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4. Source Mechanism and Rupture Process of the 24 January 2020 Mw 6.7 Doğanyol–Sivrice Earthquake obtained from Seismological Waveform Analysis and Space Geodetic Observations on the East Anatolian Fault Zone (Turkey)

Author

Taymaz, Tuncay, Ganas, Athanassios, Yolsal-Çevikbilen, Seda, Vera, Felipe, Eken, Tuna, Erman, Ceyhun, Keleş, Derya, Kapetanidis, Vasilis, Valkaniotis, Sotirios, Karasante, Ilektra, Tsironi, Varvara, Gaebler, Peter, Melgar, Diego, and Öcalan, Taylan

Published
2021
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6. The 2020 Mw 7.0 Samos (Eastern Aegean Sea) Earthquake: joint source inversion of multitype data, and tsunami modelling.

Author

Sun, Yu-Sheng, Melgar, Diego, Ruiz-Angulo, Angel, Ganas, Athanassios, Taymaz, Tuncay, Crowell, Brendan, Xu, Xiaohua, Tsironi, Varvara, Karasante, Ilektra, Yolsal-Çevikbilen, Seda, Erman, Ceyhun, Irmak, Tahir Serkan, Çubuk-Sabuncu, Yeşim, and Eken, Tuna

Subjects
TSUNAMI warning systems, TSUNAMIS, EARTHQUAKES, GROUND motion, GLOBAL Positioning System, RISK assessment, EARTHQUAKE aftershocks
Abstract

We present a kinematic slip model and a simulation of the ensuing tsunami for the 2020 M w 7.0 Néon Karlovásion (Samos, Eastern Aegean Sea) earthquake, generated from a joint inversion of high-rate GNSS, strong ground motion and InSAR data. From the inversion, we find that the source time function has a total duration of ∼20 s with three peaks at ∼4, 7.5 and 15 s corresponding to the development of three asperities. Most of the slip occurs at the west of the hypocentre and ends at the northwest downdip edge. The peak slip is ∼3.3 m, and the inverted rake angles indicate predominantly normal faulting motion. Compared with previous studies, these slip patterns have essentially similar asperity location, rupture dimension and anticorrelation with aftershocks. Consistent with our study, most published papers show the source duration of ∼20 s with three episodes of increased moment releases. For the ensuing tsunami, the eight available gauge records indicate that the tsunami waves last ∼18–30 hr depending on location, and the response period of tsunami is ∼10–35 min. The initial waves in the observed records and synthetic simulations show good agreement, which indirectly validates the performance of the inverted slip model. However, the synthetic waveforms struggle to generate long-duration tsunami behaviour in simulations. Our tests suggest that the resolution of the bathymetry may be a potential factor affecting the simulated tsunami duration and amplitude. It should be noted that the maximum wave height in the records may occur after the decay of synthetic wave amplitudes. This implies that the inability to model long-duration tsunamis could result in underestimation in future tsunami hazard assessments. [ABSTRACT FROM AUTHOR]

Published
2024
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7. The 2 December 2020 MW 4.6, Kallithea (Viotia), central Greece earthquake: a very shallow damaging rupture detected by InSAR and its role in strain accommodation by neotectonic normal faults.

Author

Valkaniotis, Sotiris, De Novellis, Vincenzo, Ganas, Athanassios, Sansosti, Eugenio, Convertito, Vincenzo, Briole, Pierre, Tsironi, Varvara, Karasante, Ilektra, and Karamitros, Ioannis

Subjects
ROLE conflict, EARTHQUAKES, NATURAL disaster warning systems, NEOTECTONICS, DEFORMATION of surfaces, GLOBAL Positioning System
Abstract

On 2 December 2020 10:54 UTC a shallow earthquake of MW (NOA) = 4.6 occurred near the village of Kallithea (to the east of Thiva), central Greece, which, despite its modest size, was locally damaging. Using InSAR and GNSS data, we mapped a permanent change on the ground surface, i.e., a subsidence of 7 cm. Our geodetic inversion modelling indicates that the rupture occurred on a WNW–ESE striking, SSW-dipping normal fault, with a dip-angle of ~ 54°. The maximum slip value was 0.35 m, which was reached at a depth of about 1100 m. The analysis of broadband seismological data also provided kinematic source parameters such as moment magnitude MW = 4.6 (± 0.1), rupture area 6.3 km2 and mean slip 0.16 m, which agree with the values obtained from the geodetic model. The effects of the earthquake were disproportionate to its moderate magnitude, probably due to its unusually shallow depth (slip centroid at 1.1 km) and the high efficiency of the earthquake (radiation efficiency η = 0.62). The geodetic data inversion also indicates that within the uncertainty limits of the technique, three scenarios are possible (a) the earthquake responsible for the mapped surface deformation may have occurred on a ~ 2-km long, blind normal fault different from the well-known active Kallithea normal fault or (b) could have occurred along a secondary fault that branches off the Kallithea fault or (c) it may have occurred along the Kallithea fault itself, but with its geometrical configuration could not be modelled with available data. We have also concluded that with a high dip-angle Kallithea Fault forward model it is not possible to fit the geodetic data. The rupture initiated at a very shallow depth (1.1 km) and it could not propagate deeper possibly because of a structural barrier down-dip. The 2020 event near Kallithea highlighted the structural complexity in this region of the Asopos Rift valley as the reactivation of the WNW–ESE structures indicates their significant role in strain accommodation and that they still represent a seismic hazard for this region. [ABSTRACT FROM AUTHOR]

Published
2024
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8. Sub- and super-shear ruptures during the 2023 Mw 7.8 and Mw 7.6 earthquake doublet in SE Türkiye

Author

Melgar, Diego, primary, Taymaz, Tuncay, additional, Ganas, Athanassios, additional, Crowell, Brendan, additional, Öcalan, Taylan, additional, Kahraman, Metin, additional, Tsironi, Varvara, additional, Yolsal-Çevikbil, Seda, additional, Valkaniotis, Sotiris, additional, Irmak, Tahir Serkan, additional, Eken, Tuna, additional, Erman, Ceyhun, additional, Özkan, Berkan, additional, Dogan, Ali Hasan, additional, and Altuntaş, Cemali, additional

Published
2023
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10. The Arkalochori Mw = 5.9 Earthquake of 27 September 2021 Inside the Heraklion Basin: A Shallow, Blind Rupture Event Highlighting the Orthogonal Extension of Central Crete

Author

Ganas, Athanassios, primary, Hamiel, Yariv, additional, Serpetsidaki, Anna, additional, Briole, Pierre, additional, Valkaniotis, Sotiris, additional, Fassoulas, Charalampos, additional, Piatibratova, Oksana, additional, Kranis, Haralambos, additional, Tsironi, Varvara, additional, Karamitros, Ioannis, additional, Elias, Panagiotis, additional, and Vassilakis, Emmanuel, additional

Published
2022
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15. Domino-style earthquakes along blind normal faults in Northern Thessaly (Greece): kinematic evidence from field observations, seismology, SAR interferometry and GNSS

Author

Ganas, Athanassios, primary, Valkaniotis, Sotiris, additional, Briole, Pierre, additional, Serpetsidaki, Anna, additional, Kapetanidis, Vassilis, additional, Karasante, Ilektra, additional, Kassaras, Ioannis, additional, Papathanassiou, George, additional, Karamitros, Ioannis, additional, Tsironi, Varvara, additional, Elias, Panagiotis, additional, Sarhosis, Vasilis, additional, Karakonstantis, Andreas, additional, Konstantakopoulou, Emmanouela, additional, Papadimitriou, Panagiotis, additional, and Sokos, Efthimios, additional

Published
2021
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16. The March 2021 seismic sequence in Larisa - Damasi , Thessaly (central Greece), its seismotectonic characteristics and geodynamic effects

Author

Ganas, Athanassios, Valkaniotis, Sotiris, Tsironi, Varvara, Karasante, Ilektra, Elias, Panagiotis, Kapetanidis, Vassilis, Kasssaras, Ioannis, Papathanassiou, George, Briole, Pierre, Laboratoire de géologie de l'ENS (LGENS), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
InSAR, inversion, Earthquake, seismotectonic characteristics and geodynamic effects, Greece, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], 13. Climate action, liquefaction, deformation, Thessaly, surface breaks, seismic sequence in Damasi, Thessaly (central Greece)
Abstract

On March 3, 2021 a Mw=6.3 shallow earthquake occurred in the mountainous region of Damasi, about 20 km to the northwest of Larisa, Thessaly, central Greece, in a region of active crustal extension but of low strain. This event was followed by a Mw=6.0 shallow earthquake on March 4, 2021 about 12 km to the northwest, inside the sedimentary basin of the Titarisios river. On March 12, 2021 a third event of Mw=5.6 occurred 7 km further towards NNW, near the NW edge of the basin. All events show normal-slip kinematics as indicated by the moment tensor solutions, with minor strike-slip components. Because of the shallow depth of the events it was possible to map the surface deformation using InSAR. The preliminary results from InSAR show three main lobes of subsidence, partially overlapping. The deformation pattern indicates the activation of three normal faults, previously unknown in this part of Thessaly. The earthquakes generated numerous secondary phenomena with vast areas of alluvial deposits exhibiting spectacular liquefaction features. No tectonic ruptures were found in the cases of events 2 and 3, however a series of sporadic, NW-SE striking surface breaks were found on the mountains north of village Zarko that are aligned with the vanishing gradient of the interferometric phase of the 1st event. &nbsp

Published
2021
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17. The early March 2021 Thessaly (Greece) earthquake sequence

Author

Efthymis Lekkas, Agorastos Konstantinos, Mavroulis, Spyridon, Haralambos Kranis, Skourtsos, Emmanuel, Panayotis Carydis, Marilia Gogou, Katerina-Navsika Katsetsiadou, Papadopoulos, Gerassimos A., Triantafyllou, Ioanna, Agalos, Apostolos, Sotiris Moraitis, Stamati, Eleftheria, Psarris, Dimitrios, Kaviris, George, Kapetanidis, Vasilis, Papadimitriou Panayotis, Karakonstantis, Andreas, Spingos, Ioannis, Kouskouna, Vicki, Kassaras, Ioannis, Pavlou, Kyriaki, Voulgaris, Nicholas, Mavrouli, Maria, Pavlides, Spyros, Chatzipetros, Alexandros, Sboras, Sotirios, E. Kremastas, A. Chatziioannou, Kiratzi, Anastasia A., Papazachos, Costas, N. Chatzis, Karakostas, Vasilis, Papadimitriou, Eleftheria, Koukouvelas, Ioannis, Nikolakopoulos, Konstantinos, Aggeliki Kyriou, Apostolopoulos, Dionysios, Zygouri, Vasiliki, Verroios, Sotirios, Belesis, Alexandros, Tsentzos, Ioannis, Krassakis, Pavlos, K. Lymperopoulos, Karavias, Andreas, Bafi, Despoina, Gatsios, Theodoros, M. Karatzia, I. Gkougkoustamos, Falaras, Triantafyllos, Is. Parcharidis, Papathanassiou, George, Evangelidis, Christos, V. Karastathis, Akis Tselentis, Ganas, Athanassios, Tsironi, Varvara, Karasante, Ilektra, Valkaniotis, Sotirios, Galanakis, Dimitrios, Konstantopoulou, Garyfalia, Papadopoulos, Nikitas, Kourou, Asimina, Manousaki, Maria, and Thoma, Thekla

Published
2021
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20. The October 30, 2020, Mw 6.9 Samos (Greece) earthquake

Author

Efthymis Lekkas, Mavroulis, Spyridon, Marilia Gogou, Papadopoulos, Gerassimos A., Triantafyllou, Ioanna, Katerina-Navsika Katsetsiadou, Haralambos Kranis, Skourtsos, Emmanuel, Panayotis Carydis, Voulgaris, Nicholas, Panayotis Papadimitriou, Kapetanidis, Vasilis, Karakonstantis, Andreas, Spingos, Ioannis, Kouskouna, Vicki, Kassaras, Ioannis, Kaviris, George, Pavlou Kyriaki, Vassilis Sakkas, Karatzetzou, Anna, Evelpidou, Niki, Karkani, Eleana, Kampolis, Isidoros, Nomikou, Paraskevi, Danae Labridou, Krassakis, Pavlos, Bafi, Despoina, Gatsios, Theodoros, Markogiannaki, Olga, Is. Parcharidis, Ganas, Athanassios, Tsironi, Varvara, Karasante, Ilektra, Galanakis, Dimitrios, Kontodimos, Konstantinos, Sakellariou, Dimitrios, THEODOULIDIS, Nikos, Karakostas, Christos, Lekidis, Vasileios, Kontantia Makra, Margaris, Vasileios, Kontantinos Morfidis, Papaioannou, Christos, Rovithis, Emmanuel, Salonikios, Thomas N., Kourou, Asimina, Manousaki, Maria, Thoma, Thekla, and Karveleas, Nikos

Published
2020
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21. The Mw = 5.6 Kanallaki Earthquake of 21 March 2020 in West Epirus, Greece: Reverse Fault Model from InSAR Data and Seismotectonic Implications for Apulia-Eurasia Collision

Author

Valkaniotis, Sotiris, primary, Briole, Pierre, additional, Ganas, Athanassios, additional, Elias, Panagiotis, additional, Kapetanidis, Vassilis, additional, Tsironi, Varvara, additional, Fokaefs, Anna, additional, Partheniou, Helena, additional, and Paschos, Panagiotis, additional

Published
2020
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22. The MW = 5.6 Kanallaki Earthquake of March 21, 2020 in West Epirus, Greece: Reverse Fault Model From Insar Data and Seismotectonic Implications for Apulia-Eurasia Collision

Author

Valkaniotis, Sotiris, primary, Briole, Pierre, additional, Ganas, Athanassios, additional, Elias, Panagiotis, additional, Kapetanidis, Vasilis, additional, Tsironi, Varvara, additional, Fokaefs, Anna, additional, Partheniou, Helena, additional, and Paschos, Panagiotis, additional

Published
2020
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24. The 25 October 2018 Mw = 6.7 Zakynthos earthquake (Ionian Sea, Greece): A low-angle fault model based on GNSS data, relocated seismicity, small tsunami and implications for the seismic hazard in the west Hellenic Arc

Author

Ganas, Athanassios, primary, Briole, Pierre, additional, Bozionelos, George, additional, Barberopoulou, Aggeliki, additional, Elias, Panagiotis, additional, Tsironi, Varvara, additional, Valkaniotis, Sotiris, additional, Moshou, Alexandra, additional, and Mintourakis, Ioannis, additional

Published
2020
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26. Design and implementation of the seismotectonic Atlas of Greece v1.0

Author

Kassaras, Ioannis, primary, Kapetanidis, Vasilis, additional, Ganas, Athanassios, additional, Tzanis, Andreas, additional, Papadimitriou, Panayotis, additional, Kouskouna, Vicki, additional, Karakonstantis, Andreas, additional, Valkaniotis, Sotirios, additional, Chailas, Stylianos, additional, Sakkas, Vasileios, additional, Kosma, Chrysanthi, additional, Bozionelos, George, additional, Tsironi, Varvara, additional, and Giannaraki, Georgia, additional

Published
2020
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28. A Preliminary Report On The M7.5 Palu 2018 Earthquake Co-Seismic Ruptures And Landslides Using Image Correlation Techniques On Optical Satellite Data

Author

Valkaniotis Sotiris, Ganas Athanassios, Tsironi Varvara, and Barberopoulou Aggeliki

Subjects
Earthquake, Indonesia, Fault Rupture, Displacement, Sentinel-2
Abstract

We use optical satellite data to map the co-seismic displacements for the Mw=7.5 strike-slip earthquake of 28 September 2018 in Palu, Sulawesi, Indonesia. This was a strike-slip faulting event at shallow depth that occurred within the interior of the Molucca Sea microplate, which is part of the Sunda tectonic plate. Using optical image correlation from Sentinel-2 and Planet imagery, we mapped the surface rupture extent of the earthquake and calculated the co-seismic offsets. Before- and after- the earthquake image acquisitions were analyzed using MicMac software and the MPIC-OPT service on the ESA Geohazards TEP platform. Our results include the mapping of a) the detailed trace of the ruptured fault at the southern part of the region (Palu segment) and b) a more complex deformation pattern at the northern part of the rupture. Analysis of the horizontal displacement field and sequential profiles across the fault also enabled mapping of the fault zone complexity, secondary faulting, fault zone width and large co-seismic gravitational phenomena. A mean displacement of 3-5 metres was calculated for a total earthquake rupture length of more than 140 km. Our results agree with the focal mechanism solution for the earthquake which indicates that the rupture occurred on a left-lateral, north-south striking fault. The significance of this event is also associated with the severity of the tsunami impact attributed to a strike slip fault. Further investigation is necessary to determine the source of the tsunami as primarily tectonic or due to another mechanism although a more complex mechanism is likely., Report submitted to EMSC on 19 October 2018 12:00 UTC

Published
2018
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31. Rupture kinematics of 2020 January 24 Mw 6.7 Doğanyol-Sivrice, Turkey earthquake on the East Anatolian Fault Zone imaged by space geodesy.

Author

Melgar, Diego, Ganas, Athanassios, Taymaz, Tuncay, Valkaniotis, Sotiris, Crowell, Brendan W, Kapetanidis, Vasilis, Tsironi, Varvara, Yolsal-Çevikbilen, Seda, and Öcalan, Taylan

Subjects
FAULT zones, GLOBAL Positioning System, EARTHQUAKE aftershocks, SURFACE fault ruptures, GEODESY, EARTHQUAKES, KINEMATICS
Abstract

Here, we present the results of a kinematic slip model of the 2020 M w 6.7 Doğanyol-Sivrice, Turkey Earthquake, the most important event in the last 50 yr on the East Anatolian Fault Zone. Our slip model is constrained by two Sentinel-1 interferograms and by 5 three-component high-rate GNSS (Global Navigation Satellite System) recordings close to the earthquake source. We find that most of the slip occurs predominantly in three regions, two of them at between 2 and 10 km depth and a deeper slip region extending down to 20 km depth. We also relocate the first two weeks of aftershocks and find a distribution of events that agrees with these slip features. The HR-GNSS recordings suggest a predominantly unilateral rupture with the effects of a directivity pulse clearly seen in the waveforms and in the measure peak ground velocities. The slip model supports rupture propagation from northeast to southwest at a relatively slow speed of 2.2 km s−1 and a total source duration of ∼20 s. In the absence of near-source seismic stations, space geodetic data provide the best constraint on the spatial distribution of slip and on its time evolution. [ABSTRACT FROM AUTHOR]

Published
2020
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33. The Mw 6.6, July 21, 2017 Kos Earthquake. Scientific Report (Version 2.0)

Author

Efthymis Lekkas, Panayotis Carydis, Mavroulis, Spyridon, Marilia Gogou, Andreadakis Emmanuel, Katerina-Navsika Katsetsiadou, Skourtsos, Emmanuel, Minos-Minopoulos, Despina, Bardouli, Pavlina, Voulgaris, Nicholas, Panayotis Papadimitriou, Kaviris, George, Akis Tselentis, Karakonstantis, Andreas, Is. Parcharidis, Papastergios, Asterios, Tsironi, Varvara, Lalechos, Spyridon, Avramea, Vassiliki, Kleanthi, Maria, Papaioannou, Christos, Salonikios, Thomas N., Adam, Nikolaos, and Sakellariou, Dimitris

Published
2017
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34. Ground deformation and microseismicity patterns onshore Milos, Cyclades, Greece.

Author

Ganas, Athanassios, Karakonstantis, Andreas, Kapetanidis, Vasilis, Tsironi, Varvara, Karamitros, Ioannis, Efstathiou, Eirini, Karasante, Ilektra, and Kassaras, Ioannis

Subjects
REMOTE sensing, SEISMOLOGY, ROCK deformation, FAULT zones
Abstract

In this paper, we present the findings of a joint remote-sensing and seismological investigation of Milos (western Cyclades islands, Greece) using geodetic data (InSAR and GNSS) and the recordings of a local seismic network established by NOA in 2021. Our objective was to investigate the ground deformation and seismicity patterns and detect activity along fault zones of the island. We present evidence for on-going activity along a NW-SE, east-dipping fault crossing Milos. [ABSTRACT FROM AUTHOR]

Published
2022

36. The March 2021 seismic sequence in Larisa - Damasi , Thessaly (central Greece), its seismotectonic characteristics and geodynamic effects

Author

Ganas, Athanassios, Valkaniotis, Sotiris, Tsironi, Varvara, Karasante, Ilektra, Elias, Panagiotis, Kapetanidis, Vassilis, Kasssaras, Ioannis, Papathanassiou, George, and Briole, Pierre

Subjects
InSAR, inversion, Earthquake, Greece, 13. Climate action, liquefaction, deformation, Thessaly, surface breaks
Abstract

On March 3, 2021 a Mw=6.3 shallow earthquake occurred in the mountainous region of Damasi, about 20 km to the northwest of Larisa, Thessaly, central Greece, in a region of active crustal extension but of low strain. This event was followed by a Mw=6.0 shallow earthquake on March 4, 2021 about 12 km to the northwest, inside the sedimentary basin of the Titarisios river. On March 12, 2021 a third event of Mw=5.6 occurred 7 km further towards NNW, near the NW edge of the basin. All events show normal-slip kinematics as indicated by the moment tensor solutions, with minor strike-slip components. Because of the shallow depth of the events it was possible to map the surface deformation using InSAR. The preliminary results from InSAR show three main lobes of subsidence, partially overlapping. The deformation pattern indicates the activation of three normal faults, previously unknown in this part of Thessaly. The earthquakes generated numerous secondary phenomena with vast areas of alluvial deposits exhibiting spectacular liquefaction features. No tectonic ruptures were found in the cases of events 2 and 3, however a series of sporadic, NW-SE striking surface breaks were found on the mountains north of village Zarko that are aligned with the vanishing gradient of the interferometric phase of the 1st event., Partially funded by the joint research - industry project MIS-5070928, financed by the EU and the Greek Government

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