An Atypical Shallow Mw 5.3, 2021 Earthquake in the Western Corinth Rift (Greece)

Autor: Jiří Zahradník, El Madani Aissaoui, Pascal Bernard, Pierre Briole, Simon Bufféral, Louis De Barros, Anne Deschamps, Panagiotis Elias, Christos P. Evangelidis, Ioannis Fountoulakis, František Gallovič, Vasilis Kapetanidis, George Kaviris, Olga‐Joan Ktenidou, Sophie Lambotte, Olivier Lengliné, Helene Lyon‐Caen, Mark Noble, Vladimír Plicka, Alexis Rigo, Zafeiria Roumelioti, Anna Serpetsidaki, Efthimios Sokos, Nicholas Voulgaris
Přispěvatelé: Charles University [Prague] (CU), Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), 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-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), National Observatory of Athens (NOA), Institute of Geodynamics [Athens], Faculty of Mathematics and Physics [Praha/Prague], Department of Geology and Geoenvironment, National and Kapodistrian University of Athens (NKUA), Institut Terre Environnement Strasbourg (ITES), École Nationale du Génie de l'Eau et de l'Environnement de Strasbourg (ENGEES)-Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre de Géosciences (GEOSCIENCES), Mines Paris - PSL (École nationale supérieure des mines de Paris), Department of Geology, University of Patras, CRLNET
Rok vydání: 2022
Předmět:
Zdroj: Journal of Geophysical Research : Solid Earth
Journal of Geophysical Research : Solid Earth, 2022, 127 (9), pp.e2022JB024221. ⟨10.1029/2022JB024221⟩
Journal of Geophysical Research: Solid Earth 127(9), nestránkováno. (2022)
ISSN: 2169-9356
2169-9313
DOI: 10.1029/2022jb024221
Popis: International audience; Moderate-to-large earthquakes in rifts may occur on leading boundary faults or inner antithetic faults. Here we show a rare case of the 2020–2021 seismic sequence in the Corinth rift, that culminated in the shallow rupture of the antithetic fault, neither preceded nor followed by the leading fault rupture. The hypocenter of the largest shock (Mw 5.3 of 17 February 2021) was located at ∼8 km depth. However, seismic waveform data, supported by satellite-geodetic and tide gauge measurements, pointed to rupture at shallow depth (∼3 km), where no earthquakes were previously observed. We show that the earthquake most probably ruptured two orthogonal, conjugate fault segments: a weak nucleation phase occurred in the microseismically highly active sub-horizontal detachment layer, followed – a few seconds later – by a larger, shallow moment release on a high-angle, south-dipping normal fault. The latter is the Mornos offshore fault, antithetic to the leading, north-dipping Psathopyrgos fault. Our study presents the first instrumental/observational evidence of a very shallow Mw 5+ event in this rift – and one of the few reported worldwide. The depth limit of the main shallow slip patch coincides with the expected crossing of the Mornos fault with the Psathopyrgos fault, stressing the importance of fault segmentation and rooting inherited from the rift history. This unusual shallow slip in a depth range with little background seismicity and few aftershocks needs to be further investigated by dynamic modeling as a possible prototype of hazardous events in rift environments.
Databáze: OpenAIRE
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