Wyniki wyszukiwania - BazTech

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Fault modelling, seismic sequence evolution and stress transfer scenarios for the July 20, 2017 (MW 6.6) Kos–Gökova Gulf earthquake, SE Aegean

Sboras Sotirios, Lazos Ilias, Mouzakiotis Evaggelos, Karastathis Vassilios, Pavlides Spyros, Chatzipetros Alexandros

Acta Geophysica

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2020

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Vol. 68, no. 5

1245--1261

EN

The July 20, 2017, MW 6.6 Kos–Gökova Gulf earthquake occurred ofshore, near Bodrum of Turkey and Kos of Greece. It was one of the strongest in the broader area during the last many decades causing two deaths, many injuries and extensive damages. We investigated the evolution of the seismic sequence using seismological and geological tools. The aftershock sequence was relocated mainly in order to defne the geometry of the main seismic source, depicting a NNW-dipping fault plane. It also revealed signifcant clustering, associated with other nearby faults, and asymmetric spatio-temporal evolution. Along with morphotectonic analysis on Kos Island, and other published seismological information (e.g. focal mechanisms), we modelled the seismic source of the mainshock, as well as the one of the strongest aftershocks (August 8, MW 5.3). We applied the Coulomb failure criterion in order to investigate the efect of the mainshock on the strongest aftershock, and the rest of the sequence as well. Using the same method, we also investigated the stress changes of both strongest shocks for the prevailing E–W-trending normal faults in this area. Among other conclusions and implications, we deduce that the prevailing tectonic setting of the Gökova Gulf consists of roughly E–W-striking normal faults forming inner horsts and grabens.

2

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

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

Acta Geophysica

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2017

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Vol. 65, no. 4

589--605

EN

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

3

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.

4

The 2014 Kefalonia Doublet (Mw6.1 and Mw6.0), Central Ionian Islands, Greece: Seismotectonic Implications along the Kefalonia Transform Fault Zone

Karakostas V., Papadimitriou E., Mesimeri M., Paradisopoulou P., Gkarlaouni Ch.

Acta Geophysica

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2015

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Vol. 63, no. 1

1--16

EN

The 2014 Kefalonia earthquake sequence started on 26 January with the first main shock (Mw 6.1) and aftershock activity extending over 35 km, much longer than expected from the causative fault segment. The second main shock (Mw 6.0) occurred on 3 February on an adjacent fault segment, where the aftershock distribution was remarkably sparse, evidently encouraged by stress transfer of the first main shock. The aftershocks from the regional catalog were relocated using a 7-layer velocity model and station residuals, and their distribution evidenced two adjacent fault segments striking almost N-S and dipping to the east, in full agreement with the centroid moment tensor solutions, constituting segments of the Kefalonia Transform Fault (KTF). The KTF is bounded to the north by oblique parallel smaller fault segments, linking KTF with its northward continuation, the Lefkada Fault.

5

A detailed analysis of microseismicity in Samos and Kusadasi (Eastern Aegean Sea) areas

Tan O., Papadimitriou E. E., Pabuccu Z., Karakostas V., Yoruk A., Leptokaropoulos K.

Acta Geophysica

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2014

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Vol. 62, no. 6

1283--1309

EN

A detailed investigation of microseismicity and fault plane solutions are used to determine the current tectonic activity of the prominent zone of seismicity near Samos Island and Kusadasi Bay. The activation of fault populations in this complex strike-slip and normal faulting system was investigated by using several thousand accurate earthquake locations obtained by applying a double-difference location method and waveform cross-correlation, appropriate for areas with relatively small seismogenic structures. The fault plane solutions, determined by both moment tensor waveform inversions and P-wave first motion polarities, reveal a clear NS trending extension direction, for strike slip, oblique normal and normal faults. The geometry of each segment is quite simple and indicates planar dislocations gently dipping with an average dip of 40-45°, maintaining a constant dip through the entire seismogenic layer, down to 15 km depth.

6

Seismotectonic of Belarus and the Baltic sea region

Aizberg R., Garetsky R., Aronov A., Karabanow A., Safonov O.

Technika Poszukiwań Geologicznych

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1999

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R. 38, nr 1

28-37

EN

The main features of the seismotectonics of Belarus and the Baltic region are shown on the seismotectonic map which forms the basis of the general subdivision of the territory into seismic areas. Eighteen seismoactive and potentially seismoactive zones of probable occurrence of earthquake foci (PEF) are distinguished. Their sizes are determined taking into consideration the morphology and kinematics of active faults, the prevailing depth of occurrence of earthquake foci and the maximum sizes of foci areas. The greatest possible magnitude of earthquakes is calculated from the data reflecting seismotectonic potential, or real maximum magnitude noted within the given PEF zone. The Pripyat seismoactive superzone (Mmax=3.5-5.0), Minsk (Mmax=3.7), Riga (Mmax=3.5-4.5), West and Central Estonian (Mmax =4.0-4.5), Osmussar (Mmax=4.7), Vilnius (Mmax=4.9) and Oshmiany (Mma)<= 4.5) seismoactive zones are distinguished with the greatest certainty. The Borisov (Mmax=4.0), Kaliningrad-Lithuanian (Mmal<=4.0), Orsha (Mmax=3.5) and Chashniki (Mmax =3.5) areas are identified as potentially seismoactive zones.

PL

Główne elementy sejsmotektoniczne Białorusi i rejony Bałtyku są przedstawione na mapie stanowiącej podstawę podziału obszaru na 18 odrębnych stref, w różnym stopniu aktywnych sejsmicznie, lub tylko potencjalnie aktywnych, w których wyznaczono potencjalne ogniska trzęsień ziemi (Probable Earthquake Foci PEF). Wielkości tych podobszarów określono na podstawie przesłanek morfologicznych oraz kinematyki aktywnych uskoków i maksymalnych wymiarów potencjalnych ognisk trzęsień ziemi. Maksymalną przypuszczalną magnitudę określano na podstawie założeń sejsmotektonicznych przy uwzględnieniu rzeczywistych, rejestrowanych magnitud trzęsień ziemi w danej strefie. Następujące strefy wyznaczono z największym prawdopodobieństwem: Strefa Prypeci (Mmax=3.5-5.0), Mińska (Mmax=3.7), Rygi (Mmax=3.5-4.5), Zachodniej i Centralnej Estonii (Mma)(=4.0-4.5), Osmussaru (Mma]< =4.7), Wilna (Mmax=4.9), Oszmiany (Mmax=4.5). Jako potencjalnie aktywne wyróżniono strefy Borysów (Mmax =3.5-5.0), Kaliningradzko-Litewską (Mmax =4.0), Orszy (Mmax=3.5) i Czasników (Mmax =3.5).