Abstract
On 30 October 2020 a MW 7.0 earthquake occurred in the eastern Aegean Sea, between the Greek island of Samos and Turkey’s Aegean coast, causing considerable seismic damage and deaths, especially in the Turkish city of Izmir, approximately 70 km from the epicenter. In this study, we provide a detailed description of the Samos earthquake, starting from the fault rupture to the ground motion characteristics. We first use Interferometric Synthetic Aperture Radar and Global Positioning System data to constrain the source mechanisms. Then, we utilize this information to analyze the ground motion characteristics of the mainshock in terms of peak ground acceleration (PGA), peak ground velocity, and spectral pseudo-accelerations. Modelling of geodetic data shows that the Samos earthquake ruptured a NNE-dip** normal fault located offshore north of Samos, with up to 2.5–3 m of slip and an estimated geodetic moment of 3.3 ⨯ 1019 Nm (MW 7.0). Although low PGA were induced by the earthquake, the ground shaking was strongly amplified in Izmir throughout the alluvial sediments. Structural damage observed in Izmir reveals the potential of seismic risk due to the local site effects. To better understand the earthquake characteristics, we generated and compared stochastic strong ground motions with the observed ground motion parameters as well as the ground motion prediction equations, exploring also the efficacy of the region-specific parameters which may be used to better predict the expected ground shaking from future large earthquakes in the region.
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Acknowledgements
Most of the figures have been created using the Generic Map** Tool version 4.2.1 (www.soest.hawaii.edu/gmt) and the Seismic Analysis Code (SAC) software IRIS SeisCode (washington.edu). We use Copernicus Sentinel-1 InSAR imagery (https://scihub.copernicus.eu/). Sentinel-1 data are copyright of Copernicus (2020). We thank Athanassios Ganas of the National Observatory of Athens for sharing GPS data. The strong motion data used in this study were obtained from the Earthquake Department of the Disaster and Emergency Management Presidency, AFAD, Kandilli Observatory and earthquake Research Institute, KOERI. We thank everyone who contributed to this matter. We thank Gail Atkinson, Dariush Motazedian, and David Boore for providing the computer code to generate ground motion simulations (EXSIM). Some of the amplifications are computed using the programs site_amp and nrattle, available from the online software link at www.daveboore.com. Authors would like to thank Simon J. Ellis for the correction of English style, grammar and spelling. We thank R. B. Herrmann from Saint Louis University for his helpful contribution on the earthquake magnitude and the moment tensor solution.
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Akinci, A., Cheloni, D. & Dindar, A.A. The 30 October 2020, M7.0 Samos Island (Eastern Aegean Sea) Earthquake: effects of source rupture, path and local-site conditions on the observed and simulated ground motions. Bull Earthquake Eng 19, 4745–4771 (2021). https://doi.org/10.1007/s10518-021-01146-5
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DOI: https://doi.org/10.1007/s10518-021-01146-5