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1

Vrancea intermediate-depth focal mechanism catalog: a useful instrument for local and regional stress field estimation

Andreea Craiu, Marius Craiu, Marius Mihai, Florinela Manea Elena, Alexandru Marmureanu

Acta Geophysica

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2023

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Vol. 71, no. 1

29--52

EN

The Vrancea seismic zone, located in the bend region of the South-Eastern Carpathians, is a unique area with both crustal and intermediate-depth seismic activity and is known as one of the most active seismic area in Europe. Moderate crustal seismicity is recorded all over the Carpathian region, but the far more intense activity occurs in a small subcrustal seismogenic volume beneath the SE‐bend of the Carpathian arc with about 20×50 km lateral and 110 km vertical extent (70–180 km depth). A unique slab geometry, likely preserved until the present, causes stress localization due to the slab bending and subsequent stress release resulting in large mantle earthquakes in the region. The main focus of this study is to determine the focal mechanisms for events with a magnitude larger than 2.7, between 2005 and 2020 and evaluate the current stress field along the Vrancea subcrustal region, from the derived fault plane solutions. The main style of faulting for Vrancea subcrustal events presents a predominant reverse one, with two main earthquakes categories: the first one with the nodal planes, oriented NE–SW parallel with the Carpathian Arc and the second one with the nodal planes, oriented NW–SE perpendicular on the Carpathian Arc. The results of stress inversion indicate a dominant thrust faulting style, with an average stress regime index of 2.87. The stress pattern shows similar partitioning with vertical extension in the slab and no preferred orientation in the overlying crust, showing a transition regime from the extensional regime in the Moesian Platform to the compressional regime in the Vrancea subcrustal zone.

2

Zagrożenia geologiczne w Polsce w 2021 roku

Wojciechowski Tomasz, Laskowicz Izabela, Kos Jarosław, Marciniec Paweł, Uścinowicz Grzegorz, Przyłucka Maria, Wódka Marcin

Przegląd Geologiczny

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2022

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Vol. 70, nr 9

617--626

EN

Geological hazards caused by landslides, earthquakes, erosion, land surface deformation and collapse in 2021 in Poland were among the average compared to recent years. They did, however, affect material losses. The Polish Geological Survey (PGS) recorded 41 events related to sudden landslide activations, which damaged or destroyed 17 road sections. Through ongoing monitoring of 72 landslides, 33 were shown to be active. In 2021, more than 5,200 landslides were identified and inventoried in Poland. Geodynamic monitoring performed by PGS recorded 611 seismic events in Poland, whose magnitudes reached M4.2. In addition, using satellite radar interferometry, continuation of land surface deformations was found mainly in mining areas. In 2021, there was a number of collapses of various origins. The paper is a brief report on the ongoing tasks of the Polish Geological Survey in the field of geological hazards and presents events that took place in Poland in 2021.

3

Zagrożenia geologiczne w Polsce w 2020 roku

Wojciechowski Tomasz, Laskowicz Izabela, Nescieruk Piotr, Marciniec Paweł, Uścinowicz Grzegorz, Czerwiński Tomasz, Perski Zbigniew

Przegląd Geologiczny

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2021

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Vol. 69, nr 5

303--311

EN

The paper describes geohazard events that took place in 2020 on the territory of Poland. The PGI is responsible for geohazard monitoring in four areas of interest :landslides and mass movements within the Landslide Counteracting System (LCS, SOPO in Polish), earthquakes within the Geodynamical Monitoring of Poland and ground motions within the Interferometric Terrain Deformations Monitoring of Poland, and coastal monitoring carried out by the Marine Geology Branch within a framework of the 4D Cartography. In 2020, there were no spectacular geohazard events; however, there were some permanently active phenomena, mostly landslides, which caused significant damages to the infrastructure.

4

Mitigating the seismic pounding of multi-story buildings in series using linear and nonlinear fluid viscous dampers

Elwardany Hytham, Jankowski Robert, Seleemah Ayman

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 4

1--16

EN

Seismic-induced pounding between adjacent buildings may have serious consequences, ranging from minor damage up to total collapse. Therefore, researchers try to mitigate the pounding problem using different methods, such as coupling the adjacent buildings with stiff beams, connecting them using viscoelastic links, and installing damping devices in each building individually. In the current paper, the effect of using linear and nonlinear fluid viscous dampers to mitigate the mutual pounding between a series of structures is investigated. Nonlinear finite-element analysis of a series of adjacent steel buildings equipped with damping devices was conducted. Contact surfaces with both contactor and target were used to model the mutual pounding. The results indicate that the use of linear or nonlinear dampers leads to the significant reduction in the response of adjacent buildings in series. Moreover, the substantial improvement of the performance of buildings has been observed for almost all stories. From the design point of view, it is concluded that dampers implemented in adjacent buildings should be designed to resist maximum force of 6.20 or 1.90 times the design independent force in the case of using linear or nonlinear fluid viscous dampers, respectively. Also, designers should pay attention to the design of the structural elements surrounding dampers, because considerable forces due to pounding may occur in the dampers at the maximum displaced position of the structure.

5

Fractured clasts in the Mt Currie Conglomerate at Kata Tjuta (Central Australia): evidence of Early Cambrian earthquakes?

Tokarski Antek K., Strzelecki Piotr J.

Geology, Geophysics and Environment

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2020

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Vol. 46, no. 1

29--33

EN

Lower Cambrian Mt Currie conglomerate at Kata Tjuta bornhardts (Central Australia) bears numerous fractured clasts. Clast-cutting fractures are restricted to particular clasts, the matrix of the conglomerate is not fractured. The fractures are tectonic joints of two sets. The joints were formed due to either seismic or aseismic deformation. In the former case, the fractures may result from Early Paleozoic earthquakes.

6

Seismic Behavior of Earth Dams With Different Reservoir Water Levels Under Near-Field and Far-Field Earthquakes

Asadi Masoud, Soltani Fazlollah, Sinvandi-Pour Abbas, Noroozinejad Farsangi Ehsan

Civil and Environmental Engineering Reports

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2020

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Vol. 30, no. 4

125--141

EN

The height of reservoir water is one of the important factors affecting the seismic behaviour of earth dams. A large number of earth dams have been constructed in different countries that are sometimes located in a high-risk geographical zone. The studies on the seismic behaviour of earth dams have been conducted for several decades. However, this study, considering the importance of the subject, it investigates the seismic behaviour of Sumbar rock-fill embankment dam under near- and far-field earthquakes with variation in the water level behind the dam. The ratio of water height of the dam to dam height is considered as an important indicator to investigate the seismic performance of these structures. The analyses were performed using the ABAQUS finite element platform, under 7 near-field and 7 far-field earthquake records. In this research, the changes in dam stresses, displacements, and failure of the dam have been discussed. The results indicated that the effect of near-field earthquakes on the seismic behaviour of earth dams is more significant than far-field earthquakes.

7

Investigating the performance of bridges equipped with elastomeric bearings reinforced with fibre under traffic and seismic loads

Aghelfard Arian, Rohanimanesh Mohammad Sadegh, Vatanshenas Ali

Zeszyty Naukowe. Transport / Politechnika Śląska

|

2019

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z. 104

5--14

EN

The seismic elastomeric bearings reinforced with fibre is considered as a new technology in comparison to other conventional isolator systems in civil engineering. In this type of bearing, recycled fibres replaced traditional steel plates used in common bearings. Therefore, this type of bearing has been studied in recent years due to both environmental and cost-saving advantages. The shortage of references about the application of this type of bearing in the bridge industry, and particularly the continuous-span bridges, prompted the researchers in this study to investigate the performance of the isolated reinforced concrete box girder bridges with continuous spans. Reducing the acceleration transmission from the substructure to the superstructure is one of the main advantages of using seismic bearings. Based on the study of the structural models, it was found that, in most cases, elastomeric bearings reinforced with fibres showed a suitable performance and reduced the acceleration applied to the superstructure by absorbing the earthquake energy.

8

Assessment of Emergencies Threatening a Particular Region

Végsöová Oľga, Straka Martin, Šofranko Marian

Rocznik Ochrona Środowiska

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2019

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Tom 21, cz. 1

52--68

EN

The paper focuses on emergencies in a particular region of the Slovak Republic. The focus is mainly on describing the emergencies to which the region is most vulnerable and classifying them, as well as specific locations or businesses where there is a high risk of an emergency occurring. From the point of view of the effects of possible emergencies on the district of Bratislava, the most likely situations are natural disasters (floods from precipitation and watercourses, hailstorms, storms, landslides, ice) and accidents (fires, explosions and releases of dangerous substances). When planning rescue work, it is necessary to start from the worst-case scenario of the emergency, while the most important measure to protect the population is issuing warnings and possible evacuation. Special attention should be paid to the following measures: checking the safety measures around hydrological structures and watercourses, carrying out checks on legal entities and natural persons – entrepreneurs who manufacture, store and handle hazardous substances, preparing controlling organizations, forces and resources to carry out rescue work, preparing the population for self-protection and mutual assistance in the event of emergencies, mutual cooperation of rescue teams in preparation for emergencies, exchange of experience and knowledge with neighbouring districts.

9

Zaawansowane symulacje numeryczne MES dynamiki mostów z wykorzystaniem procedury explicit

Miśkiewicz Mikołaj, Bruski Dawid, Chróścielewski Jacek, Wilde Krzysztof, Grębowski Karol

Mosty

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2019

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nr 1

38--41

PL

Dostęp do mocy obliczeniowej super komputerów oraz możliwość wykorzystania nowoczesnych systemów, np. takich jak Ls-Dyna, pozwala na uzyskanie niezwykle szczegółowych rozwiązań bardzo skomplikowanych problemów inżynierskich.

EN

The article presents some remarks on the dynamic simulations of bridges in the Ls-Dyna system. Some results of two dynamic problems are presented. The first example concerns a viaduct that was hit by a vehicle passing under it. The second one relates to the design of a concrete multi-span bridge subjected to earthquakes of various intensity.

10

Seismically-induced soft-sediment deformation in crevasse-splay microdelta deposits (Middle Miocene, central Poland)

Chomiak Lilianna, Maciaszek Piotr, Wachocki Robert, Widera Marek, Zieliński Tomasz

Geological Quarterly

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2019

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Vol. 63, No. 1

162--177

EN

Crevasse-splay microdelta deposits and their soft-sediment deformation structures (SSDS) are described from a tectonically active lignite-bearing area. These strongly deformed siliciclastic deposits, situated between two lignite benches, are typical of a crevasse-splay microdelta. They accumulated in the overbank zone of a Middle Miocene river system (backswamp area) where shallow ponds or lakes occasionally existed. The deformation takes the form of deformed lamination and load (load casts and flame structures) structures as well as seismic breccias within the first Mid-Polish lignite seam. Ductile deformation structures were generated first by liquefaction and then the breccia was formed under brittle conditions. The brecciation followed a sudden tectonic collapse resulting in an increase in pore pressure related to upward water movement. The occurrence in a tectonic graben and characteristic morphological features suggest an origin of these deformational structures with seismic shocks; thus, they can be called seismites. Hence, we provide strong evidence for accumulation of crevasse-splay sediments in the standing water of a backswamp area, and for tectonic activity in central Poland as the Middle Miocene lignite accumulated.

11

Geologiczne uwarunkowania rozwoju osuwisk w rejonie Krynicy-Zdroju

Rycio E.

Przegląd Geologiczny

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2018

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Vol. 66, nr 5

294--302

EN

The paper presents the final results of mapping work of the Polish Geological Institute - National Research Institute, carried out in the Krynica-Zdrój area in 2010-2012. In the Beskid Niski and Sądecki there are numerous landslides of surface sediments. They also occur in the spa zone of Krynica-Zdrój, posing a threat to its functioning. The basic problem is to recognise the nature of these geohazards and their occurrence in this region. For these reasons, a landslide inventory map was constructed for the whole study area (urban-rural commune). As a result of the analysis, a large variation in the distribution, type and range of landslides has been documented. The landslide surface index and the landslide density index were calculated, concluding that the two indexes differ from each other depending on the geographical position of the analysed area. Both indicators are 2.5-3 times higher for the Krynica-Zdrój town area than for the rural commune area. This variability is associated with different lithologies, tectonics, and geomorphologic features in the area. Krynica-Zdrój lies in the area predisposed to the development of landslides, where the overlapping effects of several passive factors causes mass movements. The Krynica-Zdrój area is composed of thick-bedded sandstones of the Krynica Sandstone Member and the Piwniczna Sandstone Member. They are underlain by variegated shales and thin-bedded turbidites of the Zarzecze Formation. In addition, tectonics of the deep basement is very important. Under the town, there is a deep Krynica fault zone additionally cut by sets of strike-slip faults that altogether cause severe disintegration of the subsurface material and the weakening of cohesive force. The area with the dense sets of faults is an active stress zone. Epicentres of earthquakes probably clustered along all these faults, causing the development and rejuvenation of many landslides in the Krynica-Zdrój area.

12

Hydrogeological Conditions and Natural Factors Forming the Regime of Groundwater Levels in the Ivano-Frankivsk Region (Ukraine)

Davybida L., Kasiyanchuk D., Shtohryn L., Kuzmenko E., Tymkiv M.

Journal of Ecological Engineering

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2018

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Vol. 19, nr 6

34--44

EN

The purpose of the article is to carry out a complex analysis of conditions and natural factors forming the hydrogeological regime as well as to integrate the existing information and groundwater monitoring data in Ivano-Frankivsk region for further creating the unified automated system to collect, process, analyze and store the monitoring observation data. The authors offer methodology, which is based on the geoinformation approach, for organizing and monitoring of the groundwater. The structure of spatial and attributive data that afford to systemize the existing schemes of the hydrogeological zoning as well as the results of long-term observations over variability of the groundwater levels and factors forming the hydrogeological regime were developed. The new approaches for improving the techniques to forecast the groundwater level with due consideration of temporal patterns for changes in water level, the Moon phases and seismic activity, are proposed. The obtained results are considered as an informational basis for reorganization of the state hydrogeological monitoring on the example of Ivano-Frankivsk region.

13

On the association of aerosol optical depth and total ozone fluctuations with recent earthquakes in Greece

Varotsos C. A., Efstathiou M. N., Cracknell A. P.

Acta Geophysica

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2017

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Vol. 65, no. 4

659--665

EN

A number of recent studies suggest that atmospheric changes that precede an earthquake might offer the hope of providing early warning. This study attempts to examine seismo-atmospheric anomalies around the time and the location of some of the major earthquakes in Greece in the period 2001–2015. Daily values of aerosol optical depth (AOD) and total ozone column (TOZ) obtained from satellite observations are used, in the time window between 25 days before and 14 days after each of these events, in a 1° × 1° area centred on the epicentre of each earthquake. For some of these earthquake events, abnormal increases in time series of AOD and TOZ data were detected before and after the occurrence of the earthquake. Nevertheless, in other cases, no clear anomalies were observed around the earthquake date. In addition, examining the statistics of AOD and TOZ daily values, there were many cases of prominent abnormal variations, without, however, being associated with an earthquake event. Therefore, no clear association was found between AOD and TOZ fluctuations and recent earthquakes in Greece.

14

Incorporating space, time, and magnitude measures in a network characterization of earthquake events

Janer C. D., Biton D. C., Batac R. C.

Acta Geophysica

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2017

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Vol. 65, no. 6

1153--1166

EN

We investigate the structural properties of a spatio-temporal network of earthquake events that incorporates magnitude information between the connected events. The network creates temporally directed links from an origin event towards a later event if it breaks the record closest distance from the origin among all the events in the catalog so far. Additionally, the links are conditionally classified based on the magnitude difference between connected events: “up” (“down”) connections point from a weaker (stronger) to a stronger (weaker) event. Using earthquake records from the Philippines from 1973 to 2012 and southern California from 1982 to 2012, we observe that the out-degree distributions show slight deviations from the corresponding Poisson distribution of the same mean. The space and time separations of connected earthquakes both show power-law regimes, suggesting spatio-temporal (self)organization. More importantly, the conditional distributions of “up” and “down” connections in space, time, and network structure point to a higher likelihood of a stronger event triggering a nearby weaker event for the first few connections, as in the case of aftershocks. The results are captured by a sandpile-based model where a small but finite probability of preferentially targeting the most susceptible grid site is introduced. Our analysis, coupled with the discrete model analog, provides a quantitative picture of the spatio-temporal and magnitude organization of seismicity beyond just the successive events. The technique may be extended to further characterize similar long-period earthquake records to yield a more complete picture of the underlying processes involved in seismicity.

15

Statistical Properties of the Immediate Aftershocks of the 15 October 2013 Magnitude 7.1 Earthquake in Bohol, Philippines

Batac R. C.

Acta Geophysica

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2016

|

Vol. 64, no. 1

15--25

EN

The aftershock records of the magnitude 7.1 earthquake that hit the island of Bohol in central Philippines on 15 October 2013 is investigated in the light of previous results for the Philippines using historical earthquakes. Statistics of interevent distances and interevent times between successive aftershocks recorded for the whole month of October 2013 show marked differences from those of historical earthquakes from two Philippine catalogues of varying periods and completeness levels. In particular, the distributions closely follow only the regimes of the historical distributions that were previously attributed to the strong spatio-temporal correlations. The results therefore suggest that these correlated regimes which emerged naturally from the analyses are strongly dominated by the clustering of aftershock events.

16

Scaling Analysis of Time Distribution between Successive Earthquakes in Aftershock Sequences

Marekova E.

Acta Geophysica

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2016

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Vol. 64, no. 4

885--903

EN

The earthquake inter-event time distribution is studied, using catalogs for different recent aftershock sequences. For aftershock sequences following the Modified Omori’s Formula (MOF) it seems clear that the inter-event distribution is a power law. The parameters of this law are defined and they prove to be higher than the calculated value (2 – 1/p). Based on the analysis of the catalogs, it is determined that the probability densities of the inter-event time distribution collapse into a single master curve when the data is rescaled with instantaneous intensity, R(t; Mth), defined by MOF. The curve is approximated by a gamma distribution. The collapse of the data provides a clear view of aftershock-occurrence self-similarity.

17

Hybrid-Empirical Ground Motion Estimations for Georgia

Tsereteli N., Askan A., Hamzehloo H.

Acta Geophysica

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2016

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Vol. 64, no. 5

1225--1256

EN

Ground motion prediction equations are essential for several purposes ranging from seismic design and analysis to probabilistic seismic hazard assessment. In seismically active regions without sufficiently strong ground motion data to build empirical models, hybrid models become vital. Georgia does not have sufficiently strong ground motion data to build empirical models. In this study, we have applied the host-totarget method in two regions in Georgia with different source mechanisms. According to the tectonic regime of the target areas, two different regions are chosen as host regions. One of them is in Turkey with the dominant strike-slip source mechanism, while the other is in Iran with the prevalence of reverse-mechanism events. We performed stochastic finite-fault simulations in both host and target areas and employed the hybrid-empirical method as introduced in Campbell (2003). An initial set of hybrid empirical ground motion estimates is obtained for PGA and SA at selected periods for Georgia.

18

Ciśnienie hydrostatyczne w oceanach przyczyną dryfu płyt tektonicznych i przyczyną trzęsień Ziemi? Hipoteza klinów hydrostatycznych

Wyciszczok S.

Przegląd Geologiczny

|

2015

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Vol. 63, nr 8

449--453

EN

The article presents the likely cause of cracks in the continental and oceanic lithospheric plates, and the probable causes of earthquakes initiating Earth’s speed changes. As the root cause of one of the earthquakes, the author adopts a rotational speed of the globe (reasons: changes of the ocean level, convection currents, or a change in the ice cover) causing the formation of small d’Alambert’s forces with a latitudinal direction, which affect the tectonic plates. The author shows that there is a natural amplifier in the lithosphere, which converts the small d’Alambert’s forces into forces capable of moving tectonic plates on the asthenosphere. The energy to produce the drift of tectonic plates comes from the potential energy of water column in the oceans and some lakes. Thus, the author also explains where the continent-moving forces come from, unlike AlfredWegener who was not able tounravelthis. It should be emphasized that the earthquake in 2011 (Fukushima) occurred during theEarth’s speed change. Current hypotheses should be re-examined and the reason for tectonic plate drift should be re-considered taking into account the hydrostatic pressure – a factor influencing the water column in the oceans and some lakes, and affecting the change in rotation speed of the Earth. The author believes that it is appropriate to carry out work to identify a close relationship between the changes in the Earth’s speed and earthquakes initiated by these changes, which would allow to forecast some earthquakes.

19

Zastosowanie metodologii geodezji naturalnej w predykcji trzęsień ziemi (na przykładzie trzęsienia Virginia 23.08.2011)

Adamczewski Z.

Przegląd Geodezyjny

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2014

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R. 86, nr 1

3--7

PL

Wobec rozwoju metod opracowania coraz liczniejszych zbiorów obserwacji, np. w postaci „chmur punktów”, dystans interpretacyjny otrzymywanych wyników do rzeczywistości zwiększa się czasem tak znacznie, że zastosowany model trudno odróżnić od metafory. W niniejszej pracy powracamy do korzeni tych metod, pokazując, na konkretnym przykładzie – zaskakującego trzęsienia w pobliżu Waszyngtonu w sierpniu 2011 r., zastosowanie najprostszego modelu „naturalnego”, skracającego dystans interpretacyjny.

EN

Considering the development of processing methods of sets of observations of growing numbers of elements, such as "point cloud", it may be stated that the interpretation distance between obtained results and the reality is so increased that it is difficult to distinguish between the applied model and a metaphor. In this paper the authors return to the roots of those methods and present - using the selected example of the surprising earthquake which happened close to Washington in August 2011 - utilisation of the simplest "natural" model, which shortens interpretation distance.

20

Ground fissures in the area of Mavropigi Village (N. Greece): Seismotectonics or mining activity?

Kalogirou E. E., Tsapanos T. M., Karakostas V. G., Marinos V. P., Chatzipetros A.

Acta Geophysica

|

2014

|

Vol. 62, no. 6

1387--1412

EN

In the beginning of July 2010, a ground fissure was observed in the field near the village of Mavropigi (Northern Greece) and specifically in its NW side. Later on (early September), a second ground fissure was perceived, close and almost parallel to the first one and very close to the limits of the lignite exploitation mine (by the Public Power Corporation, PPC). It was observed that the village of Mavropigi slides away slowly towards the PPC lignite mine. Geological, seismological, as well as geotechnical survey in the field indicated that the phenomenon is related to the coal mining exploitation in the near vicinity of the village rather than to any seismotectonic activity in the surrounding area.