Coseismic Surface Deformation, Fault Modeling, and Coulomb Stress Changes of the March 2021 Thessaly, Greece, Earthquake Sequence Based on InSAR and GPS Data

Kontoes, Charalampos; Alatza, Stavroula; Chousianitis, Konstantinos; Svigkas, Nikos; Loupasakis, Constantinos; Atzori, Simone; Apostolakis, Alexis

doi:10.1785/0220210112

Cited by 11 publications

(4 citation statements)

References 55 publications

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“…Utilizing a pair of images just before and after the first mainshock, the uplift and subsidence were estimated, also delineating the surficial location of the seismic fault in the alpine basement of the Zarko Mt. Similar results have been published by other research teams as well [67,[71][72][73][74][75][76][77]. The results of Yang et al [77], based on InSAR analysis and relocated aftershocks, suggest that at least four unmapped low-angle normal faults were activated.…”

Section: Ground Deformation Phenomenasupporting

confidence: 57%

“…This fault setting was also adopted by Kassaras et al [68]. Kontoes et al [75], based on the InSAR results and the proposed nodal planes, modelled all three previous events dipping to the NE, with the fault plane lying a couple of kilometres (1.4-3.1 km) below the surface. Koukouvelas et al [72] insist that there is an apparent mismatch between field and interferometric data implying that the responsible fault for the first mainshock (March 3) is the SSW-dipping "Mesochori" fault (Figure 17), i.e., a fault that bounds the northern flank of the Titarissios River.…”

Section: Discussionmentioning

confidence: 99%

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The Geological Structure and Tectonic Complexity of Northern Thessaly That Hosted the March 2021 Seismic Crisis

Sboras

Pavlides²,

Κίλιας³

et al. 2022

Geotechnics

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Knowing the rich presence of active faults in northern Thessaly and the lack of any significant seismic activity since at least the mid-1940s, the 2021 seismic sequence did not surprise us. What did surprise us was the fact that (i) despite the great knowledge of the neotectonic faults in the area, the causative faults were unknown, or almost unknown; (ii) the direction of the 2021 faulting was different than the expected, and given that the focal mechanisms showed almost pure normal dip-slip motion, the extensional main axis was also different than the one we thought we knew for this area; and (iii) besides the co-seismic ruptures that occurred within the Domeniko-Amouri basin and along the Titarissios River valley, there is evidence of rupturing in the alpine basement of Zarkos mountains. After thoroughly reviewing both the alpine and neotectonic structural setting and all the available literature concerning the seismotectonic data and interpretations of the 2021 sequence, including investigations of our own, we end up in a complex tectonic setting with older alpine structures now operating as inherited faults, and we also suggest the possible occurrence of a roughly N-dipping, low-angle, detachment-type fault. This fault runs below Mt Zarkos, reaching at least the Elassona Basin, with splay faults bifurcating upwards from the main fault zone. Following this complexity, rupture of the first mainshock must have chosen a split route reaching the surface through the gneiss rocks of Zarkos and almost (?) reaching the basinal sediments of the local tectonic depressions. This seismic sequence is a perfect case study to shed some light on the tectonic and rupture processes in the context of both geodynamics and seismic hazard assessment.

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Section: Ground Deformation Phenomenasupporting

confidence: 57%

Section: Discussionmentioning

confidence: 99%

The Geological Structure and Tectonic Complexity of Northern Thessaly That Hosted the March 2021 Seismic Crisis

Sboras

Pavlides²,

Κίλιας³

et al. 2022

Geotechnics

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“…Interestingly, in the vicinity of the broader epicentral area of the 2021 Tyrnavos seismic sequence the extensional axes that we calculated follow a NE‐SW direction which deviates from the general N‐S orientation of extension in Thessaly that has been estimated from geological data (Caputo & Pavlides, 1993). However, this NE‐SW direction is compatible with the NW‐SE strike of the coseismic ground ruptures that were revealed by post‐earthquake field observations and InSAR data (Chatzipetros et al., 2021; Kontoes et al., 2022; Koukouvelas et al., 2021; Mouslopoulou et al., 2022; Sboras et al., 2022) and is in agreement with the NE‐SW extensional stress field obtained from the focal mechanisms of the 2021 Tyrnavos seismic sequence (Kassaras et al., 2022) and with geomorphic indicators which suggest repeated past ruptures on the 2021 causative faults (Mouslopoulou et al., 2022). In this context, it turns out that the orientation of the faults that ruptured during the 2021 sequence was not incompatible with the present‐day crustal strain orientation as it was initially believed (Lazos et al., 2021; Sboras et al., 2022) and it appears that the occurrence of this earthquake sequence is well‐justified by the active strain field.…”

Section: Quantification Of Geodetic Deformation Ratessupporting

confidence: 79%

The Upper Crustal Deformation Field of Greece Inferred From GPS Data and Its Correlation With Earthquake Occurrence

Chousianitis,

Sboras,

Mouslopoulou

et al. 2024

JGR Solid Earth

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We present a new geodetic strain rate and rotation rate model for Greece that has been derived using a highly dense GPS velocity field. The spatial distribution and the resolved rates of the various velocity gradient tensor quantities provided updated constraints on the present‐day upper crustal deformation in the region and revealed new details not reported previously. The spatial distribution of the second invariant demonstrated that the overall magnitude of strain rates is highest across two well‐defined provinces. The first follows the North Anatolian Fault and its two branches within the north Aegean, crosses central Greece and through the Gulf of Corinth it terminates in western Greece, while the second encompasses the extensional province of western Turkey and the eastern Aegean Sea islands. Our estimates revealed that shearing affects some of the fault‐bounded grabens of central Greece that lie to the SW of the North Aegean Basin implying considerable oblique extension. We identified a narrow region of counterclockwise rotation whose location and kinematics have been induced by the net effect across the intersection of the clockwise rotating domains of western and central Greece. The Aegean microplate and the Anatolian plate are separated by a wide transition zone which accommodates the curved stretching of the entire plate system. In both edges of the Hellenic forearc the dominant mode of crustal strain is E‐W extension. We found that earthquakes of M ≥ 5.6 are spatially well‐correlated with high‐strain areas, indicating that strain rate mapping could be used to inform future probabilistic seismic hazard analyses.

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“…DInSAR Analysis: SAR interferometry is a well-established method for mapping co-seismic surface deformation [27][28][29] .…”

Section: Optical Satellite Dataset and Processingmentioning

confidence: 99%

Impact assessment of the catastrophic earthquakes of 6 February 2023 in Turkey and Syria via the exploitation of satellite datasets

Fotiou,

Argyriou,

Alatza

et al. 2023

Ninth International Conference on Remote Sensing and Geoinformation of the Environment (RSCy2023)

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Turkey due to its location within the collision zone between the Eurasian, African and Arabian Plates, is a region prone to earthquakes. The country mostly lies on the Anatolian micro-plate, bounded by two major strike-slip fault zones, i.e., the North and the East Anatolian Fault. On 6 February 2023, the activation of a large segment of the East Anatolian Fault generated two earthquakes of 7.8 and 7.5 magnitude, in southern Turkey. The seismic risk is greater along the plate boundaries, however due to the frequency of earthquake occurrence throughout Turkey, detailed seismic risk maps are crucial and need to be continuously updated towards operational purposes, and as the optimal means towards decision making for disaster risk reduction. Extensive Synthetic Aperture Radar (SAR) satellite image analysis was performed to determine ground displacements caused by the seismic sequence in the wider area around the two epicenters. Pre-seismic line of sight displacements, as well as co-seismic deformation, were estimated, providing critical information about the surface rupture and the overall ground deformation in the affected areas. Earthquakes can induce landslides and other ground displacements causing extensive damage to buildings and infrastructure. Therefore, optical (e.g., Sentinel-2, PlanetScope) and SAR (Sentinel-1) imagery were exploited as a useful tool for assessing the impact of earthquakes on the ground. The monitoring and mapping of these changes, in conjunction with SAR analysis, as well as information on building infrastructure and population density, highlight the overall damage assessment in the region, thus, allowing a better understanding of the impact of earthquakes while providing a more effective response and recovery efforts for decision makers and local authorities towards disaster risk reduction.

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Coseismic Surface Deformation, Fault Modeling, and Coulomb Stress Changes of the March 2021 Thessaly, Greece, Earthquake Sequence Based on InSAR and GPS Data

Cited by 11 publications

References 55 publications

The Geological Structure and Tectonic Complexity of Northern Thessaly That Hosted the March 2021 Seismic Crisis

The Geological Structure and Tectonic Complexity of Northern Thessaly That Hosted the March 2021 Seismic Crisis

The Upper Crustal Deformation Field of Greece Inferred From GPS Data and Its Correlation With Earthquake Occurrence

Impact assessment of the catastrophic earthquakes of 6 February 2023 in Turkey and Syria via the exploitation of satellite datasets

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