG PAS),
%A Institute of Geophysics, Vietnam Academy of Science and Technology (IGP VAST),
%A Institute of Geophysics, Polish Academy of Sciences (IG PAS),
%A Institute of Geophysics, Vietnam Academy of Science and Technology (IGP VAST),
%D 2017
%F epos:2024
%I Seismological Society of America
%J Bulletin of the Seismological Society of America
%P 1-13
%T Clustering and Stress Inversion in the Song Tranh 2 Reservoir, Vietnam
%U https://episodesplatform.eu/eprints/2024/
%X The seismicity in the vicinity of the Song Tranh 2 reservoir that commenced in late 2010 is an example of reservoir‐induced seismicity. Moment tensor (MT) solutions are mostly normal‐faulting mechanisms with shearing as the main component of full MT, which suggest reservoir exploitation stress field changes as a triggering origin of this seismicity. However, the local tectonic stress field plays a role in the seismogenic process, which is accelerated by the reservoir exploitation. Two main orientations of discontinuities reactivated by reservoir exploitation are identified, with clustering of events located in two main areas: northern and southern. In addition to the northern cluster (NC) and southern cluster (SC), further smaller clusters are distinguishable, assuming both clustering of epicenters and similarity of focal mechanisms as the clustering criteria. Maximum seismic activities in clusters appear in different periods, with high seismicity in the SC preceding that in the NC. The results indicate significant differences between the NC and SC. It is shown that the SC is an example of rapid triggering, whereas the NC is a delayed triggering type. Also, magnitude distribution differs between the NC ( b≈1.1b≈1.1 ) and SC ( b≈1.3b≈1.3 ).

%0 Journal Article
%@ 2045-2322
%A Lopez-Comino, Jose Angel
%A Cesca, Simone
%A Jarosławski, Janusz
%A Montcoudiol, Nelly
%A Heimann, Sebastian
%A Dahm, Torsten
%A Lasocki, Stanislaw
%A Gunning, Andrew
%A Capuano, Paolo
%A Ellsworth, William L.
%A GFZ German Research Centre for Geosciences, Potsdam, Germany.,
%A GFZ German Research Centre for Geosciences, Potsdam, Germany.,
%A Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland.,
%A School of Engineering, University of Glasgow,UK.,
%A GFZ German Research Centre for Geosciences, Potsdam, Germany.,
%A GFZ German Research Centre for Geosciences, Potsdam, Germany.,
%A Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland.,
%A RSKW Ltd, Stirling, United Kingdom.,
%A Dipartimento di Fisica, Università degli Studiy di Salerno, Fisciano, Italy.,
%A Department of Geophysics, Stanford University, Stanford, USA.,
%D 2018
%F epos:2100
%I Nature Publishing Group
%J Scientific Reports
%N 1
%T Induced seismicity response of hydraulic fracturing: results of a multidisciplinary monitoring at the Wysin site, Poland
%U https://episodesplatform.eu/eprints/2100/
%V 8
%X Shale oil and gas exploitation by hydraulic fracturing experienced a strong development worldwide over  the last years, accompanied by a substantial increase of related induced seismicity, either consequence  of fracturing or wastewater injection. In Europe, unconventional hydrocarbon resources remain  underdeveloped and their exploitation controversial. In UK, fracturing operations were stopped after  the Mw 2.3 Blackpool induced earthquake; in Poland, operations were halted in 2017 due to adverse oil  market conditions. One of the last operated well at Wysin, Poland, was monitored independently in the  framework of the EU project SHEER, through a multidisciplinary system including seismic, water and air  quality monitoring. The hybrid seismic network combines surface mini-arrays, broadband and shallow  borehole sensors. This paper summarizes the outcomes of the seismological analysis of these data.  Shallow artifcial seismic noise sources were detected and located at the wellhead active during the  fracturing stages. Local microseismicity was also detected, located and characterised, culminating in  two events of Mw 1.0 and 0.5, occurring days after the stimulation in the vicinity of the operational well,  but at very shallow depths. A sharp methane peak was detected ~19hours after the Mw 0.5 event. No  correlation was observed between injected volumes, seismicity and groundwater parameters.

%0 Journal Article
%@ 0956-540X
%A Lopez-Comino, Jose Angel
%A Cesca, Simone
%A Kriegerowski, Marius
%A Heimann, Sebastian
%A Dahm, Torsten
%A Mirek, Janusz
%A Lasocki, Stanislaw
%A GFZ German Research Centre for Geosciences, Telegrafenberg, Potsdam, Germany,
%A GFZ German Research Centre for Geosciences, Telegrafenberg,  Potsdam, Germany,
%A GFZ German Research Centre for Geosciences, Telegrafenberg, Potsdam, Germany,
%A GFZ German Research Centre for Geosciences, Telegrafenberg, Potsdam, Germany,
%A GFZ German Research Centre for Geosciences, Telegrafenberg, Potsdam, Germany,
%A Institute of Geophysics, Polish Academy of Sciences,  Warsaw, Poland,
%A Institute of Geophysics, Polish Academy of Sciences,  Warsaw, Poland,
%D 2017
%F epos:1926
%I Oxford University Press
%J Geophysical Journal International
%K Earthquake interaction, forecasting, and prediction, Earthquake monitoring and test-ban treaty verification, Induced seismicity
%N 1
%P 42-55
%T Monitoring performance using synthetic data for induced microseismicity by hydrofracking at the Wysin site (Poland)
%U https://episodesplatform.eu/eprints/1926/
%V 210
%X Ideally, the performance of a dedicated seismic monitoring installation should be assessed prior to the observation of target seismicity. This work is focused on a hydrofracking experiment monitored at Wysin, NE Poland. A microseismic synthetic catalogue is generated to assess the monitoring performance during the pre-operational phase, where seismic information only concerns the noise conditions and the potential background seismicity. Full waveform, accounting for the expected spatial, magnitude and focal mechanism distributions and a realistic local crustal model, are combined with real noise recording to produce either event based or continuous synthetic waveforms. The network detection performance is assessed in terms of the magnitude of completeness (Mc) through two different techniques. First, we use an amplitude threshold, taking into the ratio among the maximal amplitude of synthetic waveforms and station-dependent noise levels, for different values of signal-to-noise ratio. The detection probability at each station is estimated for the whole data set and extrapolated to a broader range of magnitude and distances. We estimate an Mc of about 0.55, when considering the distributed network, and can further decrease Mc to 0.45 using arrays techniques. The second approach, taking advantage on an automatic, coherence-based detection algorithm, can lower Mc to ∼ 0.1, at the cost of an increase of false detections. Mc experiences significant changes during day hours, in consequence of strongly varying noise conditions. Moreover, due to the radiation patterns and network geometry, double-couple like sources are better detected than tensile cracks, which may be induced during fracking.

%0 Journal Article
%@ 0033-4553
%A Mendecki, Maciej J.
%A Wojtecki, Łukasz
%A Zuberek, Wacław M.
%A Faculty of Earth SciencesUniversity of Silesia in KatowiceSosnowiecPoland,
%A Central Mining InstituteKatowicePoland,
%A Faculty of Earth SciencesUniversity of Silesia in KatowiceSosnowiecPoland,
%D 2019
%F epos:2215
%I Springer Verlag
%J Pure and Applied Geophysics
%T Case Studies of Seismic Energy Release Ahead of Underground Coal Mining Before Strong Tremors
%U https://episodesplatform.eu/eprints/2215/
%X We would like to test the concept that induced seismicity prior to relatively large mining tremor (ML > 2.5, E > 106J) can be inferred from the cumulative Benioff strain release (BSR) as power law time-to-failure before the strong event. This study presents the application of accelerating BSR prior to a large earthquake, widely used in natural seismicity, for analysis of this phenomenon in induced seismicity. The Benioff strain release is quantified as accelerated releases of cumulative (square root sum) of seismic energy in the time series. During the study, five sequences were extracted from the seismic catalogues from two Polish hard coal mines: exhausted Bobrek Mine (data form the IS-EPOS Platform) and from a mine belonging to the Polish Mining Group. Next, a search radius was used to select precursory events and to indicate the type of processes occurring in the coal seam and its vicinity. The fitted power law of cumulative Benioff strain release showed changes of m-parameter. If the value of m was lower than 1.0, the process was regarded as an accelerating-like and if m was higher than 1.0—as a quiescence-like. The investigation of m-parameter vs. the search radius showed the general behaviour of the rock mass in the studied areas and allowed to evaluate the relationship between the critical radius and magnitude of the target event. The obtained scaling relation log(Rc) ~ 0.35 ML is similar to these reported by other authors who analysed natural seismicity which might suggest that the scaling relation works in a wide range of magnitudes.

%0 Journal Article
%@ 0013-7952
%A Mendecki, Maciej Jan
%A Szczygiel, Jacek
%A Lizurek, Grzegorz
%A Teper, Leslaw
%A Institute of Earth Sciences, Faculty of Natural Sciences, University of Silesia in Katowice,,
%A Institute of Earth Sciences, Faculty of Natural Sciences, University of Silesia in Katowice,,
%A Institute of Geophysics, Polish Academy of Sciences, Ksiecia Janusza 64, Warsaw, Poland,
%A Institute of Earth Sciences, Faculty of Natural Sciences, University of Silesia in Katowice,,
%D 2020
%F epos:2265
%I Elsevier Science
%J Engineering Geology
%K Stress inversion, Focal mechanisms, Triggered seismicity, Upper Silesian Coal Basin, IS-EPOS Platform
%P 105728
%T Mining-triggered seismicity governed by a fold hinge zone: The Upper Silesian Coal Basin, Poland
%U https://episodesplatform.eu/eprints/2265/
%V 274
%X Mining tremor mechanisms and principal stress directions were analysed in order to compare characteristics of seismic events and stress regimes with tectonic settings in the Bytom Syncline, located in the Upper Silesian Coal Basin. The results of seismic moment tensor inversion calculated for 41 events with magnitudes > M2.0 were used to trace changes in types of mechanism (normal, strike-slip, reverse) with the progress of mining from Panel 3, coal seam 503, Bobrek Mine. The data was sourced from the IS-EPOS Platform, an open data infrastructure for the study of anthropogenic hazards linked to georesource exploitation. The foci were located below the seam and followed a longwall excavation. The computed mechanisms and distribution of spatial-temporal events enabled three clusters representing three different stages of stress regimes to be distinguished. The calculated principal stress axes indicated the main stress directions present in the studied area, enabling a local model of the derivative pattern of neotectonic deformation to be described. The regime changed from horizontal extension in the syncline limb (first cluster) to transpression (second cluster) to dominating compression in the hinge (third cluster), resulting in reverse fault production. Finally, the results revealed the causes of seismicity in the studied area and showed that the studied events had been mostly triggered.

%0 Journal Article
%@ 0956-540X
%A Molina, I
%A Velásquez, J S
%A Rubinstein, J L
%A Garcia-Aristizabal, A
%A Dionicio, V
%A Servicio Geológico Colombiano-SGC, Colombia,
%A Servicio Geológico Colombiano-SGC, Colombia,
%A United States Geological Survey—USGS,
%A Istituto Nazionale di Geofisica e Vulcanologia, Bologna, Italy,,
%A Servicio Geológico Colombiano-SGC, Colombia,
%D 2020
%F epos:2320
%I Oxford University Press
%J Geophysical Journal International
%K Fracture and flow, Earthquake dynamics, Earthquake source observations, Induced seismicity
%N 2
%P 777-791
%T Seismicity induced by massive wastewater injection near Puerto Gaitán, Colombia
%U https://episodesplatform.eu/eprints/2320/
%V 223
%X Seven years after the beginning of a massive wastewater injection project in eastern Colombia, local earthquake activity increased significantly. The field operator and the Colombian Geological Survey immediately reinforced the monitoring of the area. Our analysis of the temporal evolution of the seismic and injection data together with our knowledge of the geological parameters of the region indicate that the surge of seismicity is being induced by the re-injection of produced water into the same three producing reservoirs. Earthquake activity began on known faults once disposal rates had reached a threshold of ∼2 × 106 m3 of water per month. The average reservoir pressure had remained constant at 7.6 MPa after several years of production, sustained by a large, active aquifer. Surface injection pressures in the seismically active areas remain below 8.3 MPa, a value large enough to activate some of the faults. Since faults are mapped throughout the region and many do not have seismicity on them, we conclude that the existence of known faults is not the only control on whether earthquakes are generated. Stress conditions of these faults are open to future studies. Earthquakes are primarily found in four clusters, located near faults mapped by the operator. The hypocentres reveal vertical planes with orientations consistent with focal mechanisms of these events. Stress inversion of the focal mechanisms gives a maximum compression in the direction ENE-WSW, which is in agreement with borehole breakout measurements. Since the focal mechanisms of the earthquakes are consistent with the tectonic stress regime, we can conclude that the seismicity is resulting from the activation of critically stressed faults. Slip was progressive and seismic activity reached a peak before declining to few events per month. The decline in seismicity suggests that most of the stress has been relieved on the main faults. The magnitude of a large majority of the recorded earthquakes was lower than 4, as the pore pressure disturbance did not reach the mapped large faults whose activation might have resulted in larger magnitude earthquakes. Our study shows that a good knowledge of the local fault network and conditions of stress is of paramount importance when planning a massive water disposal program. These earthquakes indicate that while faults provide an opportunity to dispose produced water at an economically attractive volume–pressure ratio, the possibility of induced seismicity must also be considered.

%0 Journal Article
%@ 1876-6102
%A Montcoudiol, Nelly
%A Isherwood, Catherine
%A Gunning, Andrew
%A Kelly, Thomas
%A Younger, P. L.
%A Exploitation of shale gas by hydraulic fracturing (fracking) is highly controversial and concerns have been raised regarding induced risks from this technique. As part of the EU-funded SHEER Project, a shallow aquifer used for drinking water, overlying a,
%A RSKW, Stirling University Innovation Park, Stirling FK9 4NF, UK,
%A RSKW, Stirling University Innovation Park, Stirling FK9 4NF, UK,
%A RSKW, Stirling University Innovation Park, Stirling FK9 4NF, UK,
%A School of Engineering, University of Glasgow, Glasgow G12 8QQ, UK,
%D 2017
%F epos:2052
%I Elsevier
%J Energy Procedia
%K shale gas,environmental impacts, monitoring, Quaternary aquifer
%P 106-115
%T Shale gas impacts on groundwater resources: Understanding the behavior of a shallow aquifer around a fracking site in Poland
%U https://episodesplatform.eu/eprints/2052/
%V 125
%X Exploitation of shale gas by hydraulic fracturing (fracking) is highly controversial and concerns have been raised regarding induced risks from this technique. As part of the EU-funded SHEER Project, a shallow aquifer used for drinking water, overlying a zone of active shale-gas fracking, has been monitored for more than a year. Early results reveal the functioning of the shallow aquifer and hydrochemistry, focusing on the identification of potential impacts from the shale gas operation. This stage is an essential precursor to modeling impact scenarios of contamination and to predict changes in the aquifer.

%0 Journal Article
%@ 23003960
%A Mutke, Grzegorz
%A Kotyrba, Andrzej
%A Lurka, Adam
%A Olszewska, Dorota
%A Dykowski, Przemysław
%A Borkowski, Andrzej
%A Araszkiewicz, Andrzej
%A Baranski, Adam
%A Central Mining Institute, 40-166, Katowice, Pl. Gwarków1, Poland,
%A Central Mining Institute, 40-166, Katowice, Pl. Gwarków1, Poland,
%A Central Mining Institute, 40-166, Katowice, Pl. Gwarków1, Poland,
%A Institute of Geophysics, Polish Academy of Sciences, 01-452, Warszawa, Księcia Janusza 64, Poland,
%A Institute of Geodesy and Cartography, 02-679, Warszawa, Jacka Kaczmarskiego 27, Poland,
%A Wrocław University of Environmental and Life Sciences, 50-375, Wocław, CK Norwida 25, Poland,
%A Military University of Technology, 00-908, Warszawa 46, Gen. Witolda Urbanowicza 2, Poland,
%A Polish Mining Group S.A., 40-039, Katowice, Powstańców 30, Poland,
%D 2019
%F epos:2238
%I Elsevier
%J Journal of Sustainable Mining
%K Coal basin, Mining, Geodynamics, Geophysics, Monitoring systems
%N 4
%P 198-207
%T Upper Silesian Geophysical Observation System A unit of the EPOS project
%U https://episodesplatform.eu/eprints/2238/
%V 18
%X The aim of the paper is to present the structure and research potential of the newly created measurement and information system for observing dynamic phenomena occurring in the Earth's crust in the Upper Silesian Coal Basin (USCB) in Poland as a result of mining activities. The structure of the system is similar to the one developed for monitoring the movements of the European tectonic plate under the European Plate Observation System (EPOS) programme. The measurement part of the system consists of stationary devices and sensors working in monitoring mode, installed in various locations of the USCB, both on the surface and underground, as well as data sets from periodically performed measurements using land, air and satellite techniques. The IT part of the system will create a local data centre with specialized and dedicated processing and modelling software in which all measurement data will be archived and processed to a form which enables the analysis of the short and long-term impact of mining operations on the environment. As one of the elements of the system will be observations of the short and long-term gravity and morphology changes, the collected data will enable research in the field of the geodynamics of mining areas to be conducted.

%0 Journal Article
%@ 1895-6572
%A Olszewska, Dorota
%A Lasocki, Stanislaw
%A Leptokaropoulos, Konstantinos Michail
%A Institute of Geophysics, Polish Academy of Sciences,
%A Institute of Geophysics, Polish Academy of Sciences,
%A Institute of Geophysics, Polish Academy of Sciences,
%D 2017
%F epos:1941
%I Versita, Warsaw and Springer-Verlag Berlin Heidelberg
%J Acta Geophysica
%K Stationary seismic process, Mining-induced seismicity,   Internal correlations,
%P 1-9
%T Non-stationarity and internal correlations of the occurrence process of mining-induced seismic events
%U https://episodesplatform.eu/eprints/1941/
%X A point process, e.g., the seismic process, is potentially predictable when it is non-stationary, internally correlated or both. In this paper, an analysis of the occurrence process of mining-induced seismic events from Rudna copper mine in Poland is presented. Stationarity and internal correlation are investigated in complete seismic time series and segmentally in subseries demonstrating relatively stable seismicity rates. It is shown that the complete seismic series are non-stationary; however, most of their shorter subseries become stationary. In the stationary subseries, the distribution of interevent time is closer to the exponential distribution, which is characteristic for the Poisson process. However, in most of these subseries, the differences between the interevent time and Poisson distributions are still significant, revealing correlations among seismic events.

%0 Journal Article
%@ 2045-2322
%A Orlecka-Sikora, Beata
%A Cielesta, Szymon
%A Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland,
%A Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland,
%D 2020
%F epos:2247
%I Nature Research
%J Scientific Reports
%N 4016
%T Evidence for subcritical rupture of injection-induced earthquakes
%U https://episodesplatform.eu/eprints/2247/
%V 10
%X Seismicity induced by geo-engineering operations may be hazardous for people, infrastructure and the environment. The crucial information for assessing induced seismic hazards and related risks is knowledge of the time-dependent strength of rocks and the deformation due to fluid injection. Our studies of seismic and injection data from a geothermal field indicate that pressurized injections lead to rock fracturing at stress levels below the rock toughness, i.e., subcritical fracture growth. We provide a relation between the rate of this subcritical fracture growth and the injection rate. Based on this relation, we estimate the maximum subcritical magnitude. We hypothesize that subcritical fracture growth may be controlled by the amount of stress asymmetry, i.e., the relative values of the principal stresses. We discuss the conditions under which the subcritical fracturing regime can transform to a critical state and critical rupture may occur. We present the possibility of using these results in the operational reservoir to manage seismic hazards.

%0 Journal Article
%@ 1895-6572
%A Orlecka-Sikora, Beata
%A Cielesta, Szymon
%A Lasocki, Stanislaw
%A Institute of Geophysics Polish Academy of Sciences, Warsaw, Poland,
%A Institute of Geophysics Polish Academy of Sciences, Warsaw, Poland,
%A Institute of Geophysics Polish Academy of Sciences, Warsaw, Poland,
%D 2018
%F epos:2137
%I Springer Verlag
%J Acta Geophysica
%K Fluid injection Induced seismicity Fracture network Equivalent dimensions
%N 1
%P 341-350
%T Tracking the development of seismic fracture network from The Geysers geothermal field
%U https://episodesplatform.eu/eprints/2137/
%V 67
%X Underground fluid injections result in rock mass fracturing. The associated environmental hazards in a significant part stem from a possibility for linking these fractures. The resultant crevices may allow for an undesired and hazardous fluid migration. We studied the fracture linking problem on data from a part of The Geysers geothermal field in California, USA. We parameterized seismic events by the distance between hypocenter and injecting well, by the angle between the position vector of hypocentre and the maximum horizontal stress direction and by the angle of rotation required to turn the event’s double-couple mechanism into the prevailing in this area faults’ orientation. To make these parameters comparable, we transformed them to equivalent dimensions. Based on distances between events in the transformed parameter space, we divided the seismic events into clusters. The percentage of potentially linked fractures in clusters was greater at low than at high injection rate.

%0 Journal Article
%@ 0033-4553
%A Orlecka-Sikora, Beata
%A Lasocki, Stanislaw
%A Institute of Geophysics Polish Academy of Sciences, Warsaw, Poland,
%D 2016
%F epos:1863
%I Springer Verlag
%J Pure and Applied Geophysics
%K Aggregated uncertainty in the activity rate and magnitude magnitude cumulative distribution function interval estimation of seismic hazard functions resampling methods bootstrap jackknife
%T Interval Estimation of Seismic Hazard Parameters
%U https://episodesplatform.eu/eprints/1863/
%X The paper considers Poisson temporal occurrence of earthquakes and presents a way to integrate uncertainties of the estimates of mean activity rate and magnitude cumulative distribution function in the interval estimation of the most widely used seismic hazard functions, such as the exceedance probability and the mean return period. The proposed algorithm can be used either when the Gutenberg–Richter model of magnitude distribution is accepted or when the nonparametric estimation is in use. When the Gutenberg–Richter model of magnitude distribution is used the interval estimation of its parameters is based on the asymptotic normality of the maximum likelihood estimator. When the nonparametric kernel estimation of magnitude distribution is used, we propose the iterated bias corrected and accelerated method for interval estimation based on the smoothed bootstrap and second-order bootstrap samples. The changes resulted from the integrated approach in the interval estimation of the seismic hazard functions with respect to the approach, which neglects the uncertainty of the mean activity rate estimates have been studied using Monte Carlo simulations and two real dataset examples. The results indicate that the uncertainty of mean activity rate affects significantly the interval estimates of hazard functions only when the product of activity rate and the time period, for which the hazard is estimated, is no more than 5.0. When this product becomes greater than 5.0, the impact of the uncertainty of cumulative distribution function of magnitude dominates the impact of the uncertainty of mean activity rate in the aggregated uncertainty of the hazard functions. Following, the interval estimates with and without inclusion of the uncertainty of mean activity rate converge. The presented algorithm is generic and can be applied also to capture the propagation of uncertainty of estimates, which are parameters of a multiparameter function, onto this function.

%0 Journal Article
%@ 2052-4463
%A Orlecka-Sikora, Beata
%A Lasocki, Stanislaw
%A Kocot, Joanna
%A Szepieniec, Tomasz
%A Grasso, Jean-Robert
%A Garcia-Aristizabal, Alexander
%A Schaming, Marc
%A Urban, Pawel
%A Jones, Glenda
%A Stimpson, Ian
%A Dineva, Savka
%A Salek, Piotr
%A Leptokaropoulos, Konstantinos Michail
%A Lizurek, Grzegorz
%A Olszewska, Dorota
%A Schmittbuhl, Jean
%A Kwiatek, Grzegorz
%A Blanke, Aglaja
%A Saccarotti, Gilberto
%A Chodzinska, Karolina
%A Rudzinski, Lukasz
%A Dobrzycka, Izabela
%A Mutke, Grzegorz
%A Baranski, Adam
%A Pierzyna, Aleksandra
%A Kozlovskaya, Elena
%A Nevalainen, Jouni
%A Kinscher, Jannes
%A Sileny, Jan
%A Sterzel, Mariusz
%A Cielesta, Szymon
%A Fischer, Tomas
%A Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland,
%A Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland,
%A ACC Cyfronet, AGH, Krakow, Poland,
%A ACC Cyfronet, AGH, Krakow, Poland,
%A Isterre, Grenoble Observatory, Grenoble, France,
%A Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Bologna, Via Donato Creti 12, 40128, Bologna, Italy,
%A Université de Strasbourg, CNRS, IPGS-UMR7516, Strasbourg, France,
%A Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland,
%A Keele University, Keele, UK,
%A Keele University, Keele, UK,
%A Luleå University of Technology, Luleå, Sweden,
%A Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland,
%A Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland,
%A Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland,
%A Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland,
%A Université de Strasbourg, CNRS, IPGS-UMR7516, Strasbourg, France,
%A Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Section 4.2: Geomechanics and Scientific Drilling, Telegrafenberg, 14473, Potsdam, Germany,
%A Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Section 4.2: Geomechanics and Scientific Drilling, Telegrafenberg, 14473, Potsdam, Germany,
%A Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Pisa. Via Cesare Battisti, 53 - 56125, Pisa, Italy,
%A Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland,
%A Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland,
%A Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland,
%A Central Mining Institute, Katowice, Poland,
%A Polska Grupa Górnicza S.A., Katowice, Poland,
%A Polska Grupa Górnicza S.A., Katowice, Poland,
%A Oulu Mining School and Sodankylä Geophysical Observatory, University of Oulu, Oulu, Finland,
%A Oulu Mining School and Sodankylä Geophysical Observatory, University of Oulu, Oulu, Finland,
%A Institut national de l’environnement industriel et des risques, Nancy, France View author publications,
%A Institute of Geophysics, Academy of Sciences, CR, Prague, Czech Republic View author publications,
%A ACC Cyfronet, AGH, Krakow, Poland,
%A Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland,
%A Institute of Geophysics, Academy of Sciences, CR, Prague, Czech Republic,
%D 2020
%F epos:2248
%I Nature Research
%J Scientific Data
%N 89
%T An open data infrastructure for the study of anthropogenic hazards linked to georesource exploitation
%U https://episodesplatform.eu/eprints/2248/
%V 7
%X Mining, water-reservoir impoundment, underground gas storage, geothermal energy exploitation and hydrocarbon extraction have the potential to cause rock deformation and earthquakes, which may be hazardous for people, infrastructure and the environment. Restricted access to data constitutes a barrier to assessing and mitigating the associated hazards. Thematic Core Service Anthropogenic Hazards (TCS AH) of the European Plate Observing System (EPOS) provides a novel e-research infrastructure. The core of this infrastructure, the IS-EPOS Platform (tcs.ah-epos.eu) connected to international data storage nodes offers open access to large grouped datasets (here termed episodes), comprising geoscientific and associated data from industrial activity along with a large set of embedded applications for their efficient data processing, analysis and visualization. The novel team-working features of the IS-EPOS Platform facilitate collaborative and interdisciplinary scientific research, public understanding of science, citizen science applications, knowledge dissemination, data-informed policy-making and the teaching of anthropogenic hazards related to georesource exploitation. TCS AH is one of 10 thematic core services forming EPOS, a solid earth science European Research Infrastructure Consortium (ERIC) (www.epos-ip.org).

%0 Journal Article
%@ 00401951
%A Orlecka-Sikora, Beata
%A Rudziński, Łukasz
%A Staszek, Monika
%A Lizurek, Grzegorz
%A Mizerski, Krzysztof
%A Institute of Geophysics, Polish Academy of Sciences, Department of Seismology,
%A Institute of Geophysics, Polish Academy of Sciences, Department of Seismology,
%A Institute of Geophysics, Polish Academy of Sciences, Department of Seismology,
%A Institute of Geophysics, Polish Academy of Sciences, Department of Seismology,
%A Institute of Geophysics, Polish Academy of Sciences, Department of Seismology,
%D 2023
%F epos:2426
%J Tectonophysics
%K Seismic swarms Reservoir impoundment triggered seismicity Intermittent rupture
%P 230005
%T Seismic swarms as intermittent quasi-static ruptures driven by pore pressure variations due to the water reservoir impoundment
%U https://episodesplatform.eu/eprints/2426/
%V 863
%X Seismic swarms are characterized as time-space clustered sequences of earthquakes without a dominating strong event. The occurrence of earthquake swarms has been observed in various environments and found out to be closely related to underground migration of fluids. Mechanical interactions between fluid-conduit properties of fault and rupture determine the spatio-temporal complexity of rupturing process and earthquake occurrence. Often, seismic swarms are triggered by Water Reservoir Impoundment (WRI). Although many studies have investigated the relationship between the pore pressure changes due to WRI and observed seismicity, hydromechanical models that explain the observed processes are limited. Here, we investigate the role of hydromechanical interactions in triggering earthquake swarms in WRI conditions, using data from the Song Tranh 2 Reservoir in Vietnam as an example. We found that seismic swarms evolve due to stress redistribution and subsequent induced fluid flow. Swarm sequences form interconnected rupture increments and their aggregated behaviour is similar to a single large earthquake that ruptures the fault segment at once. The evolution of friction with the mean slip retrieved from the swarm earthquakes exhibits both, slip weakening and strengthening stages, resembling linear slip-weakening friction. The effective slip over which the weakening is completed, is modulated by the pore pressure diffusion. These results provide insights into the physical mechanisms of seismic swarms and have implications for seismic hazard.

%0 Journal Article
%@ 0895-0695
%A Rudzinski, Lukasz
%A Lasocki, Stanislaw
%A Orlecka-Sikora, Beata
%A Wiszniowski, Jan
%A Olszewska, Dorota
%A Kokowski, Jakub
%A Mirek, Janusz
%A Institute of Geophysics, Polish Academy of Sciences, Warszawa, Poland,
%A Institute of Geophysics, Polish Academy of Sciences, Warszawa, Poland,
%A Institute of Geophysics, Polish Academy of Sciences, Warszawa, Poland,
%A Institute of Geophysics, Polish Academy of Sciences, Warszawa, Poland,
%A Institute of Geophysics, Polish Academy of Sciences, Warszawa, Poland,
%A Institute of Geophysics, Polish Academy of Sciences, Warszawa, Poland,
%A Institute of Geophysics, Polish Academy of Sciences, Warszawa, Poland,
%D 2021
%F epos:2292
%I Seismological Society of America
%J Seismological Research Letters
%T Integrating Data under the European Plate Observing System from the Regional and Selected Local Seismic Networks in Poland
%U https://episodesplatform.eu/eprints/2292/
%X High‐quality and open‐access seismic data are of great importance for both research and increasing public awareness of actual seismic hazards and risks. We present four seismic networks that currently operate in Poland: the backbone Polish Seismological Network (PLSN), which monitors natural teleseismic events as well as regional events from Poland, and three networks that mainly serve the monitoring of anthropogenic seismicity. The acquired data from all four networks are openly available through the European Plate Observing System (EPOS) Information Technology (IT) facilities: the PLSN data within the Observatories and Research Facilities for European Seismology–European Integrated Data Archive and the anthropogenic seismicity data episodes through the induced seismicity‐EPOS platform of EPOS Thematic Core Service Anthropogenic Hazards. For each network, we describe briefly the recorded seismic activity, the equipment and composition of the network, the acquisition system, and the data availability. Information from recent studies is used to demonstrate the scientific potential of the acquired anthropogenic seismicity data.

%0 Journal Article
%@ 00948276
%A Staszek, Monika
%A Orlecka-Sikora, Beata
%A Leptokaropoulos, Konstantinos Michail
%A Kwiatek, Grzegorz
%A Martinez-Garzon, Patricia
%A Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland,
%A Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland,
%A Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland,
%A Section 4.2: Geomechanics and Rheology, Helmholtz-Centre Potsdam, GFZ German Research Centre for Geosciences, Potsdam, Germany,
%A Section 4.2: Geomechanics and Rheology, Helmholtz-Centre Potsdam, GFZ German Research Centre for Geosciences, Potsdam, Germany,
%D 2017
%F epos:1994
%I Geophysical Research Letters
%J Geophysical Research Letters
%N 14
%P 7168-7176
%T Temporal static stress drop variations due to injection activity at The Geysers geothermal field, California
%U https://episodesplatform.eu/eprints/1994/
%V 44
%X We use a high-quality data set from the NW part of The Geysers geothermal field to determine  statistical significance of temporal static stress drop variations and their relation to injection rate changes.  We use a group of 322 seismic events which occurred in the proximity of Prati-9 and Prati-29 injection wells to  examine the influence of parameters such as moment magnitude, focal mechanism, hypocentral depth, and  normalized hypocentral distances from open-hole sections of injection wells on static stress drop changes.  Our results indicate that (1) static stress drop variations in time are statistically significant, (2) statistically  significant static stress drop changes are inversely related to injection rate fluctuations. Therefore, it is highly  expected that static stress drop of seismic events is influenced by pore pressure in underground fluid  injection conditions and depends on the effective normal stress and strength of the medium.

%0 Journal Article
%@ 2045-2322
%A Staszek, Monika
%A Rudzinski, Lukasz
%A Kwiatek, Grzegorz
%A Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland,
%A Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland,
%A Helmholtz-Centre Potsdam, GFZ German Research Centre for Geosciences, Section 4.2: Geomechanics and Scientific Drilling, Potsdam, Germany,
%D 2021
%F epos:2333
%I Nature Publishing Group
%J Scientific Reports
%N 1
%T Spatial and temporal multiplet analysis for identification of dominant fluid migration path at The Geysers geothermal field, California
%U https://episodesplatform.eu/eprints/2333/
%V 11
%X Multiplet analysis is based on the identification of seismic events with very similar waveforms which are used then to enhance seismological analysis e.g. by precise relocation of sources. In underground fluid injection conditions, it is a tool frequently used for imaging of subsurface fracture system. We identify over 150 repeatedly activated seismic sources within seismicity cluster induced by fluid injection in NW part of The Geysers geothermal field (California). Majority of multiple events (ME) occur along N–S oriented planar structure which we interpret as a fault plane. Remaining ME are distributed along structures interpreted as fractures, forming together a system of interconnected cracks enabling fluid migration. Temporal analysis reveals that during periods of relatively low fluid injection the proportion of ME to non-multiple events is higher than during periods of high injection. Moreover, ME which occur within the fault differ in activity rate and source properties from ME designating the fractures and non-multiple events. In this study we utilize observed differences between ME occurring within various structures and non-multiple events to describe hydraulic conditions within the reservoir. We show that spatial and temporal analysis of multiplets can be used for identification and characterization of dominant fluid migration paths.

%0 Journal Article
%A Toon, Sam
%A Keele University,
%D 2017
%F epos:2043
%I Keele University
%J SHEER Newsletter
%T THE EUROPEAN PLATE OBSERVING SYSTEM &  TCS Anthropogenic Hazards
%U https://episodesplatform.eu/eprints/2043/
%V 5

%0 Journal Article
%A Westwood, Rachel F.
%A Keele University,
%D 2016
%F epos:2042
%I Keele University
%J SHEER Newsletter
%T SHEER and EPOS-IP TCS AH
%U https://episodesplatform.eu/eprints/2042/
%V 2

%0 Journal Article
%@ 1895-7455
%A Wiszniowski, Jan
%A Giang, Nguyen Van
%A Plesiewicz, Beata
%A Lizurek, Grzegorz
%A Van, Dinh Quoc
%A Khoi, Le Quang
%A Lasocki, Stanislaw
%A Institute of Geophysics Polish Academy of Sciences, Warsaw, Poland,
%A Institute of Geophysics, Vietnam Academy of Science and Technology, Hanoi, Vietnam,
%A Institute of Geophysics Polish Academy of Sciences, Warsaw, Poland,
%A Institute of Geophysics Polish Academy of Sciences, Warsaw, Poland,
%A Institute of Geophysics, Vietnam Academy of Science and Technology, Hanoi, Vietnam,
%A Institute of Geophysics, Vietnam Academy of Science and Technology, Hanoi, Vietnam,
%A Institute of Geophysics Polish Academy of Sciences, Warsaw, Poland,
%D 2015
%F epos:1568
%I De Gruyter
%J Acta Geophysica
%K reservoir induced seismicity; seismic network; source parameters; focal mechanism; completeness of catalogs
%N 3
%P 843-862
%T Preliminary Results of Anthropogenic Seismicity Monitoring in the Region of Song Tranh 2 Reservoir, Central Vietnam
%U https://episodesplatform.eu/eprints/1568/
%V 63
%X 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.

%0 Journal Article
%@ 0098-3004
%A Wiszniowski, Jan
%A Plesiewicz, Beata
%A Lizurek, Grzegorz
%A Institute of Geophysics, Polish Academy of Sciences (IG PAS), Poland,
%A Institute of Geophysics, Polish Academy of Sciences (IG PAS), Poland,
%A Institute of Geophysics, Polish Academy of Sciences (IG PAS), Poland,
%D 2021
%F epos:2331
%I Elsevier
%J Computers & Geosciences
%P 104628
%T Machine learning applied to anthropogenic seismic events detection in Lai Chau reservoir area, Vietnam
%U https://episodesplatform.eu/eprints/2331/
%V 146
%X Automatic detection of seismic events is a useful tool for routine data processing. Effective detection saves time and effort in phase picking and events’ location, especially in areas with moderate seismicity at regional and local scales. The Lai Chau area in northern Vietnam is a good example of such a region. An additional difficulty in detection is the anthropogenic origin of reservoir-triggered seismicity observed in this region, where seismicity is non-stationary and there was no prior seismic activity. Neural network event detection was prepared to aid event identifications and further processing of seismic data. An automatic detection system was utilized to reduce the effort of manual interpretation of seismic signals in the region of the Lai Chau dam in North Vietnam while maintaining the detection of weak events at the same level. For this reason, a Single Layer Recurrent Neural Network (SLRNN) was applied. Compared to deep learning algorithms, fewer examples were needed to train the SLRNN. This paper presents a modified version of SLRNN, which additionally uses polarization analysis and the multi-stage learning process. In the first stage, the training data consists of events detected manually and disturbances selected visually by the operator. In the next stages, the earlier trained detection is validated in the successive recording periods. False detections together with new seismic events are added to the training set and the detection is retrained. The multi-stage process significantly reduces false detections. The software allows SLRNN to be used for routine seismic data processing.

%0 Conference Paper
%A Lasocki, Stanislaw
%A Orlecka-Sikora, Beata
%A Leptokaropoulos, Konstantinos Michail
%A Sterzel, Mariusz
%A Szepieniec, Tomasz
%A Kocot, Joanna
%A Mutke, Grzegorz
%A Baranski, Adam
%A Institute of GeophysicsPolish Academy of Sciences, Warsaw, Poland,
%A Institute of GeophysicsPolish Academy of Sciences, Warsaw, Poland,
%A Institute of GeophysicsPolish Academy of Sciences, Warsaw, Poland,
%A ACK Cyfronet AGH, Krakow, Poland,
%A ACK Cyfronet AGH, Krakow, Poland,
%A ACK Cyfronet AGH, Krakow, Poland,
%A Central Mining Institute, Katowice, Poland,
%A PGG, Katowice, Poland,
%B 16th World Conference on Earthquake
%C Santiago, Chile
%D 2017
%F epos:2040
%K Anthropogenic Hazards, Induced Seismicity, web-platform, Research Infrastructure for Georesources, EPOS
%P 1-12
%T IS-EPOS: A DIGITAL RESEARCH SPACE TO FACILITATE INTEGRATED APPROACH TO ANTHROPOGENIC SEISMIC HAZARDS
%U https://episodesplatform.eu/eprints/2040/
%X The problem of hazards induced by exploration and exploitation of georesources focuses growing interest of science, industry, public administration, NGO-s and general public. Anthropogenic seismicity, i.e. the undesired dynamic rockmass response to georesources exploitation, is one of the examples of unwanted by-products of technological occupation of humans. It becomes a real problem in areas previously known as aseismic and in association with quite diverse technological processes. The socioeconomic impact of the induced seismicity is very significant. Induced earthquakes can cause material loss, injuries and even fatalities. The anthropogenic seismic hazards are undoubtedly linked to particular inducing technologies. However, the rockmass reactions to inducing factors of the same physical kind have much in common. The research focused on common features of these reactions and transverse to inducing technologies seems to be the way to accelerate recognition of the problem. This can be accomplished only on through integration of research based on the most advanced ICT solutions. We present here IS-EPOS IT-platform, which is an open virtual access point for researchers studying anthropogenic seismicity and related hazards. The relevant seismic and non-seismic data are gathered in the so-called episodes of induced seismicity. The episode is a comprehensive data description of a seismic process, induced or triggered by human technological activity, which under certain circumstances can become hazardous for people, infrastructure and the environment. The episode consists of a time-correlated collectio n of seismic data representing the seismic process, technological data representing the technological activity, which is the cause of this process and all other relevant geodata describing the environment, in which the technological activity and its result or by-product, the seismic process take place. The IS-EPOS platform integrates presently six episodes of anthropogenic seismicity respectively linked to underground hard rock and coal mining in Poland, hydro energy production in Poland and Vietnam and geothermal energy production experiment in Germany. The researcher accessing the platform can make use of low level software services for data browsing, selecting and visualizing and a number of high level services for advanced data processing out of which the probabilistic seismic analysis service group is particularly rich. The IS-EPOS platform is a prototype of TCS Anthropogenic Hazards belonging to pan-European multidisciplinary research platform created within European P late Observing System long-term plan for the integration of national and transnational research infrastructures for solid Earth science in Europe.

%0 Conference Paper
%A Makuch, Mieszko
%A Malawski, Maciej
%A Kocot, Joanna
%A Szepieniec, Tomasz
%A AGH University of Science and Technology Department of Computer Science Krakow,Poland,
%A AGH University of Science and Technology Department of Computer Science Krakow,Poland,
%A AGH University of Science and Technology ACC Cyfronet AGH Krakow,Poland,
%A AGH University of Science and Technology ACC Cyfronet AGH Krakow,Poland,
%B 2020 IEEE/ACM Workflows in Support of Large-Scale Science (WORKS)
%C GA, USA
%D 2020
%F epos:2332
%P 25-32
%T Applying workflows to scientific projects represented in file system directory tree
%U https://episodesplatform.eu/eprints/2332/
%X Most workflow management systems represent scientific workflows as DAG (directed acyclic graph) and require to provide a workflow specification before the workflow can be executed. Workflow can be designed using a graphical interface or with textual workflow editing. For uses unacquainted with workflow abstraction, these systems can be complicated as it usually takes multiple steps to design abstract workflow specification. To reduce the learning curve and barriers to entry for inexperienced users, we have decided to create a workflow representation that is based on the well-known file system directory structure. In our representation, the workflow structure can be drawn from project organization space which is based on the file system directory tree. As a result, the proposed workflow representation is more natural and more intuitive for users who are already accustomed to the directory structure. The workflow structure is created on the fly as the user adds, executes and organizes services inside their workspace. We have used tree structure hierarchy to model a part-whole hierarchy between workflows, sub-workflows and individual services. Proposed solutions support modularity with multi-level sub-workflow nesting, encapsulation, workflow reuse and sharing, as well as automated workflow execution in a distributed infrastructure. The proposed model was implemented and evaluated on the IS-EPOS Platform [1], a real-world online workflow management system used to conduct research in the field of anthropogenic seismicity.

%0 Conference Paper
%A Olszewska, Dorota
%A Mutke, Grzegorz
%A Institute of Geophysics Polish Academy of Science, Warsaw, Poland,
%A GIG Central Mining Institute, Katowice, Poland,
%B 16th European Conference on Earthquake Engineering
%C Thessaloniki, Greece
%D 2018
%F epos:2123
%K amplification, downhole measurement, HVSR, transfer function
%T A STUDY OF SITE EFFECT USING SURFACE-DOWNHOLE SEISMIC DATA IN A MINING AREA
%U https://episodesplatform.eu/eprints/2123/
%X The aim of this study is to examine the phenomenon of site effect using surface-downhole seismic data caused by mining tremors in the Upper Silesia Coal Basin (USCB). The USCB is located in southern Poland and as a consequence of underground mining operations about 1000 mining tremors occur annually with a local magnitude of ML≥1.5. The strongest event which occurred on 09.02.2010 reached ML=4.2 and the peak ground acceleration (PGA) observed was approximately – 2 m/s2. Induced events which can be treated as minor shallow earthquakes also have an impact on the surface. Thus, monitoring of ground motion is carried out and provided by the Central Mining Institute in this area – the Upper Silesian Seismological Network USSN (data are available as “episode USCB” on the IS-EPOS platform at https://tcs.ah-epos.eu/).  Analysis of the site effect was done using data from two stations each containing 2 sensors, one on the surface and one 30 m downhole. The station includes one accelerometer on the surface and one in the 30 m downhole. This study was done using ground motion recordings of underground mining events with ML≥2.3 from January 2014 to June 2017. In the first step, the amplification factors were calculated as a ratio between the surface and downhole PGA. Next, transfer functions of both components were calculated using surface and downhole data and HVSR (Horizontal to Vertical Spectral Ratio) curves were obtained. All those results were compared with each other, particularly in terms of the impact of the vertical component. Profiles of sheer waves up to 30 m were also used in this study. The result shows that the vertical component is amplified in a different manner to that of the horizontal. Moreover, the results of these analyses allow for a better understanding of the amplification phenomena caused by the surface layer in this area.