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The 2020 Samos (Aegean Sea) M7 earthquake: a normal fault with rupture directivity and near surface slip explaining the tsunami generation and coastal uplift
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  • Vladimir Plicka,
  • Frantisek Gallovic,
  • Jiří Zahradník,
  • Anna Serpetsidaki,
  • Efthimios Sokos,
  • Nikos Vavlas,
  • Anastasia A. Kiratzi
Vladimir Plicka
Charles University

Corresponding Author:[email protected]

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Frantisek Gallovic
Charles University, Faculty of Mathematics and Physics, Dept. of Geophysics
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Jiří Zahradník
Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic
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Anna Serpetsidaki
University of Patras
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Efthimios Sokos
University of Patras
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Nikos Vavlas
Aristotle University
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Anastasia A. Kiratzi
Aristotle University
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Abstract

The 30 October 2020 M7 Samos earthquake occurred offshore the Greece-Turkey cross border region, and will be recalled as among the deadliest (118 fatalities) that affected both countries. It generated a strong tsunami and caused coseismic uplift of 20 to 35 cm of the NW part of the Samos Island. It ruptured a ~60 km long, north-dipping normal fault, related to the back-arc extension of the Aegean Sea area. Using picks from regional strong motion and broad-band waveforms we relocated the mainshock and the aftershocks, applying suitable velocity models. The closest strong-motion recordings, constrained the finite fault slip model, suggesting up-dip and westward propagation of the rupture. The westward rupture propagation is independently confirmed by the apparent source time functions inferred using the empirical Green’s function method from near-regional broad-band and strong-motion waveforms. Static displacements measured by GNSS stations constrain near surface slip of ~1 m, explaining the tsunami and the island uplift. The 2020 Samos event showed that normal faults bounding the basins in the back-arc Aegean region can host M7 earthquakes and when combined with tsunami generation, constitute a constant threat for the nearby coastal areas of both Greece and Turkey.